Fixing device for brain-spinal cord sample of mouse
By designing a brain-spinal cord fixation device based on anatomical features, the problems of consistency and entanglement in the fixation process of mouse brain and spinal cord were solved, and efficient and reliable three-dimensional reconstruction of neural circuits was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SANYA RES INST OF HAINAN UNIV
- Filing Date
- 2025-12-22
- Publication Date
- 2026-05-01
AI Technical Summary
In existing technologies, it is difficult to maintain the consistency of the three-dimensional positional relationship between the mouse brain and spinal cord when fixing them, which makes the spinal cord prone to entanglement and rotation, affecting the accurate tracking of neural circuits and the reproducibility of experimental results.
A brain-spinal cord fixation device for mice was designed, including a brain fixation groove and a spinal cord fixation groove. Based on anatomical features, a biomimetic design was adopted, combined with a snap-fit fixation system to ensure the natural connection and stable fixation of the brain and spinal cord.
This method achieves standardized fixation of the brain and spinal cord, avoiding spinal cord entanglement and rotation, ensuring the continuity of neural circuits and the reproducibility of experimental results, and improving operational efficiency and slice imaging quality.
Smart Images
Figure CN121954604A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of experimental apparatus technology, and more particularly to a fixation device for a rat brain-spinal cord sample. Background Technology
[0002] In biomedical research, the complete reconstruction of long-range circuits between the brain and spinal cord is crucial, such as pain, itch, and motor circuits. One of the key steps to achieve this goal is to fix the brain and spinal cord tissue of mice as a whole. Due to the slender, soft, and deformable nature of spinal cord tissue, the traditional fixation process faces the following challenges due to the lack of specialized molds: (1) Cumbersome and difficult operation: It is difficult to stably fix long segments of spinal cord in specific anatomical orientations, such as maintaining the sagittal or coronal plane, and to maintain a natural connection with the brain tissue. (2) Poor morphological preservation: The slender spinal cord is prone to entanglement and twisting, which causes changes in the rotation angle of its internal axons, resulting in confusion in the anatomical correspondence between the anterior and posterior segments of the spinal cord and hindering the accurate tracking of neural circuits. (3) Low degree of standardization: It relies on manual placement by operators, making it difficult to ensure the consistency of morphology between different samples and the controllability of the embedding length, resulting in poor reproducibility of experimental results. Therefore, traditional embedding methods generally suffer from problems such as poor consistency between samples, difficulty in controlling the embedding length, and difficulty in tracking and reconstruction due to spinal cord entanglement and rotation.
[0003] Currently, the technical strategy for holistic research on the brain and spinal cord is as follows: the isolated brain tissue and the segmented spinal cord tissue are fixed separately; the fixed tissue blocks are sliced and imaged separately; and finally, relying on the operator's experience, they are manually spliced in software to attempt to reconstruct the complete neural circuit. However, the above approach leads to: (1) splicing misalignment: the anatomical connections between the brain and spinal cord, and between different segments of the spinal cord, are prone to misalignment during the truncation and image splicing process. (2) structural distortion: manual processing cannot avoid the entanglement and rotation of the slender spinal cord, resulting in axonal path distortion and damage to the realism of the three-dimensional reconstruction. (3) large error: the results of different operators or different batches of operations vary significantly, and the embedding length and sample orientation cannot be precisely controlled.
[0004] In summary, there is an urgent need for a specialized fixation device that can standardize and fix the three-dimensional positional relationship between the brain and spinal cord in the initial stage of tissue processing, effectively maintain the natural morphology and orientation of the spinal cord, prevent spinal cord rotation and torsion, and ensure high consistency between samples, so as to achieve three-dimensional continuous reconstruction of long-range brain-spinal cord circuits. Summary of the Invention
[0005] This disclosure provides a fixation device for a rat brain-spinal cord sample to at least solve the above-mentioned technical problems existing in the prior art.
[0006] According to a first aspect of this disclosure, a fixation device for a mouse brain-spinal cord sample is provided, comprising a base, a brain fixation groove and a spinal cord fixation groove disposed on the base, wherein the brain fixation groove and the spinal cord fixation groove are in communication. The brain fixation groove is a biomimetic groove adapted to the anatomical contour of the lateral hemisphere of the mouse brain, used to accommodate the lateral hemisphere of the mouse brain and expose the brainstem end of the mouse brain. The spinal cord fixation groove is a spiral-shaped biomimetic groove adapted to the lateral anatomical contour of the mouse spinal cord, used to accommodate the side of the mouse spinal cord and maintain a natural connection angle between the mouse spinal cord and the end of the brainstem.
[0007] Specifically, the brain fixation groove and the spinal cord fixation groove respectively accommodate the sides of the brain and the spinal cord. This is a key design based on three core objectives: anatomy, neural circuit tracking requirements, and tissue processing efficiency. (1) The physiological connection between the rat brain and spinal cord is as follows: the spinal cord forms a longitudinal connection structure with the brain through the end of the brainstem (medulla oblongata). The connection axis of the two is linearly continuous, rather than perpendicular or intersecting. If the frontal (dorsoventral) placement is adopted, the connection end is easily offset due to the difference in the center of gravity between the brain and the spinal cord (the brain is large and the spinal cord is thin and long). However, the lateral placement can make the lateral contour of the brain (such as the side of the cerebral hemisphere and the side of the brainstem) and the side of the spinal cord (the lateral anatomical structure of the gray / white matter of the spinal cord) completely fit the biomimetic contour of the groove, ensuring that the longitudinal axis of the end of the brainstem and the beginning of the spinal cord are aligned without any front-back or left-right offset, avoiding the misalignment of the connection end commonly seen in traditional manual splicing. It can also ensure that the nerve fibers in the brain-spinal cord connection area maintain their natural direction and are not artificially bent due to incorrect placement, providing a real anatomical basis for subsequent three-dimensional reconstruction. (2) From an anatomical perspective, the lateral aspect of the spinal cord is its non-functionally sensitive area: the dorsal (close to the spine) and ventral (close to the internal organs) sides of the spinal cord contain a large number of nerve fiber bundles. If the dorsal and ventral surfaces are used as the placement surfaces, the uneven force within the surface during spiral coiling can easily cause the dorsal and ventral fibers to be squeezed and deformed. However, the anatomical structure of the lateral (left and right sides) is relatively symmetrical and can withstand slight pressure. When spiral coiling, it is only necessary to follow the curvature of the lateral surface to fit the groove, without compressing the core nerve fibers. From a physical fixation perspective, the spinal cord placed on the side can be evenly pressured along the side using clips: the clip pressure head can accurately act on the side of the spinal cord, stably restricting it within the spiral groove, preventing the spinal cord from rolling in the reagent (if placed on the dorsal and ventral surfaces, the clips are prone to causing the spinal cord to rotate due to the height difference between the dorsal and ventral sides), thus completely solving the problem of spinal cord entanglement and rotation in traditional fixation. (3) The lateral sulcus of the cerebral hemisphere and the facial nerve nucleus region on the side of the brainstem can be clearly observed from the side of the mouse brain. These markings can help operators quickly insert the brain into the groove in the correct direction with the frontal lobe facing forward and the occipital lobe facing backward, without relying on complex instruments for positioning. The lateral boundary line of the spinal cord segments can be observed from the side of the spinal cord. Operators can use these markings to confirm that the segment order is correct when the spinal cord is coiled, and avoid the spinal cord segments being reversed, which would lead to the wrong direction of the neural circuit during subsequent tracking. (4) The mouse brain is ellipsoidal. The projection area on the front (dorsoventral) side is small, while the projection area on the side side is larger. This allows reagents such as fixative and dehydrating solutions to quickly penetrate into the brain from the side through the base. The spinal cord is cylindrical. The side side is its largest circumference surface. When the reagent penetrates from the side, it can act on both the gray and white matter of the spinal cord at the same time. This avoids the problem that when the dorsoventral side is placed, the reagent can only penetrate from the dorsoventral surface and the central gray matter cannot penetrate sufficiently. This ensures that the fixation, dehydration, and transparency of the brain and spinal cord tissues are uniform, and improves the quality of subsequent sections and imaging.
[0008] Specifically, the aforementioned mice can be various types of rodents, such as mice, rats, and hamsters. The structure and morphology of the brain and spinal cord are basically similar among different types of rodents, differing only in size. Larger rodents tend to have slightly larger brains and spinal cords. Therefore, for different types of rodents, only the size of the device needs to be adjusted, while maintaining the shape of the brain fixation groove and spinal cord fixation groove.
[0009] In one embodiment, the brain fixation groove has a length of 15-25 mm, a width of 8-15 mm, and a depth of 5-8 mm.
[0010] Specifically, the size of the brain fixation groove is designed based on the size of the lateral hemisphere of the rat brain.
[0011] Specifically, the width of the brain fixation groove refers to its maximum diameter.
[0012] In one embodiment, the total length of the spinal cord fixation groove is 60-100 mm, the width is 1-2 mm, and the depth is 1-2 mm.
[0013] Specifically, the total length of the spinal cord fixation groove refers to the total length of the spiral groove.
[0014] Specifically, by setting the brain fixation groove and spinal cord fixation groove to the above dimensions, the fixation device can be adapted to various types of rodents. The above dimensions are designed based on the anatomical characteristics of the brain and spinal cord of different rodents. Appropriate fixation devices can be selected and prepared according to the needs (i.e., rodent species) to fix the corresponding rodent brain-spinal cord samples.
[0015] In one embodiment, a transition arc is provided at the connection between the brain fixation groove and the spinal cord fixation groove. The radius of the transition arc is 2-3 mm, which is used to smoothly connect the end of the brainstem of the mouse brain with the beginning of the mouse spinal cord, so as to avoid the bending of nerve fibers at the connection site.
[0016] In one embodiment, the base, the brain fixation groove, and the spinal cord fixation groove are integrally molded, and the integral molding method includes any one of precision injection molding and CNC milling.
[0017] Specifically, if precision injection molding is chosen, the shape of the brain fixation groove and spinal cord fixation groove is designed as a mold cavity, and the grooved base is directly injection molded, with no splicing gap between the groove and the base body. If CNC milling is chosen, the overall base is first machined, and then grooves matching the anatomical contours of the brain and spinal cord are milled on the surface of the base using a precision milling cutter.
[0018] Specifically, the integrated molding process is used because: (1) the brain fixation slot and the spinal cord fixation slot are directly molded on the base, and their relative positions are guaranteed by the processing precision, avoiding the brain-spinal cord misalignment caused by assembly errors in traditional split-joint slots. (2) The seamless integrated structure can prevent the fixation slot from falling off or shifting during sample processing, and at the same time prevent reagent residues in the joints from causing sample contamination, meeting the standardization and cleanliness requirements of experimental operations. (3) No additional installation / calibration of the fixation slot is required. Experimenters can directly place brain and spinal cord samples into the preset grooves, reducing operational errors that rely on experience in traditional manual placement and improving the degree of standardization.
[0019] In one embodiment, the material of the base is selected from at least one of polycarbonate and polytetrafluoroethylene.
[0020] In one embodiment, the base is a mesh structure with square or regular hexagonal mesh holes.
[0021] In one embodiment, the fixation device further includes a snap-fit fixation system, which is arranged along the trajectory of the spinal cord fixation groove to restrict the mouse spinal cord within the spinal cord fixation groove; the snap-fit fixation system includes a plurality of snaps, with a spacing of 5-10 mm between adjacent snaps.
[0022] Specifically, the snap-fit fixation system is designed to stably confine the mouse spinal cord sample within the fixation groove using restraint pressure, preventing it from floating, entangled, rotating, or structurally damaged during fixation, dehydration, and other processes. It also adapts to the anatomical morphology of the mouse spinal cord sample. The number of snaps is determined based on the specific spinal cord sample; longer samples require more snaps, while shorter samples require fewer, offering flexibility.
[0023] In one embodiment, the snap-fit system is arranged along the radial trajectory of the spinal cord fixation groove.
[0024] Specifically, the radial trajectory of the spinal cord fixation groove refers to the direction of rays extending outward from the center of the spiral. Each spiral groove has its corresponding radial ray, and these rays together constitute the radial trajectory system of the spiral groove. For the spinal cord fixation groove (spiral groove) in this disclosure, the movement tendency of the rat spinal cord is to slide around along the spiral axis and move laterally along the spiral radial direction. Therefore, the snap-fit fixation system is set along the radial trajectory (restraining lateral movement), which, together with the spiral shape of the groove itself (restraining around the sliding), perfectly forms a complete constraint on the spiral trajectory.
[0025] In one embodiment, the buckle includes a positioning support unit, an elastic constraint unit, and an adapter connection unit; the positioning support unit is connected to the base and is used to fix the buckle on the base; the elastic constraint unit is used to provide elastic pressure to confine the rat spinal cord within the spinal cord fixation groove; the adapter connection unit is used to connect the positioning support unit and the elastic constraint unit.
[0026] Specifically, the buckle includes any one of the following: a press-type elastic buckle, a flexible silicone strip buckle, and a magnetic elastic buckle.
[0027] Specifically, the structure of the snap fastener is not limited to one type, as long as it meets the following characteristics: (1) The constraint range of the snap fastener must strictly match the trajectory of the spinal cord fixation groove to ensure that the mouse spinal cord is confined within the groove throughout the entire process, with no space to escape from the groove. (2) The constraint pressure on the mouse spinal cord must be controlled within a range that does not damage the spinal cord structure or compress the axons, and the pressure distribution must be uniform with no local excessive compression. (3) Throughout the entire process of tissue fixation, dehydration, and clearing, the snap fastener must maintain its constraint effect to prevent the mouse spinal cord from shifting due to reagent buoyancy or operational vibration. (4) The snap fastener structure must be compatible with the grid design of the base, not obstructing the grid pores, and not affecting reagent penetration.
[0028] Specifically, when the buckle is a press-type elastic buckle, the positioning support unit includes a sliding block disposed at the bottom of the buckle body and a sliding track disposed on the base; the elastic constraint unit includes a pressure adjusting spring and a pressure head disposed inside the buckle body; the adapter connection unit includes a knob, which is mechanically coupled to the pressure adjusting spring to change the compression of the pressure adjusting spring in order to adjust the pressure applied to the rat spinal cord.
[0029] The aforementioned buckle body is a rigid, integrally molded component. All functional parts are directly mounted on its surface or internally, without undergoing elastic deformation; it only serves as a support and force transmission mechanism. Through the cooperation of the sliding block and sliding track, the buckle can move flexibly along the track while ensuring precise relative positioning between the buckle and the spinal cord fixation groove. The pressure adjusting spring is the core source of elastic force; the elastic force generated by its deformation is transmitted to the pressure head through the buckle body, forming constraint pressure on the rat's spinal cord. It is the core functional component for achieving gentle fixation and preventing entanglement. The mechanical coupling between the knob and the pressure adjusting spring can be a threaded connection. Rotating the knob changes the compression of the pressure adjusting spring, thereby adjusting the pressure applied to the rat's spinal cord without affecting the movement of the sliding block along the track.
[0030] Specifically, when the buckle is a flexible silicone strip buckle, the elastic constraint unit is a flexible silicone strip; the positioning support unit includes buckle connectors disposed at both ends of the flexible silicone strip and buckle grooves disposed on the base; the adapter connection unit is a detachable connection structure between the flexible silicone strip and the buckle connectors.
[0031] The aforementioned flexible silicone strip, due to its inherent softness, generates elasticity, conforming to the surface of the mouse spinal cord and applying uniform pressure to confine the spinal cord within the groove. The snap-fit connector engages with the groove, fixing the silicone strip above the spinal cord fixation groove and ensuring the strip is distributed along the groove's trajectory. The detachable connection structure can be the interlocking parts at both ends of the silicone strip, allowing for the replacement of silicone strips of different widths / thicknesses (adapting to different mouse spinal cord diameters). Simultaneously, the quick disassembly of the snap-fit connector and base enables portable installation and adjustment of the strip.
[0032] Specifically, when the buckle is a magnetic elastic buckle, the positioning support unit includes a magnetic base; the elastic constraint unit includes a metal spring and an arc-shaped pressure head; and the adapter connection unit is a buckle connection structure between the metal spring and the magnetic base.
[0033] The base includes a non-magnetic adsorption surface, and the magnetic base is fixed to the base by strong magnetic adsorption, allowing it to move and reposition freely along the spinal cord fixation groove. The elastic deformation of the metal spring generates pressure, which is transmitted to the mouse spinal cord through an arc-shaped pressure head, the arc design of which adapts to the cylindrical surface of the mouse spinal cord. The snap-fit connection structure allows for the replacement of metal springs with different elastic coefficients, while the detachable connection between the spring and the magnetic base facilitates cleaning and maintenance, achieving pressure adaptation and ease of operation.
[0034] According to one possible implementation of this disclosure, at least the following beneficial effects are achieved: The integrated connectivity and anatomically matched design of the brain fixation groove and spinal cord fixation groove disclosed herein allows the mouse brain and spinal cord to maintain a natural connection angle immediately after ex vivo, enabling complete fixation without severance. This eliminates the risk of misalignment during the severance-reassembly process and ensures the continuity of long-range neural circuits. The snap-fit fixation system secures the spinal cord along its entire trajectory within the spinal cord fixation groove, stably confining it within the spiral groove and completely preventing it from floating or becoming entangled in the fixation fluid, thus ensuring the accuracy of neural circuit tracking.
[0035] This invention utilizes an integrated design of a brain bionic groove and a spiral bionic groove for the spinal cord. Without the need for manual adjustment of the orientation, the mouse brain can be directly embedded into the pre-set brain fixation groove, and the spinal cord naturally coils along the spiral groove and seamlessly connects with the end of the brainstem. The entire process does not require manual cutting or splicing, achieving one-step fixation and significantly improving operational efficiency.
[0036] The anatomically adapted biomimetic grooves and standardized pressure of the snap-fit mechanism ensure complete uniformity in the fixation shape and orientation of different samples. Regardless of the operator's experience, zero-difference fixation can be achieved through the physical structure of the device, providing a reliable technical foundation for high-quality, repeatable, three-dimensional continuous reconstruction of long-range brain-spinal cord circuits. The mesh-like base allows reagents to penetrate the sample from 360°, ensuring uniform processing of brain and spinal cord samples throughout the fixation, dehydration, and clearing processes, avoiding problems such as slice fragmentation and weak imaging signals caused by uneven processing.
[0037] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description
[0038] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.
[0039] Figure 1 A top view of the fixing device in an embodiment of this disclosure is shown; Figure 2 A three-dimensional structural schematic diagram of the fixing device in an embodiment of this disclosure is shown; Figure 3 A side view of the snap-fit fixing system in an embodiment of this disclosure is shown; Figure 4 A top view of the first and second latches in an embodiment of this disclosure is shown.
[0040] Figure label: 1-Base; 2-Brain fixation groove; 3-Spinal cord fixation groove; 4-First buckle; 41-First buckle body; 42-First sliding block; 43-First sliding track; 44-First pressure head; 5-Second buckle; 51-Second buckle body; 52-Second sliding block; 53-Second sliding track; 54-Second pressure head. Detailed Implementation
[0041] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.
[0042] Currently, the processing of long segments of rat brain and spinal cord tissue relies on manual truncation and splicing, resulting in poor consistency, uncontrolled length, and structural distortion. This disclosure standardizes the entire pretreatment process by using a specialized mold in the initial stage of tissue fixation to fix the relative position of the rat brain and intact spinal cord in one go. The biomimetic groove and snap-fit design ensures that each sample is fixed in the same shape; the mold structure defines the coiling path of the spinal cord, making the embedding length controllable and repeatable; the preset coiling path and snap-fit stabilize the rat spinal cord in a predetermined position, preventing distortion and ensuring the accuracy of axon tracking.
[0043] The following examples illustrate this in detail.
[0044] Example This embodiment provides a fixation device for a mouse brain-spinal cord sample, the structure of which is as follows: Figure 1 and Figure 2 As shown. The rat here can be any kind of rodent, such as a mouse, a rat, a hamster, etc. In this embodiment, a mouse is selected. The fixation device includes a base 1, a brain fixation groove 2 and a spinal cord fixation groove 3 disposed on the base 1, and the brain fixation groove 2 and the spinal cord fixation groove 3 are connected.
[0045] The brain fixation groove 2 is a biomimetic groove adapted to the hemispherical anatomical contour of the mouse brain, used to accommodate the lateral hemisphere of the mouse brain and expose the brainstem end of the mouse brain; the size of the brain fixation groove 2 is designed according to the size of the lateral hemisphere of the mouse brain. In this embodiment, a mouse is selected, and according to the size of its lateral hemisphere, the length of the brain fixation groove 2 is set to 20mm, the width is set to 8mm (at the maximum diameter), and the depth is set to 5mm.
[0046] The spinal cord fixation groove 3 is a spiral-shaped biomimetic groove adapted to the lateral anatomical contour of the mouse spinal cord, used to accommodate the side of the mouse spinal cord and maintain a natural connection angle between the mouse spinal cord and the brainstem. In this embodiment, a mouse was selected, and based on the size of its spinal cord, the total length of the spinal cord fixation groove 3 was set to 60 mm, the width to 1 mm, and the depth to 1 mm.
[0047] A transition arc with a radius of 2-3 mm is provided at the connection between the brain fixation groove 2 and the spinal cord fixation groove 3. This transition arc is used to smoothly connect the end of the mouse brain's brainstem with the beginning of the mouse spinal cord, avoiding bending of nerve fibers at the connection site. In this embodiment, the radius of the transition arc is 3 mm.
[0048] The base 1, brain fixation groove 2, and spinal cord fixation groove 3 are integrally molded. The integral molding method includes either precision injection molding or CNC milling. Specifically, if precision injection molding is chosen, the shape of the brain fixation groove 2 and spinal cord fixation groove 3 is designed as a mold cavity, and the grooved base is directly injection molded, with no seam between the groove and the base body. If CNC milling is chosen, the integral base is first machined, and then grooves matching the anatomical contours of the brain and spinal cord are milled on the base surface using a precision milling cutter. This embodiment uses precision injection molding. The brain fixation groove 2 and spinal cord fixation groove 3 are directly molded onto the base 1, and their relative positions are ensured by machining precision, avoiding misalignment of the brain-spinal cord connection caused by assembly errors in traditional separate spliced grooves. The seamless integral structure prevents the fixation groove from falling off or shifting during sample processing, and also prevents reagent residues in the splicing gaps from causing sample contamination, meeting the standardization and cleanliness requirements of experimental operations.
[0049] The material of base 1 is selected from at least one of polycarbonate and polytetrafluoroethylene, and polytetrafluoroethylene is selected here. Base 1 has a mesh structure, from... Figure 2 As can be seen, the base 1 is a cube with a high porosity mesh structure. The mesh holes are square. The high porosity design allows the tissue fixed on the base 1 to be fully penetrated by the reagent from all directions when the reagent is immersed in it, ensuring that the brain and spinal cord samples can be processed uniformly and thoroughly, thus improving the quality of slicing and imaging.
[0050] like Figure 2 and Figure 3As shown, the fixation device also includes a snap-fit fixation system. This system is positioned along the trajectory of the spinal cord fixation groove 3 to confine the mouse spinal cord within it. Specifically, it is positioned along the radial trajectory of the groove 3 (referring to the ray direction extending outward from the spiral center; each spiral groove has its corresponding radial ray, and these rays together constitute the radial trajectory system of the spiral groove). This system complements the spiral shape of the groove itself, perfectly constraining the spiral trajectory. The snap-fit fixation system includes several snaps, with a spacing of 5-10 mm between adjacent snaps. The snap-fit fixation system is designed to stably confine the mouse spinal cord sample within the spinal cord fixation groove 3 through constraint pressure, preventing it from floating, entangled, rotating, or structurally damaged during fixation, dehydration, and other processes, while also adapting to the anatomical morphology of the mouse spinal cord sample. The snap-fit fixing system of this embodiment includes two snaps: a first snap 4 and a second snap 5, with a distance of 5mm between them. Both snaps extend along the radial direction of the spiral groove, with one end of each snap pointing towards the center region of the spiral groove (i.e., the starting point of the radial line), and the other end extending outward along the radial line, covering one or two turns of the spiral groove. Each snap includes a positioning support unit, an elastic constraint unit, and an adapter connection unit. The positioning support unit is connected to the base 1 to fix the snap to the base 1; the elastic constraint unit provides elastic pressure to confine the mouse spinal cord within the spinal cord fixation groove 3; and the adapter connection unit connects the positioning support unit and the elastic constraint unit. The snaps may include any one of the following: a press-type elastic snap, a flexible silicone strip snap, or a magnetic elastic snap. In this embodiment, both the first snap 4 and the second snap 5 are press-type elastic snaps, with the specific structure as follows: Figure 4 As shown.
[0051] The positioning support unit of the first buckle 4 includes a first sliding block 42 disposed at the bottom of the first buckle body 41 and a first sliding track 43 disposed on the base 1. The first buckle body 41 is a rigid component formed integrally, and all functional components are directly installed on its surface or inside, without undergoing elastic deformation, only serving as support and force transmission. Through the cooperation of the sliding block and the sliding track, the first buckle 4 can move flexibly along the track, while ensuring the precise relative position of the first buckle 4 and the spinal cord fixation groove 3. The elastic constraint unit includes a first pressure adjusting spring (not shown in the figure) and a first pressure head 44 disposed inside the first buckle body 41. The first pressure adjusting spring is the core source of elastic force. The elastic force generated by its deformation is transmitted to the first pressure head 44 through the first buckle body 41, forming constraint pressure on the rat spinal cord, which is the core functional component for achieving gentle fixation and preventing entanglement. The adapter connection unit includes a first knob (not shown in the figure), which is mechanically coupled to a first pressure adjusting spring. In this embodiment, the mechanical coupling adopts a threaded connection to change the compression of the first pressure adjusting spring in order to adjust the pressure applied to the rat spinal cord.
[0052] The positioning support unit of the second buckle 5 includes a second sliding block 52 disposed at the bottom of the second buckle body 51 and a second sliding track 53 disposed on the base 1. The second buckle body 51 is a rigid component formed as a whole, and all functional components are directly installed on its surface or inside, without undergoing elastic deformation, only serving as a support and force transmission function. Through the cooperation of the sliding block and the sliding track, the second buckle 5 can move flexibly along the track, while ensuring the precise relative position of the second buckle 5 and the spinal cord fixation groove 3. The elastic constraint unit includes a second pressure adjusting spring (not shown in the figure) and a second pressure head 54 disposed inside the second buckle body 51. The second pressure adjusting spring is the core source of elastic force. The elastic force generated by its deformation is transmitted to the second pressure head 54 through the second buckle body 51, forming a constraint pressure on the rat spinal cord, which is the core functional component for achieving gentle fixation and preventing entanglement. The adapter connection unit includes a second knob (not shown in the figure), which is mechanically coupled to a second pressure adjusting spring. In this embodiment, the mechanical coupling is a threaded connection used to change the compression of the second pressure adjusting spring in order to adjust the pressure applied to the rat spinal cord.
[0053] Figure 2 and Figure 4 As shown, the second clip 5 is used to restrict the mouse spinal cord in two loops of the spinal cord fixation groove 3, while the first clip 4 is used to restrict the mouse spinal cord in one loop of the spinal cord fixation groove 3. Therefore, the size of the second clip 5 is correspondingly larger than the size of the first clip 4, and the specific size is determined according to actual needs. The aforementioned first clip 4 and second clip 5 completely cover the slender spinal cord in the spinal cord fixation groove 3, effectively preventing the axonal fibers from rotating and twisting due to floating and entanglement in the reagent, thus ensuring the continuity of neural circuit tracking.
[0054] In summary, this embodiment uses a physical mold to fix the three-dimensional spatial relationship between the mouse brain and the intact spinal cord during the initial fixation stage of sample processing. Specifically, this is manifested in: (1) Morphological maintenance: using biomimetic grooves, the original connection morphology between the brainstem end and the spinal cord beginning end is maintained immediately after detachment, avoiding stretching or twisting. (2) Standardized coiling: through a pre-set involute spiral groove and a snap-locking system, long segments of the spinal cord are coiled in a standardized, non-rotating arc, eliminating random deformation caused by manual operation. The combination of the above two points ensures accurate three-dimensional alignment at the mouse brain-spinal cord connection, guarantees morphological consistency between samples, achieves precise control of the embedding length, and fundamentally prevents spinal cord entanglement and rotation, thus providing a reliable technical foundation for achieving high-quality, repeatable three-dimensional reconstruction of long-range brain-spinal cord circuits.
[0055] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.
[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.
[0057] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.
Claims
1. A device for fixing a rat brain-spinal cord sample, characterized in that, The fixation device includes a base, a brain fixation groove and a spinal cord fixation groove disposed on the base, wherein the brain fixation groove and the spinal cord fixation groove are in communication; The brain fixation groove is a biomimetic groove adapted to the anatomical contour of the lateral hemisphere of the mouse brain, used to accommodate the lateral hemisphere of the mouse brain and expose the brainstem end of the mouse brain. The spinal cord fixation groove is a spiral-shaped biomimetic groove adapted to the lateral anatomical contour of the mouse spinal cord, used to accommodate the side of the mouse spinal cord and maintain a natural connection angle between the mouse spinal cord and the end of the brainstem.
2. The fixing device according to claim 1, characterized in that, The brain fixation groove has a length of 15-25 mm, a width of 8-15 mm, and a depth of 5-8 mm.
3. The fixing device according to claim 1, characterized in that, The total length of the spinal cord fixation groove is 60~100mm, the width is 1~2mm, and the depth is 1~2mm.
4. The fixing device according to claim 1, characterized in that, The connection between the brain fixation groove and the spinal cord fixation groove is provided with a transition arc with a radius of 2-3 mm, which is used to smoothly connect the end of the brainstem of the mouse brain with the beginning of the mouse spinal cord, and avoid the bending of nerve fibers at the connection site.
5. The fixing device according to claim 1, characterized in that, The base, the brain fixation groove, and the spinal cord fixation groove are integrally molded, and the integral molding method includes any one of precision injection molding and CNC milling.
6. The fixing device according to claim 1, characterized in that, The material of the base is selected from at least one of polycarbonate and polytetrafluoroethylene; The base has a grid-like structure with square or regular hexagonal grid holes.
7. The fixing device according to any one of claims 1 to 6, characterized in that, The fixation device further includes a snap-fit fixation system, which is arranged along the trajectory of the spinal cord fixation groove to restrict the mouse spinal cord within the spinal cord fixation groove; the snap-fit fixation system includes a plurality of snaps, with a spacing of 5-10 mm between adjacent snaps.
8. The fixing device according to claim 7, characterized in that, The snap-fit fixing system is arranged along the radial trajectory of the spinal cord fixation groove.
9. The fixing device according to claim 7, characterized in that, The buckle includes a positioning support unit, an elastic constraint unit, and an adapter connection unit; the positioning support unit is connected to the base and is used to fix the buckle on the base; the elastic constraint unit is used to provide elastic pressure to restrict the rat spinal cord within the spinal cord fixation groove; the adapter connection unit is used to connect the positioning support unit and the elastic constraint unit.
10. The fixing device according to claim 9, characterized in that, The buckle includes any one of the following: a press-type elastic buckle, a flexible silicone strip buckle, and a magnetic elastic buckle; The positioning support unit of the press-type elastic buckle includes a sliding block disposed at the bottom of the buckle body and a sliding track disposed on the base; the elastic constraint unit includes a pressure adjusting spring and a pressure head disposed inside the buckle body; the adapter connection unit includes a knob, which is mechanically coupled to the pressure adjusting spring and is used to change the compression of the pressure adjusting spring to adjust the pressure applied to the rat spinal cord.