Small animal in-vitro tissue CT scanning tubing method and auxiliary tool

Abstract

The invention relates to a small animal in-vitro tissue CT scanning tubing method and assistive device, and the method comprises the following steps: trimming a sponge into a rectangle, and soaking the sponge in a stationary liquid; tubing area lines are drawn on the paper, and a rectangular tubing equal-size area is defined by the tubing area lines; parallel tissue marking lines are drawn in the length direction in the tubing equal-size area, the tissue marking lines mark groups of tissues, and a preservative film completely covering the tubing equal-size area is placed on paper; placing the sponge on the preservative film; according to the tissue marking lines, tissue grooves are cut in the positions of the sponges corresponding to all the groups of tissues; the tissue is placed in the tissue groove; pressing the preservative films at the two ends to roll the sponge into a cylinder; the cylinder is fixed according to the viscosity of the preservative film; and the cylinder is arranged in the scanning tube. Compared with the prior art, the time spent on assembly is short, the scanning time of multiple tissues is shortened, and the phenomenon that the imaging quality is affected due to excessive stationary liquid residues is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of animal tissue medical imaging, and relates to a small animal ex vivo tissue CT scanning tube installation method and auxiliary tools. Background Art

[0002] Micro-CT (micro computed tomography) can restore the internal microscopic structure through 3D imaging technology without destroying the ex vivo tissue. The resolution is often at the micron level, and it is widely used in biomedical research. The working principle of micro-CT is to use a microfocus X-ray tube to scan and project the layers of each part of the tissue sample. When using it, it is necessary to select a scanning tube of appropriate size and load the ex vivo tissue sample. There are differences in the scanning direction of different brands of micro-CT. In order to obtain good scanning results, researchers often need to spend a lot of energy to prepare the ex vivo tissue to ensure that the direction and position of the sample after loading the tube are not significantly shifted. In addition, during the preservation and preparation of the sample, it is often necessary to soak the ex vivo tissue in a fixative. If there is too much residual fixative during loading, it will overflow from the scanning tube, causing corrosion or damage to the precision parts, affecting the normal operation and imaging quality of the instrument, and causing inaccurate imaging data. When there are too many samples to be scanned, the scanning time is often longer. Long-term operation may cause the instrument to overheat, affecting its service life, causing the sample to dry out and affecting subsequent experiments.

[0003] Patent CN212975167U discloses a mouse ex vivo skull sample box set for Micro-CT scanning, comprising at least two sample box frames, sample covers respectively covering the upper and lower sides thereof, side panel connecting components adhered to the sample box frames and the sample covers on opposite sides, and sample clamping layers respectively arranged in the sample box frames, a side panel connecting component being shared by adjacent sample box frames, and the sample box frames and the sample covers being hingedly arranged via the side panel connecting components; the low-density sample clamping layer comprises a sample moisturizing pad and a sample buffer layer, the sample moisturizing pad comprises a sample pad body filling the bearing panel and a skull groove fitting the contour of the mouse skull, a dome-shaped skull support is arranged on the skull groove corresponding to the inner surface of the skull base of the mouse ex vivo skull, a groove for accommodating the contour of the mouse skull is formed between the skull support and the skull groove, and a support groove is arranged on the sample buffer layer corresponding to the skull support for fixing the mouse ex vivo skull in the low-density sample clamping layer. However, this patent is not applicable to all models of micro-CT, especially small animal micro-CT with relatively high accuracy, which often have matching sample tubes or devices, which are placed inside the machine for scanning through interlocking, etc.; in addition, this patent does not have components that can be fixed to the machine, and slight vibrations may occur during the operation of the machine, causing slight displacement of the patent, which will lead to a decrease in the accuracy of the sample scanning results.

[0004] Patent CN220019436U discloses a small animal CT scanning tube fixing device, including an outer cylinder, the material of the outer cylinder is a transparent material, a chassis is fixed to the bottom of the outer cylinder, a CT imager is arranged at the bottom of the chassis, a partition placement mechanism is arranged inside the outer cylinder, the interior of the partition placement mechanism includes an inner cylinder component, an isolation plate and a plate groove, a fixing mechanism is arranged inside the partition placement mechanism, the fixing mechanism is composed of a rubber sleeve, a connecting assembly and a rubber protrusion, the chassis and the CT imager are detachably connected through a positioning and mounting mechanism, the interior of the positioning and mounting mechanism includes a screw hole and a positioning and mounting component. However, the partition mechanism set up in this patent also limits the sample size. Samples that exceed the partition size cannot be placed. Although long strip samples (length less than the cross-sectional diameter) can be placed with the long axis parallel to the tube axis, due to the scanning principle of micro-CT (i.e. scanning the cross-section layer by layer from top to bottom or from bottom to top, scanning where there are samples and skipping where there are no samples), this will increase the scanning time and cost and shorten the service life of the machine, especially when the number of scanned samples is small; in addition, this patent has no top cover, and the heat generated during the operation of the machine may cause the sample to dry out, thereby affecting subsequent experiments. Summary of the invention

[0005] The purpose of the present invention is to overcome at least one defect of the above-mentioned prior art and provide a small animal ex vivo tissue CT scanning tube installation method and auxiliary equipment. The present invention takes a short assembly time, reduces the scanning time of multiple tissues, and there will not be too much residual fixative to affect the imaging quality.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a method for tube loading for CT scanning of ex vivo tissue of small animals, the method comprising the following steps:

[0008] S1. Trim the sponge into a rectangular shape and soak it in the fixative solution;

[0009] S2. Draw a pipe loading area line on the paper, and the pipe loading area line encloses a rectangular large pipe loading area;

[0010] S3. Draw parallel tissue marking lines in the length direction of the large area such as the tube, the tissue marking lines mark the tissue groups, and place a plastic wrap on the paper to completely cover the large area such as the tube;

[0011] S4. Place the sponge on the plastic wrap;

[0012] S5. Cut out tissue grooves at the positions of the sponges corresponding to each group of tissues according to the tissue marking lines;

[0013] S6, placing the tissue in the corresponding tissue slot;

[0014] S7. Press the plastic wrap at both ends to roll the sponge into a cylinder;

[0015] S8. Fix the cylinder by using the slight stickiness of the plastic wrap to stabilize the cylinder so that it does not fall apart;

[0016] S9. The cylinder is placed in the scanning tube.

[0017] As a preferred technical solution, in step S1, the sponge is a water-absorbing sponge selected from microfiber sponge, natural sponge, honeycomb sponge, and foam sponge.

[0018] Furthermore, in step S1, the cutting length of the sponge is set to the corresponding length of the scanning tube, and the width is set to the cross-sectional area of ​​the scanning tube divided by the cutting thickness of the sponge, because after the sponge is rolled up, the product of the cutting width and thickness of the sponge should just fill the cross-section of the scanning tube, and the support force provided by the expansion of the sponge and the friction of the sponge can reduce the occurrence of displacement.

[0019] Furthermore, in step S2, the length of the large area including the tube is set to the corresponding length of the scanning tube, and the width is set to the cross-sectional area of ​​the scanning tube divided by the cutting thickness of the sponge.

[0020] Furthermore, in step S3, the spacing between each tissue marking line is 10-25% of the cutting length of the sponge.

[0021] As a preferred technical solution, the spacing between each tissue marking line in step S3 is 0.7-1.3 cm.

[0022] Different scanning tubes of different brands of micro-CT have different scanning areas. Large-size scanning tubes are suitable for large samples, and small-size scanning tubes are suitable for small samples. Under the same scanning parameters, the accuracy of large-size scanning tubes is lower than that of small-size scanning tubes, and the imaging is relatively more blurred. The inter-group spacing should be determined according to the scanning area of ​​the scanning tube, the size and number of samples. If the inter-group spacing of samples is too small, it will cause image overlap or blur, affecting the image quality. If the inter-group spacing of samples is too large, the samples at both ends will exceed the scanning area. The inter-group spacing range provided here is a range that is easier to operate under the naked eye. It is for reference only and can be changed accordingly in different situations. For example: a certain scanning tube can scan 4-6 rows of samples, but researchers only need to scan 2 rows. At this time, the inter-group spacing can be relaxed to 15-40% of the cutting length of the sponge.

[0023] As a preferred technical solution, the distance between groups can be relaxed to 1-2 cm.

[0024] Furthermore, in step S4, the sponge is squeezed until no fixative solution drips, so as to prevent the fixative solution from accumulating in the scanning tube and leaking into the micro-CT machine.

[0025] Furthermore, in step S5, the spacing between each tissue groove in the same group is 5-20% of the cutting width of the sponge.

[0026] As a preferred technical solution, the spacing between each tissue groove in the same group in step S5 is 0.3-0.7 cm.

[0027] Different scanning tubes of different brands of micro-CT have different scanning cross-sections. Large-size scanning tubes are suitable for samples with larger cross-sections, and small-size scanning tubes are suitable for samples with smaller cross-sections. The intra-group spacing should be determined based on the scanning cross-section of the scanning tube, the maximum cross-section of the sample, and the number of samples. If the intra-group sample spacing is too small, it will cause image overlap or blur, affecting the image quality. If the intra-group sample spacing is too large, it will lead to a reduction in the number of samples placed. The intra-group spacing range provided here is a range that is easier for the human eye to operate. It is for reference only and can be changed accordingly in different situations. For example: a scanning tube can scan 2-4 columns of samples, but researchers only need to scan 2 columns. At this time, the intra-group spacing can be relaxed to 25-40% of the cutting length of the sponge.

[0028] As a preferred technical solution, the spacing within the group can be relaxed to 1-1.5 cm.

[0029] Furthermore, in step S5, notches are cut at the corners of the sponge to distinguish the direction.

[0030] Furthermore, in step S7, the plastic wrap is trimmed so that it is slightly larger than the sponge, and the position of the plastic wrap is adjusted so that the portion of one side of the plastic wrap that exceeds the long side of the sponge just covers the first column of tissue. This can ensure that the tissue does not shift during the process of rolling the sponge, that is, the only exposed surface of the tissue is covered with the plastic wrap. When the plastic wrap is pressed tightly, there is no space for the tissue to shift. Similarly, during the process of rolling the sponge, the plastic wrap is rolled in as a covering surface. Not only will the subsequent columns of tissue not shift, but the plastic wrap is also not easy to fall off.

[0031] As a preferred technical solution, in step S8, the plastic wrap at both ends of the sponge is knotted to form a sealed space and then the excess part is cut off.

[0032] Furthermore, in step S8, adhesive tape is used to fix the cylinder. If the slight viscosity of the plastic wrap is stable enough to prevent the cylinder from falling apart, there is no need to fix it.

[0033] As a preferred technical solution, the tape is a low-viscosity tape selected from masking tape, non-woven tape, polyethylene tape, kraft paper tape, and cloth-based tape.

[0034] As a preferred technical solution, in step S9, after wiping off excess moisture from the cylinder with a paper towel, the tubes are installed counterclockwise from top to bottom, or clockwise from bottom to top.

[0035] As a preferred technical solution, in step S9, the cylinder is loaded into a scanning tube inserted into a tube loading slot.

[0036] As a preferred technical solution, in step S9, due to the elastic recovery property of the sponge, the cross-section of the sponge prepared in the previous step after rolling up should be larger than the scanning tube when viewed with the naked eye, and the operator needs to use appropriate force to load the sponge into the scanning tube; after the sponge is completely loaded into the scanning tube, the support force provided by the expansion of the sponge and the friction of the sponge can reduce the occurrence of displacement.

[0037] As a preferred technical solution, after step S9, the tape and plastic wrap are removed after the tissue scanning is completed, and the tissue is recovered for subsequent experiments.

[0038] One of the technical solutions of the present invention is to provide a small animal ex vivo tissue CT scanning tube loading auxiliary tool, the auxiliary tool uses the method to assist the small animal ex vivo tissue CT scanning tube loading, the auxiliary tool includes a plastic wrap and a sponge, the sponge is provided with a plurality of groups of tissue grooves, each group has a plurality of groups, and the tissue is placed in the corresponding tissue groove;

[0039] The sponge is covered with a plastic wrap on one side of the sponge and the first row of tissue grooves on the other side, and the sponge is rolled into a cylinder with the plastic wrap.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The method of the present invention is simple and easy to operate, the materials used are common and low-cost, the technical sensitivity is low (the operation is simple and easy to understand, and good results can be achieved with simple practice (it is difficult to load tissues into tubes before scanning micro-CT. When the operator loads a tissue into the sponge tank, the previously loaded tissue falls off, and the operator needs to spend a lot of time to arrange the positions of various tissues. However, with the help of the method of the present invention, the difficulty of this process is greatly reduced, and loading the tube becomes much simpler)) and the assembly time is short;

[0042] (2) The method of the present invention optimizes tissue arrangement and can minimize scanning time while scanning multiple tissues;

[0043] (3) The tissue has good retention in the method of the present invention, and high-quality imaging results can be obtained. At the same time, the water absorption of the sponge can ensure the moistening of the tissue, and there will not be too much residual fixative to affect the imaging quality;

[0044] (4) The process of recovering tissue after scanning by the method of the present invention is simpler and less likely to confuse the groups. Corresponding tissues are recovered in different grouping orders, reducing machine wear and tear and scientific research costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1This is a schematic diagram of a first process of a method for tube loading for CT scanning of ex vivo tissue of a small animal according to an embodiment of the present invention;

[0046] Figure 2 This is a second flow chart of the method for tube loading for CT scanning of ex vivo tissue of small animals according to an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of a third process of the method for tube loading for CT scanning of ex vivo tissue of small animals in an embodiment of the present invention;

[0048] Figure 4 Schematic diagram of the fourth process of the method for tube loading for CT scanning of ex vivo tissue of small animals in an embodiment of the present invention.

[0049] Description of the markings in the figure:

[0050] 1—tube loading area line, 2—tube loading and other large areas, 3—plastic wrap, 4—tissue marking line, 5—sponge, 6—tissue groove, 7—notch, 8—tissue. DETAILED DESCRIPTION

[0051] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0052] Unless otherwise specified, the equipment used in the following examples are all conventional equipment in the art; the reagents used are all commercially available products or prepared by conventional methods in the art unless otherwise specified. Anything not described in detail in the following examples can be achieved by conventional experimental means in the art.

[0053] Example:

[0054] A small animal ex vivo tissue CT scanning tube loading auxiliary tool, comprising a sheet of A4 paper, a roll of plastic wrap, a ruler, a roll of masking tape, a ballpoint pen (or gel pen), a microfiber sponge, a pair of ophthalmic forceps and ophthalmic scissors, a scanning tube, and a tube loading slot;

[0055] The corresponding length of the scanning tube is 5.5cm, and the cross-sectional area is 2cm 2 ;

[0056] Draw four tube-loading area lines 1 on paper using a ruler and pen. The four tube-loading area lines 1 enclose a rectangular tube-loading equal area 2. The length of the tube-loading equal area 2 (the cutting length of the sponge 5) is set to the corresponding length of the scanning tube, 5.5 cm, and the width (the cutting width of the sponge 5) is set to the cross-sectional area of ​​the scanning tube, 2 cm. 2Divide by the cutting thickness of the sponge 5 0.5cm to get 4cm, because after the sponge 5 is rolled up, the product of the cutting width and thickness of the sponge 5 should just fill the cross section of the scanning tube, and the support force provided by the expansion of the sponge 5 and the friction force of the sponge 5 can reduce the displacement;

[0057] Draw four organization marking lines 4 in the large area 2 such as the tube installation using a ruler and a pen, and the organization marking lines 4 mark the grouping of the organization 8;

[0058] The sponge 5 is provided with 4 groups of 16 tissue grooves 6, 4 in each group. The tissue grooves 6 and the notches 7 for distinguishing directions are cut out on the sponge 5 using scissors. The tissue 8 is placed in the corresponding tissue groove 6 using forceps. The tissue 8 is the maxillary bone of a mouse.

[0059] The sponge 5 is covered with one side of the sponge 5 and the first row of tissue grooves 6 on the other side by the cling film 3. The sponge 5 is rolled into a cylinder by the cling film 3 and loaded into a scanning tube inserted into the tube loading groove.

[0060] A method for CT scanning of ex vivo tissue of small animals, using the above-mentioned auxiliary device to assist in CT scanning of ex vivo tissue of small animals, and the specific steps are as follows:

[0061] S1, trim the sponge 5 into a rectangle with a width of 4 cm, a length of 5.5 cm, and a thickness of 0.5 cm, and immerse it in a fixing solution;

[0062] S2, such as Figure 1 As shown, four pipe-loading area lines 1 are drawn in the middle of the A4 paper, and the four pipe-loading area lines 1 enclose a rectangular large pipe-loading area 2 with a width of 4 cm and a length of 5.5 cm;

[0063] S3, draw four parallel tissue marking lines 4 in the length direction of the large area 2 for tube loading, the tissue marking lines 4 mark the grouping of tissue 8, the spacing between each tissue marking line 4 is 1 cm, and place a piece of plastic wrap 3 on the A4 paper to completely cover the large area 2 for tube loading;

[0064] S4, such as Figure 2 As shown, the sponge 5 is squeezed until no fixative solution drips and then placed on the plastic wrap 3 to prevent the fixative solution from accumulating in the scanning tube and leaking into the micro-CT machine;

[0065] S5, cut four tissue grooves 6 at the position of the sponge 5 corresponding to each group of tissues 8 according to the tissue marking line 4, the spacing between each tissue groove 6 in the same group is 0.5 cm, and if necessary, a notch 7 can be cut at the upper left corner (or upper right corner) of the sponge 5 to distinguish the direction;

[0066] S6, such as Figure 3 As shown, the tissue 8 is placed in the corresponding tissue groove 6;

[0067] S7, trim the cling film 3 so that the cling film 3 is slightly larger than the sponge 5, adjust the position of the cling film 3 so that the left side of the cling film 3 beyond the sponge 5 just covers the first row of tissues 8, so that the tissues 8 will not shift during the process of rolling the sponge 5, that is, the cling film 3 covers the only exposed surface of the tissues 8, and when the cling film 3 is pressed tightly, there is no space for the tissues 8 to shift. Similarly, during the process of rolling the sponge 5, the cling film 3 is rolled in as a covering surface, so that not only the subsequent rows of tissues 8 will not shift, but also the cling film 3 is not easy to fall off;

[0068] Press down the two ends of the plastic wrap 3 to roll the sponge 5 into a cylinder;

[0069] S8, such as Figure 4 As shown, tie a knot on the cling film 3 at both ends of the sponge 5 to form a sealed space, cut off the excess part, and use tape to fix the cylinder as needed. If the cling film 3 has a slight stickiness that is stable enough to prevent the cylinder from falling apart, it does not need to be fixed;

[0070] S9. Use a paper towel to wipe off excess moisture from the cylinder and then install the tube counterclockwise from top to bottom (clockwise from bottom to top).

[0071] Since the sponge 5 has elastic recovery properties, the cross-section of the sponge 5 prepared in the previous steps after rolling up should be larger than the scanning tube under the naked eye, and the operator needs to use appropriate force to load the sponge 5 into the scanning tube; after the sponge 5 is completely loaded into the scanning tube, the support force provided by the expansion of the sponge 5 and the friction force of the sponge 5 can reduce the displacement;

[0072] After the tissue 8 is scanned, the tape and the plastic wrap 3 can be removed, and the tissue 8 can be recovered for subsequent experiments.

[0073] Conventional tube loading method: After the tissue is embedded in a long strip of rigid plastic foam (the cross section of the foam strip is smaller than the cross section of the scanning tube, and the length is within the scanning area), a circle of transparent tape is wrapped around the outside, the tape at both ends is trimmed, and the moisture is wiped off with a paper towel before loading into the scanning tube;

[0074] Disadvantages of conventional tube loading methods: rigid plastic foam strips do not absorb water and cannot moisturize tissues; adhesive from the inner side of the tape may remain on the tissues, affecting subsequent recovery; the surface of the tape is smooth and rigid plastic foam strips may easily shift.

[0075] In the method of the present invention, there is a certain distance between groups of tissues and between multiple groups of tissues, and a group of tissues is basically located at the same level. While scanning multiple tissues, the scanning time is reduced as much as possible, so that scientific researchers can obtain experimental results more quickly after rapid assembly;

[0076] The sponge used therein has no X-ray opacity and high water absorption, so the method of the present invention can obtain high-quality imaging results while ensuring the moistening of the tissue, and there will not be too much residual fixative to affect the imaging quality;

[0077] The elastic recovery properties of the sponge, the combined use of plastic wrap and tape have a good retention effect, allowing the tissue to stay in the corresponding tissue groove without shifting;

[0078] Furthermore, since the adhesive tape and plastic wrap have low viscosity, they are easy to remove when recovering tissues and will not confuse tissue grouping, thus facilitating tissue recovery.

[0079] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for CT scanning of ex vivo tissue of small animals, characterized in that: The method comprises the following steps: S1, trim the sponge (5) into a rectangular shape and soak it in a fixing solution; S2, draw a pipe loading area line (1) on the paper, and the pipe loading area line (1) encloses a rectangular pipe loading area (2); S3, draw parallel tissue marking lines (4) in the length direction of the large area (2) such as the tube, the tissue marking lines (4) mark the groups of the tissue (8), and place a plastic wrap (3) on the paper to completely cover the large area (2) such as the tube; S4, placing the sponge (5) on the plastic wrap (3); S5, cutting out tissue grooves (6) at the positions of the sponges (5) corresponding to each group of tissues (8) according to the tissue marking lines (4); S6, placing the tissue (8) in the tissue tank (6); S7, pressing the two ends of the plastic wrap (3) to roll the sponge (5) into a cylinder; S8, fixing the cylinder according to the stickiness of the cling film (3); S9. The cylinder is placed in the scanning tube.

2. A method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S1, the cutting length of the sponge (5) is set to the corresponding length of the scanning tube, and the width is set to the cross-sectional area of ​​the scanning tube divided by the cutting thickness of the sponge (5).

3. The method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S2, the length of the large area (2) containing the tube is set to the corresponding length of the scanning tube, and the width is set to the cross-sectional area of ​​the scanning tube divided by the cutting thickness of the sponge (5).

4. The method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S3, the spacing between each tissue marking line (4) is 10-25% of the cutting length of the sponge (5).

5. The method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S4, the sponge (5) is squeezed until no fixative solution drips.

6. The method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S5, the spacing between each tissue groove (6) in the same group is 5-20% of the cutting width of the sponge (5).

7. The method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S5, notches (7) are cut out at the corners of the sponge (5).

8. The method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S7, the position of the cling film (3) is adjusted so that the portion of one side of the cling film (3) that extends beyond the long side of the sponge (5) just covers the first row of tissues (8).

9. The method for CT scanning of ex vivo tissue of small animals according to claim 1, characterized in that: In step S8, adhesive tape is used to fix the cylinder.

10. A small animal ex vivo tissue CT scanning tube loading auxiliary tool, characterized in that: The auxiliary tool adopts the method according to any one of claims 1 to 9 to assist in the CT scanning and tube loading of ex vivo tissues of small animals, the auxiliary tool comprises a plastic wrap (3) and a sponge (5), a plurality of groups of tissue grooves (6) are provided in the sponge (5), each group having a plurality of tissue grooves, and the tissues (8) are placed in the corresponding tissue grooves (6); The sponge (5) is covered with a preservative film (3) on one side of the sponge (5) and a first row of tissue grooves (6) on the other side. The sponge (5) is rolled into a cylinder by the preservative film (3).

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