EP0610527A1

EP0610527A1 - Embryo collector

Info

Publication number: EP0610527A1
Application number: EP93102018A
Authority: EP
Inventors: Christian J. Simmet; Ludwig O. Simmet
Original assignee: Minitueb Abfuell und Labortechnik GmbH and Co KG
Current assignee: Minitueb Abfuell und Labortechnik GmbH and Co KG
Priority date: 1993-02-09
Filing date: 1993-02-09
Publication date: 1994-08-17

Abstract

A device for filtering sensitive biological micro-entities, according to a special application animal embryos flushed from a donor animal uterus, the micro-entities appearing suspended in a flushing solution fron this flushing solution. The device (10) comprises a housing which includes an inlet chamber (22) and an outlet chamber (24), separated by a sheet of filter material (18) which allows the passage of the flushing solution but retains the biological micro-entities (72), an inlet tube (32) extending out of the outlet chamber. For keeping the micro-entities suspended in the solution until microscopic selection, the device (10) is designed for an operating position wherein the filter material (18) is vertically oriented, and in the outlet chamber (24) there is an overflow threshold (50, 52) between this chamber and the outlet tube (50).

Description

Field of the Invention

This invention relates to apparatus for collecting sensitive biological micro-entities as may generally be used in animal reproduction, a particular application being collecting and transporting the embryos or ova of mammals.

Background of the Invention

For centuries selective breeding techniques have been employed to generate animal offspring having preferred qualities such as size, productivity and temperament. Male animals having desirable genetic characteristics may naturally sire offspring by multiple females in a single season. In recent times artificial insemination techniques have made possible the generation of thousands of offspring from a single parent at locations throughout the world. To adequately exploit the genetic material of female animals without requiring the female fo give birth to all her offspring, a common practice is to inseminate the female by natural or artificial means and then extract the animal embryos at an age of three to five days. The extracted embryos are then typically frozen for shipment, processing, preservation or implantation at a later time.
It is well known in the art of animal husbandry to retrieve and collect mammalian embryos or ova from donor animals by flushing the animal's uterus with a solution and collecting the embryo bearing fluids, then passing the fluids through a filtration device in which the embryos are collected. It is absolutely necessary that the embryos stay suspended in the solution and may not come into the situation of a dry ambient. Typical prior art devices require the collected embryos and solution to be transferred in the laboratory to a petri dish for examination beneath a microscope and removal and packaging of the embryos. Transfer of fluid from the collecting container to the petri dish is undesirable as embryos may be lost or damaged in the transfer. Some embryo collectors employ collection vessels which are transparent and which have a flat base to permit positioning on a microscope table, however these known devices are cumbersome and have filter openings formed in the vessel sidewall or base which are of limited extent and which may allow embryos to be trapped without liquid suspension. Furthermore, conventional adhesive attachment of filters across outlet openings leaves undesirable crevices in which embryos may become trapped. Frequently the collection of the animal embryos is performed on site in a barn. This subjects the embryos to the ambient temperature which may be lower than the temperature of the donor animal.
To maintain maximum embryo viability and health, it is desirable to keep the embryos at a approximate body temperature of the donor during the collection and transportation procedure since the collection alone may take one-half to one hour and may be performed in a barn in cold weather.
What is needed is a compact and easy to use embryo transfer and collection device which efficiently separates the embryos from the carrier fluid without subjecting them to damage, which is protected from contamination and which may preferable be placed directly under a microscope for extraction of the embryos.

Summary of the Invention

The above stated need is met by a device as defined in claim 1, which device in use is to be oriented so as to have the filter material sheet vertical and being traversed by the solution in a generally horizontal direction.
According to a preferred embodiment thereof, in the use of an animal embryo collector, this has a dish, a lid and a sheet of filter material interposed between the lid and the dish. The dish has a cylindrical sidewall which extends upwardly from a planar bottom which is adapted to be placed on a microscope stage for viewing and selecting the animal embryos. An inlet tube extends through the dish sidewall and opens into the dish to discharge a flushing solution containing embryos into the dish. The lid has to top with downwardly extending sidewalls. The lid is engageable with the dish to form a fluid-tight compartment. An outlet tube extends out of the lid and is adapted to direct flushing solutions out of the lid. The outlet tube has a fluid outlet opening communicating with the interior of the lid. A sheet of filter material is clamped between the dish and the lid. The filter has a pore size sufficient to prevent passage of an embryo from the dish while allowing the passing of flushing fluid into the lid. A retaining ring clamps the filter sheet to the lid. The dish engages with the lid beneath the retention fitting.
In use, the filter is positioned in a vertical orientation with the inlet tube oriented toward the donor animal. The inlet tube may be attached to a balloon catheter which is placed in the animal's uterus. The flushing fluid volume is controlled in a conventional manner by valve feeding the balloon catheter. The flushing fluid containing embryos enters into the dish through the inlet tube and passes across the filter into the lid. Embryos are collected in the dish with the waste fluids exiting through the outlet tube.
The positioning of the overflow, e.g. of the inlet opening of the outlet tube with respect to the lid sidewall, permits the fluid volume retained within the device to be set at a desired level. Inlet and outlet tubes are positioned with respect to one another to determine a fluid collection volume within the device. At all times during the embryo collection procedure the embryos reside in a liquid volume.
To extract collected embryos the device is positioned horizontally and the lid and filter material removed. Embryos may then be located and extracted under a microscope.
Thus, the invention provides an embryo collection device which permits a volume of fluid to be retained within the device, this volume to be set at a desired level. This avoids damage to the embryos during collection.
According to preferred embodiments, the device can easily be constructed so that it will not leak during collection, that it may be positioned under a microscope for extraction of embryos without transfer to a separate vessel, that it is sufficiently compact and leakproof to allow it to be held in an operator's pocket to keep the collected embryos warm, and that it is generally reusable and sterilizable.
Further objects, features, and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

Fig. 1 is an exploded isometric view of an embodiment of the embryo collector of the present invention.
Fig. 2 is a front elevational view of the device of Fig. 1 shown in relation to a donor animal.
Fig. 3 is an enlarged front elevational view of the device of Fig. 2 illustrating two halves rotated to increase the volume of liquid retained.
Fig. 4 is an enlarged front elevational view of the device of Fig. 3 illustrating the two halves rotated to retain a still greater volume of liquid.
Fig. 5 is a cross-sectional view of the embryo transfer device of Fig. 2 in a plane V-V in Fig. 3 showing the collection and filtration on embryo containing solutions during a collection procedure.
Fig. 6 is a cross sectional view of the embryo collector of Fig. 5 showing the device in a horizontal orientation preparatory to viewing under a microscope.
Fig. 7 is a cross sectional view of a dish portion of the device of Fig. 6 on a microscope viewing stand, with the collection probe and the microscope objective shown in phantom.
Fig. 8 is an exploded isometric view of an alternative embodiment embryo collector of this invention utilizing a disposable petri dish.
Fig. 9 is an exploded isometric view of another alternative embodiment embryo collector of this invention.
Fig. 10 is an exploded isometric view of yet another alternative embodiment of the embryo collector of this invention.
Fig. 11 is an exploded isometric view of still another alternative embodiment of the embryo collector of the present invention.
Fig. 12 is a fragmentary perspective view of the device of Fig. 1 being inserted within the pocket of an insulating garment.
Fig. 13 is an isometric view of the device of Fig. 1 contained within a thermoformed clam shell package.
Fig. 14 is an exploded isometric view of an alternative embodiment of the collector of the present invention having a compartmented sleeve for retaining fluid from which mucus has been filtered out.
Fig. 15 is a cross-sectional view of the compartmented sleeve of the collector of Fig. 14 with liquid retained therein.
Fig. 16 is a cross-sectional view of the dish of the collector of Fig. 14.
Fig. 17 is a cross-sectional view of the collector of Fig. 14 in the process of filtering an embryo and mucus containing fluid.

Description of the Preferred Embodiments

An embryo collector 10 is shown in Fig.s 1 to 6. As best shown in Fig. 1, the collector 10 has a transparent plastic embryo retaining dish 12 which engages with a plastic lid 14 to form a fluid tight filtration vessel 16. A sheet of filter material 18 is clamped between the dish 12 and the lid 14 and held in place by an annular plastic retaining ring 20. The filter material 18 divides the vessel 16 into two chambers: an inlet chamber 22 in which the embryos and a desired amount of solution are retained, and an outlet chamber 24 from which the excess solution escapes from the vessel 16.
The dish 12 is substantially transparent and has a planar circular bottom 26. A cylindrcal sidewall 28 extends upwardly from the planar bottom 26. Grid markings 30 are formed in the dish bottom 26 which are visible under a microscope and which facilitate extraction if embryos from the dish 12. The grid markings 30 divide the dish bottom 26 into a number of linear regions, as shown in Fig. 1. Alternatively, the grid markings may define quadrant sectors as shown in Fig. 8, or may comprise any grid pattern.
An inlet tube 32 penetrates the dish sidewall 28. The inlet tube 32 discharges into the inlet chamber 22 of the vessel 16 through a fluid inlet opening 34. In the preferred embodiment the inlet tube 32 is integrally formed with the dish sidewall 28 and projects outwardly from the sidewall. The inlet tube is preferably angled from the bottom of the dish.
Flexible tubing 36 connects the inlet tube 32 to a balloon catheter flushing device 38 described more fully below.
The lid 14 has a circular top 40 and a cylindrical downwardly extending sidewall 42 which generally defines the outlet chamber 24. A lip 44 projects outwardly from the top 40 perpendicular to the sidewall 42. The lip 44 is somewhat thicker than the top 40.
Indicia 46, for example in the shape of an arrow, are incorporated onto the exterior of the lip top 44. The indicia 46 cooperate with graduated markings 48 on the dish sidewall 28 to aid in setting the volume of liquid retained within the vessel 16 as described more fully below. Alternatively a protruding outlet tube 50 may substitute for the lid indicia to gauge vessel retained volume.
The outlet tube 50 extends through the lid sidewall 42 out of the lid and directs flushing fluid out of the collector 10. The outlet tube 50 had cylindrical walls preferably integrally formed with the lid 14. The outlet tube 50 communicates with an outlet opening 52 within the lid, which is spaced a sufficient distance from the lid sidewall 42 to ensure proper fluid retention within the vessel 16 to ensure hydration of the collected embryos. In the preferred embodiment the outlet tube is a rigid plastic part formed integrally with the lip top 40 and the outlet opening 52 is an aperture formed in the tube and spaced from the lid sidewall 42. The outlet tube 50 is adapted to snugly receive a length of flexible tubing 54 which drains away excess solution.
The filter material 18 is circular, and is sufficiently larger in diameter than the lid sidewall to effectively cover the opening in the lid defined by the lid sidewall 42. The pore-size of the filter material 18 is sufficient to prevent an embryo from passing through the filter while allowing the solution, i.e. flushing fluids and other biological substances ot pass through. For example, a 40 µm filter pore size may be used for the collection of cattle embryos.
The filter material 18 is clamped against the lid 14 by the retention fitting or retaining ring 20. The retaining ring 20 is preferably a molded plastic part which has a ring sidewall 58 which engages the filter material between the ring sidewall and the lid sidewall 42. A flange 60 projects outwardly from the ring above the sidewall 58. In assembling the collector 10 the ring 20 is fit over the filter material 18 which is laid over the lid sidewall and pressed into place such that the retaining ring flange 60 abuts the lid lip 44 forming a fluid tight seal between the lid, filter and the ring. The inner diameter of the ring 20 is only slightly greater than the outer diameter of the lid sidewall 42 such that the filter material 18 holds the ring engaged with the lid 14 in a friction fit. The height of the ring sidewall 58 is less than the height of the lid sidewall 42 such that an axially extending portion 62 of the filter material is exposed beneath the reaining ring 20. This portion 62 engages with the dish sidewall 28 to hold the dish together with the lid 14 in a tight but releasable friction fit. The dish 12 is thus engaged with the lid 14 in a fluid tight seal.
The lid 14 and dish 12, although firmly connected, are rotatably positionable. Thus, if desired, the volume of fluid retained within the vessel 16 may be adjusted by changing the vertical separation between the inlet opening 34 and the outlet opening 52. The indicia 46 and base markings 48 facilitate setting the volume at a desired level. As shown in Fig.s 3, 4 and 5, the smallest volume of fluid contained in the device will occur when the outlet opening is positioned at 180 degrees from the inlet opening. The maximum volume will occur when the outlet opening is positioned at 0 degrees from the inlet opening. The fluid outlet opening 52, because it is spaced radially inwardly from the lid sidewall, when rotated tracks in a concentric circle with a smaller circumference than the circumference of the dish. This circle provides the variable volume feature of the device. The other factor in the volume determination is the spacing of the fluid inlet opening from the sidewall.
For such embryo collection and transport devices of the present invention, that do not have cylindrical walled dishes and lids, the dish may be provided with a plurality of outlet tubes, each having an outlet opening within the dish which is spaced a greater distance from the sidewall. The select the amount of liquid retained with this device, a user would plug the outlets not used and connect the flexible outlet tubing to the outlet tube having an opening at the desired level.
Although the collector 10 will preferably be supplied with the filter material in place, it may be supplied unassembled so that the end user may utilize filter material suited to a particular application.
An exemplary dish is approximately 8 cm in diameter and approximately 2 cm tall. The entire device of the collector 10 is approximately 3 1/2 cm high by 8 cm, providing a total volume of approximately 180 milliliters. The device may be fabricated of disposable plastic, or alternatively be be molded of materials which are sterilizable and which do not produce chemicals which harm embryos. The device 10 may be made entirely of transparent material to facilitate inspection of the interior. The dish bottom is transparent in order to permit direct use under the stereomicroscope.
When it is desired to collect embryos from a subject animal, as shown in Fig. 2, the flexible inlet tubing 36 is connected to the balloon catheter flushing device 38 which has been inserted in a conventional manner into the uterus of the animal, such as a cow or a horse. Conventional embryo flushing techniques are then performed. A flushing fluid of sterile solution is released from an elevated reservoir 64 and is introduced through the flushing device 38 into the animal's uterus. The uterus is washed with a quantity of fluid sufficient to suspend the embryos. Typically one to two liters (1) of the flushing solution are used to flush a cow's uterus. The cow's uterus holds no more than 50 to 60 milliliters (ml) of fluid. In a process which may last thirty to sixty minutes, small quantities of flushing fluid are repeatedly introduced into the animal's uterus. Once the uterus is filled, a first clamp 66 or valve in the supply line of the fluid from the reservoir 64 is closed and a second clamp 68 or valve in the inlet tubing 36 is opened to alow the flushing fluid and any suspended embryos to discharge from the uterus into the filtration vessel 16 of the collector 10.
As best shown in Fig. 5, the device 10 is suspended from the flexible inlet tubing 36 in a generally vertical orientation. Fluid enters the vessel 16 through the inlet opening 34 and flows across the filter material 18 from the inlet chamber 22 to the outlet chamber 24 and thence through the outlet tube 50 into the outlet flexible tubing 54 which discharges the waste fluid into a waste receptacle such as a bucket 70. Mammalian embryos 72, which are too large to pass through the filter material 18, are retained within the inlet chamber 22.
The generally vertical orientation of the filter material 18 has several beneficial effects. First, the flow of liquid across the filter material is generally horizontal, and thus not beneath the total level of fluid contained within the vessel, subjecting the suspended embryos to reduced pressure levels. Secondly, as the flow through the collector 10 is intermittent as a result of the repeated filling and flushing of the animal's uterus, the flow into the vessel will at times be intense, and at other times relaxed. The vertical filter orientation presents a greater surface area of filter material to the liquid as the volume of liquid within the vessel increases. This greater surface area which is presented as the fluid level ascends results in a reduced fluid flow rate across the filter and again reduced forces exerted on the fragile embryos. Furthermore, the denser mucus will tend to sink towards the dish sidewall, not onto the filter.
The vertical orientation of the filter in use also has protectice benefits to the embryos being collected. Should the collector 10 be jarred, tilted or displaced so as to tip the vessel and elevate the outlet opening above the inlet opening, at worst a greater quantity of flushing fluid than desired will be temporarily retained within the vessel. At no time will the embryos be left without sufficient liquid to support them and prevent their desiccation and death. In any event, at the time of completion of the collection the collector 10 may be returned to its proper orientation without damage to the collected specimens.
When the device 10 is disassembled for extraction of embryos, the retaining ring will hold the filter material in place over the lid, allowing embryos which may have become attached to the filter to be flushed off the filter, either by flowing liquid in through the outlet tube, or by simply applying water to the exposed filter material.
As all the waste fluid is discharged through the outlet tubing 54 at a location remote from the collector 10, the exterior thereof and the surrounding area remain unsoiled by the flushing solution. This feature of the collector 10 permits the device to be placed close to the warmth of an operator's body during the collection process, for example within a pocket beneath a jacket or coat. In this way the embryos may be protected against debilitating cold during collection.
After the collection procedure has been completed, the inlet and outlet flexible lengths of tubing are clamped or tied off and the fluid tight assembly is transferred to a laboratory for extraction of the collected embryos. When the dish is placed on a horizontal surface, as shown in Fig. 6, all the solution and embryos within the vessel 16 will collect within the dish 12. The outlet opening 52 is spaced sufficiently from the lid sidewall 42 that enough solution is retained within the dish to sufficiently wet the collected embryos and prevent dehydration and death of the embryos. However, it is important that an excessive amount of liquid may not be retained, for in that case the fluid level would exceed the height of the dish sidewall 28 and would overflow from the dish when the lid 14 is removed. The volume retained within the vessel is also best set at a low level to make extraction of embryos less difficult. Once in the laboratory the lid 14 and the filter material 18 are removed from the dish 12. If material is clinging to the filter material, sterile fluid may be injected into the lid 14 through the outlet tube 50 and any embryos which remain attached to the filter material may be backwashed into a separate petri dish for later examination and extraction. As best shown in Fig. 7, the dish 12 is placed on the stage of a stereomicroscope beneath the objective 74 thereof. A selection probe or pipette 76 may then be used to extract and package for shipment thos embryos identified through the stereomicroscope.
An alternative reusable embryo collector 110, shown in Fig. 8, has a lid 112, a resilient O-ring 113, a filter 114, an O-ring gland 115, and a retaining ring 116 which engage in a friction fit with a stainless steel or heat resistant plastic sleeve 117. The O-ring 113 fits within a gland in the sleeve and releasably engages with a conventional petri dish 118. The retaining ring 116 has ring sidewalls 119.
The lid 112 has a circular top 120 with a cylindrical sidewall 122 extending perpendicularly off from the top 120 and surrounding a lid cavity 124 containing a c-shaped channel 125. A lid lip 126 projects outwardly from the lid top 120 approximately perpendicular to the lid sidewalls 122.
The lid sidewall 122 has an opening 127 communicating with the lid cavity 124 defined by the sidewalls 122 and the lip top 120. The c-shaped channel 125 is formed within the lid cavity on the underside of the lid top 120 and runs from the lid sidewall opening 127 across a substantial portion of the lid width. The cylindrical sleeve 117 has portions defining an inlet tube 128 which extends into the sleeve. The sleeve inlet tube directs flushing fluid containing embryos into the sleeve interior. A flexible inlet tube 129 is connected to the inlet tube 128 to conduct fluid from the balloon catheter. The O-ring gland 115 is an internal groove formed on the interior surface of the sleeve 117. A resilient O-ring 113 is positioned within the O-ring gland 115 to releasably engage a conventional laboratory container such as the disposable petri dish 118 in a fluid tight seal. The O-ring 117 is seated in a position spaced from the ends of the sleeve. A rigid outlet tube 130 is inserted through the opening 127 and is slidable within the channel 125 to position an outlet opening 132 of the outlet tube 130 at a desired position within the lid 112. An O-ring 134 is positioned in a gland 136 within the lid sidewall opening 127 to form a liquid tight seal with the outlet tube 130. A flexible outlet tubing 138 is connected to the outlet tube 130 to direct waste fluid to an appropriate receptacle. It should be noted that the lid 112 and positionable outlet tube may also be employed with the collector 10 if desired.
The filter 114 is of a circumference sufficient to cover the lid top 120 and the lid sidewall 122 and is positioned across the lid cavity 124. The filter 114 has a pore size sufficient to prevent an embryo from passing through the filter while allowing flushing fluids and mucus to pass through. The retaining ring 116 fits over the lid sidewall 122 with the filter 114 therebetween.
For convenience the collector 110 may be used, sterilized and reused with a new petri dish. It may then be economically used with a variety of readily available petri dishes of different capacities and designs.
A second alternative embodiment of the embryo collector of the present invention is shown in Fig. 9. The collector 140 has a transparent dish 142 having a base and an upwardly extending sidewall 144 through which an inlet tube 145 discharges. An annular plastic sleeve 146 connects the dish 142 to a id 148 having a fluid outlet tube 150. The lid has a cylindrical sidewall 152. The inner diameter of the sleeve 146 is sufficient to provide an interference fit with the dish 142. A filter material sheet 154 is clamped between the lid 148 and the sleeve 146. A liquid impervious barrier 156 is integrally formed with the sleeve 146 and blocks the passage of liquid between the dish 142 and the lid 148 except through a segment shaped opening 158 defined within a sleeve sidewall 160 and above the barrier 156. The level of the opening 158 determines the amount of liquid which will be retained within the collector 140. Rotation of the sleeve 146 may thus control the desired level of retained liquid.
The collector 140 is employed in a manner generally similar to the collector 10. It can be produced at low cost as the dish 142 and lid 148 may be formed as identical pieces utilizing the same molds.
To securely engage the sleeve 146 with both the lid and the dish, the interior diameter of the sleeve may be formed somewhat larger on the side which mates with the dish. Alternatively a constant internal diameter sleeve may be provided with a second filter sheet between the sleeve and the dish.
A fourth embodiment of the embryo collector of the present invention is shown in Fig. 10. The collector 162 has the dish 142 and the lid 148 identical to those of Fig. 8. The dish and lid are joined by a sleeve 164 which is a simple annulus which may be conveniently and economically formed such as by extrusion. A fluid impervious flexible sheet barrier 166 is engaged between the lid 148 and the sleeve 164 in a liquid tight friction fit. The barrier 166 has holes 168 punched or die cut therein for the flow of fluid therethrough. A filter material sheet 170 is engaged in a friction fit between the dish 142 and the sleeve 164. The orientation of the holes 168 in the barrier sheet 166 will determine the liquid level retained within the device 162.
In certain applications it may be desirable to provide the embryo collection and transport device of the present invention with two or more filters to prevent mucus and other larger particles plugging or clogging the small pore filter. A collector 172 shown in Fig. 11 has a reusable lid 174 and a sleeve 176 for use with a disposable petri dish 188. A retaining ring 200 fits over a small pore filter 202 and the lid 174 to stretch the filter over the lid. The sleeve 176 fits over the retaining ring 200 and clamps a coarse filter 204 therebetween. The sleeve is sized to engage with the petri dish 188 in a friction fit. The coarse filter 204 is formed of a sheet of filter material which permits the passage of particles which are larger than those permitted to pass through the small pore filter 202.
Another embodiment of the embryo collector, employed to separate out a portion of the mucus retained in the collector, is shown in Fig.s 12 to 15. A collector 300 has a small pore filter 302 through which embryos may not pass and a large pore filter 304 which is sized to prevent the passage of mucus therethrough. The collector 300, as best shown in Fig. 12 has a transparent dish 306 with an upwardly extending sidewall 307 through which an inlet tube 308 extends. The large pore filter 304 is placed over the dish sidewall 307, and a first retaining ring 310 is pressed over the filter to hold it in place. In a similar manner the small pore filter 302 is held in place over the sidewall 312 of a lid 314 by a second retaining ring 316.
A transparent plastic sleeve 318 fits over the filter covered sidewalls 307, 312 of the dish 306 and lid 314. The sleeve 318 serves to connect dish and the lid while separating the large pore filter from the small pore filter as shown in Fig. 15. However, as shown in Fig. 13, the sleeve also serves as a second collection and examination dish.
The sleeve 318 has a cylindrical sidewall 320 with an impervious plastic barrier 322 which extends within the sidewall 320 to a desired height, preferably greater than one half the height of the sleeve 318. The barrier 322 has a lip 324 which extends perpendicular to the barrier towards the lid 314, said lid including an outlet tub 126. The barrier 322, the lip 324 and the sleeve sidewall 320 define a compartment 328.
As shown in Fig. 15, during collection fluid containing embryos and mucus flows into the dish 306. Fluid containing embryos flows across the large pore filter 304 into the sleeve 318, and mucus is retained within the dish 306. The embryo containing fluid flows over the barrier lip 324, through the small pore filter 302, into the lid 314 and out of the collector through the outlet tube 326.
Once collection has been completed the inlet and outlet tubes are sealed. While still in its vertical orientation the collector 300 divides its contents into three regions: fluid, mucus and perhaps embryos remain within the dish 306; fluid and embryos remain within the sleeve 318, and fluid only remains within the lid 314.
As shown in Fig.s 13 and 14, after collection the collector 300 is tilted by 90 degrees and placed so that the dish 306 rests on a horizontal surface. First the lid 314 and the attached small pore filter and ring 310 are removed from the sleeve 318. Any embryos remaining on the small pore filter may be flushed into a separate petri dish if desired. At this point liquid will have collected both within the compartment 328 and also in the dish 306. The fluid contained within the compartment 328 will be free of mucus and will be easily examined for extraction fo embryos. The fluid within the dish 306 will contain mucus, and may contain some embryos also. It may be handled in the way described above with respect to the collector 10.
The cleanliness of the collector 10, 110, 140, 162, 172 or 300 may further be protected in the unsanitary conditions of most collection sites by packaging the device in plastic shrinkwrap or a thermoformed clam shell package 406, shown in Fig.s 16 and 17, with only the inlet flexible tubing and the outlet flexible tubing extending from the package. The thermoformed package has a base 408 attached by an integral hinge 410 to a cover 412. The packaging serves to prevent dust, soil, animal wastes and other debris from accumulating on the dish during collection and hence preserves the optical clarity of the dish under microscopic inspection. The shrinkwrap may be of an opaque plastic to protect the collector's contents from exposure to damaging ultraviolet light.
As shown in Fig. 16, the user may employ a specialized garment 413 with an exterior pocket 414 with an upwardly opening flap 416 which allows the collector to be inserted into to pocket. The pocket will preferably have a lower exit hole 418 for the passage of the flexible outlet tubing. The garment 413 preferably has an inner layer adjacent the wearer's body that is relatively thin and conductive to heat transfer, and an outer layer 420 which is thermally insulated to retain the heat of the wearer's body and to thus warm the contents of the device.
The lids, rings, and sleeves of the device may be made of autoclavable or sterilizable material such as glass, metal such as stainless steel, or heat resistant plastics. The dish may be made of glass or transparent plastic. The collector may be formed in which the filter material is fixedly connected to the lid such as by welding or adhesive attachment. Such an embodiment of the invention would not require a retaining ring to hold the material in place. Further the dish and lid of the present invention may be formed of any desired mating shapes other than the cylindrical shapes disclosed above. Such shape may be any desired regular polygon to permit adjustment of position of inlet and outlet openings in incremental steps.
Where embryos have been referred to herein, other biological reproductive products are also meant to be included, in particular unfertilized ova. The various embodiments of the invention disclosed above may, with substitution of appropriate filter material to accommodate the sizes of biological product to be obtained, be used for collecting of these other products.

Claims

A device for filtering sensitive biological micro-entities suspended in a flushing solution from this flushing solution, the device (10) comprising a housing which includes an inlet chamber (22) and an outlet chamber (24), separated by a sheet of filter material (18) which allows the passage of the flushing solution but retains the biological micro-entities (72), an inlet tube (32) extending into the input chamber and an outlet tube (50) extending out of the outlet chamber, characterized in that in the device (10) which is designed for an operating position wherein the filter material (18) is vertically oriented, in the outlet chamber (24) there is an overflow threshold (50, 52) between this chamber and the outlet tube (50).
Device according to claim 1, characterized in that the overflow threshold is constituted by a mouth opening (52) of the the outlet tube (50), said mouth opening being positioned at a vertical distance from the bottom level of the outlet chamber (24) in the operating position of the device (10).
Device according to claim 2, characterized in that the inlet chamber (22) and the outlet chamber (24) are confined by coaxial cylindrical structures (12, 14) coupled to each other so as to be mutually angularly adjustable.
Device according to any of claims 1 to 3, characterized in that it consists of a dish (12) made of a transparent material and having a base plate (26) and a perpendicularly extending dish sidewall (28), and of a lid (14) also having a base plate (40) and a perpendicularly extending sidewall (42), wherein the lid is engageable with the dish to form a fluid tight compartment, the dish confining the inlet chamber (22) and the lid confining the outlet chamber (24).
Device according to claim 4, characterized in that the filter material (18) extends over the open end face of the dish and/or or the lid.
Device according to claim 4 or 5, characterized in that the filter material (18) is clamped between the dish and the lid.
Device according to any of cliams 4 to 6, characterized in that the inlet chamber is confined by a petri dish (118) and a sleeve (117) extending the side walls of the petri dish, the inlet tube (128) extending into said sleeve (117).
Device according to any of claims 1 to 7, characterized by a second sheet of filter material (204) which is serially arranged upstream of the first mentioned filter material (202) and permits the passage of particles therethrough larger than those permitted to pass through the first mentioned sheet of filter material (202).
Device according to claim 4, characterized in that a sleeve (146) extends between the lid (148) and the dish (143), clamping the sheet of filter material (154) to the lid and joining the lid to the dish, wherein the sleeve (146) has portions defining a liquid impervious barrier (156) which blocks fluid flow from the dish to the lid beneath the level of the barrier.
Device according to claim 9, characterized by:
a) a large pore filter (304) clamped between the sleeve (318) and the dish (306), the large pore filter having a pore size large enough for the passage of embryos there- through;

b) a lip (324) formed within the sleeve (318) and extended towards the lid (314) in a direction generally perpendicular to the barrier (322) which extends from the sleeve sidewall (312), such that the sleeve sidewall, the barrier and the lip define a compartment (328) for retaining fluid therein which has passed through the large pore filter (304).
Device according to claim 4, characterized in that a sleeve (164) extends between the lid (148) and the dish (142) and joins the lid to the dish; a sheet of liquid impervious barrier material (166) is clamped between the sleeve (164) and the lid (148), wherein the barrier material has portions defining openings (168) for the flow of fluid through the barrier material sheet, the openings being disposed at the overflow level; and that the sleeve (164) clamps the filter material 170) sheet to the dish (143).