EP1356020A1

EP1356020A1 - Microbiological security stations useful for medically-assisted reproduction

Info

Publication number: EP1356020A1
Application number: EP02701341A
Authority: EP
Inventors: Catherine Poirot
Original assignee: Universite Pierre et Marie Curie Paris 6
Current assignee: Universite Pierre et Marie Curie Paris 6
Priority date: 2001-01-30
Filing date: 2002-01-29
Publication date: 2003-10-29
Also published as: US20040202584A1; JP2004527234A; FR2820144A1; FR2820144B1; WO2002061031A1; CA2436635A1

Abstract

The invention concerns the field of microbiological security stations for manipulating microscopic samples under visual control. More particularly, the invention concerns microbiological security stations adapted to the handling of biological organisms, and particularly for in vitro fertilization, without being exclusive to that particular field of application. The inventive microbiological security station is essentially characterised in that there is incorporated in the body of the station an optical system enabling to observe a sample placed in the chamber, so as to clear to a maximum the workspace, but also so as to make it possible to clean rapidly and completely the internal volume of the chamber.

Description

MICROBIOLOGICAL SAFETY STATIONS FOR USE IN MEDICAL PROCEDURE ASSISTANCE

The invention relates to the field of microbiological safety stations (hereinafter designated by the acronym PSM), allowing the manipulation of microscopic samples under visual control. The invention relates more particularly to PSMs suitable for the manipulation of biological material, and in particular for in vitro fertilization (IVF), without however being limited to this field of application.

The handling of biological material most often requires means of protecting the samples handled and / or the manipulator against microbiological risks. These manipulations are therefore generally carried out in laminar flow hoods of the horizontal or vertical type.

Horizontal laminar flow hoods are enclosures where the air comes from the rear part of the hood and flows horizontally towards the front part of the hood, which is widely or even entirely open. The manipulator is placed in front of this open part, and is therefore exposed to projections coming from the sample which it is handling and / or treating. In this configuration, the manipulator is therefore not protected from possible contamination.

The manipulator is protected in microbiological safety stations (PSM), the simplest model of which (PSM type I) has an air flow entering the hood and a filtration system for the exhaust air. On the other hand, the samples handled in type I PSMs are not protected. In vertical laminar flow hoods, the flow comes from the ceiling of the hood and descends towards the worktop. On the front part of these hoods there is a protective glass to avoid projections out of it. These hoods therefore constitute microbiological safety stations, since they protect the manipulator. Vertical laminar flow hoods belong to the category of type II PSM, defined in that they ensure the protection of the sample, the manipulator and also the environment, when they are equipped with a filtration system of the expelled air.

Certain types of microbiological manipulations require an enlarged observation of the sample handled, and therefore the use of a binocular magnifier or a microscope. The introduction of such an optical device into a laminar flow hood disrupts the flow, and therefore reduces the efficiency of the hood. Using a binocular magnifier or microscope under a vertical flow hood is particularly difficult (if not impossible), due to. the protective glass located on the front of the hood. In addition, the introduction of material into the working space of a hood impairs the ease of cleaning said working space and contributes to increasing the risks of contamination between different samples handled.

The PSM and horizontal laminar flow hoods currently available therefore do not allow biological samples to be manipulated under visual control through a magnifying optical device, under conditions ensuring microbiological safety of the sample and of the manipulator and, moreover, allowing easy cleaning. manipulation space.

The object of the present invention is to solve at least part of the aforementioned drawbacks. The present invention relates to a microbiological safety station (PSM), comprising walls defining a workspace, and in which an optical device is provided placed outside the workspace, and allowing observation of a sample in at least one area of the work space by a transparent window secured to one of said walls.

In a particular embodiment of the invention, the PSM comprises a plate P suitable for receiving the sample in the observation area of the working space, the plate comprising a transparent window F1 allowing the lighting and / or the observation of the sample.

In addition, the floor of the workspace of a PSM according to the invention may include one or more zones equipped with temperature regulation means so as to be thermostatically controlled at a temperature between 20 and 45 ° C, and in particular at 37 ° C +/- 0.2 ° C. In particular, the plate P mentioned above can be equipped with such a temperature control device.

In the PSMs of the invention, the optical observation device preferably comprises lighting means suitable for illuminating the sample in the observation area, and light collection means allowing the observation of a sample in this observation area. All these means can be located under the floor of the working space, so as to illuminate and observe the sample from below, through the window F1 of the stage. Alternatively, all or part of the lighting and / or light collection means may be located behind one or more other windows provided in at least one of the walls, for example in the upper wall (ceiling), placed opposite the floor. The light collection device of the PSM of the invention preferably comprises an autofocus camera. In order to observe microscopic samples, this camera is preferably arranged to ensure several magnifications of the image between 10 and 1000, in particular between 10 and 400, and if necessary, only between 10 and 70.

In a preferred embodiment of the PSM of the invention, the optical light collection device (for example, the autofocus camera) further comprises fine-tuning means at each magnification, which can advantageously be controlled from a dashboard located outside the workspace and / or integral with one of the walls defining the workspace. For example, this dashboard can be located on the front face, outside the hood, or in the form of buttons or touch-sensitive keys formed on a screen, incorporated into the floor of the hood, for example on the left. from the work and observation station.

The light collection device of the PSM of the invention is preferably connected to a device for recording the collected images, such as for example a computer equipped with data storage means, such as a hard disk or a medium. removable recording.

In a preferred embodiment, the PSM of the invention may include an observation screen E, integral with one of the walls defining the working space, said screen allowing the operator to view the images collected by the light collection. This observation screen can be, for example, a flat screen integrated into the rear wall of the workspace.

In a particular embodiment of the invention, the PSM may further include a zone for gassing the samples, comprising a gas inlet, an enclosure allowing the confinement of the gas, and a connection device. connecting the gas supply to the enclosure. Preferably, the enclosure and the connection device are easily removable, and more preferably, the enclosure and the connection device are inserts of consumable type. In this embodiment of the invention, the gas inlet is preferably integrated into one of the vertical walls defining the working space, and the enclosure is a transparent bell, connected to the gas inlet by a pipe. The connection device connecting the gas inlet to the enclosure can advantageously include a protective flange intended to protect the gas inlet from projections.

According to another embodiment, the PSM of the invention comprises a data entry device. This input device can consist of a tactile keyboard secured to the floor of the hood and connected to a computer. Alternatively, the touch keyboard can be located outside the workspace, on the front of the hood. If necessary, a data sheet being entered can be viewed on screen E mentioned above, or on a portion of this screen. Alternatively, a second specific screen can be integrated into a wall of the workspace.

The floor and the vertical walls defining the workspace of a PSM according to the invention are preferably flat and made of smooth, washable materials and resistant to cleaning products used in laboratories, such as products containing quaternary ammoniums or the most powerful virucides. Alternatively and / or additionally, the floor consists of one or more removable disposable elements or sterilizable by autoclave.

Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

FIG. 1 is a very schematic perspective view of a microbiological safety station (PSM) according to the invention, FIG. 2 schematically details part of the optical device of the PSM in FIG. 1, and

- Figure 3 shows an exemplary embodiment of the data entry keyboard.

The object of the present invention is a PSM (as defined in the introduction) comprising several elements cooperating in an original way to allow easy manipulation and under visual control, of microscopic objects, under conditions ensuring the protection of the objects handled and the manipulator vis-à-vis microbiological risks. This invention can be used for all types of applications requiring microbiological protection of the objects handled and / or of the manipulator. Examples include the making of small sterile equipment, research in biology or cell therapy (for example, for the preparation of corneas intended to be grafted), and the manipulation of embryos or stem cells. A preferred field of application of this invention is in vitro fertilization.

Medically assisted procreation (MPA) techniques are concerned with the conception of human beings. They are also applied in the veterinary field.

The purpose of In Vitro Fertilization (IVF) is to ensure the meeting between the oocyte (female gamete) and the spermatozoon (male gamete) outside the body (in vitro).

The different biological stages of IVF are spread over several days (Ji): > at OJ • preparation of spermatozoa

• search for oocytes in follicular fluids contained in syringes

• culture of oocytes

• insemination: putting in contact in the culture dishes of the spermatozoa with the oocytes.

> on D1 the oocytes are rid, one by one, of their surrounding cells (decoronization), to allow microscopic examination of the signs of fertilization (presence of the pronoyals).

> on D2 or D3 ^" observation of the first stages of embryonic development

• replacement of part of the embryos in the patient's uterine cavity using a small catheter.

Great rigor must accompany these operations, particularly in the area of health security. Manipulators must in fact avoid contamination of the gametes entrusted to them, ensure sterile embryonic culture from an infectious point of view, and avoid cross-contamination between samples.

To achieve these objectives, the various stages of in vitro fertilization procedures are carried out in a sterile manner, conventionally in a laminar flow hood. The purpose of the laminar flow of the hoods is to prevent the introduction of potentially contaminating foreign elements into the work area. For optimum efficiency, the handling area must be free of objects disturbing the flow. However, the search for oocytes (150 μm in diameter), insemination, decoronization and loading of the transfer catheter can only be carried out under visual control, currently carried out using a binocular magnifier.

Consequently, for all stages of IVF, except for the preparation of sperm, which does not require microscopic control, practitioners need to place a binocular magnifying glass under a hood, in order to work under conditions of correct asepsis. Unfortunately, as explained above, the use of a binocular magnifier is incompatible with the use of a vertical laminar flow hood. In practice, the stages requiring microscopic visual control are carried out by placing a binocular magnifier under a hood with horizontal flow, which poses three types of problem: first, the manipulator is not protected; second, the flow is disrupted, which decreases efficiency. of the hood and therefore the degree of protection of the sample; third, cleaning the hood (and binocular magnifier) after handling a sample is long and difficult.

In IVF, the manipulator needs to be protected for at least three reasons:

^» Any sample of human origin should be considered a priori as at risk of infection;

^• There are gestures at risk of contamination, such as the possible projection of biological fluids during the examination of follicular fluids, liquids which are quite often bloody; • Finally, certain legislations tend to exclude patients suffering from certain diseases from the protocols of medically assisted procreation. For example, in France, the Bioethics law of July 24, 1994 obliges practitioners to control the HIV serology, hepatitis B and C and syphilis of all patients who must benefit from an AMP. Infected patients are no longer treated.

The pressure from couples in which at least one of the people is infected with one of the viruses referred to above (hepatitis B, hepatitis C, HIV, syphilis) has become such that research protocols for the management of patients infected fell into place. In some hospitals, such as at Cochin Hospital (Paris, France), couples who are serodifferent for the AIDS virus are supported, within the framework of a protocol financed by the ANRS (National Association for Research against AIDS). This management concerns couples where the patient is HIV-positive and the patient is HIV-negative. Couples where the patient is HIV positive are not supported because of the risk of contamination of the manipulators linked to the fact that said manipulators work under a hood with horizontal laminar flow for the stages of manipulation of female gametes. In addition, some MPA laboratories do not treat couples infected with the hepatitis C virus, for the same reasons.

To be able to respond to these requests and to protect the manipulator, it is therefore essential to work, for all stages of the MPAs, in microbiological safety stations (PSM), for example under hoods with vertical laminar flow.

In addition, the care of patients infected with a dangerous virus implies that the workspace in which the samples are handled, is systematically and perfectly sterilized after the treatment of each sample. Indeed, it is absolutely necessary to avoid contamination nosocomiales between the patients treated in the MPA protocols. Such contamination has been described (Lesourd et al., Human Reproduction, 2000, Vol.15 n ° 5, pp 1083-1085), emphasizing the attention that should be paid to this problem.

This type of nosocomial contamination can come mainly from two origins:

• First, inter-sample contamination can come from the manipulator (following a projection of a contaminated sample on his lab coat, for example), or from objects used by the manipulator, such as pencils or observation book.

• The second possible cause of inter-sample contamination is imperfect cleaning of the hood and its contents. The risk of contamination by the hood and the instruments used under the hood is all the higher as the workspace is cluttered with many objects, and that these objects are of complex geometry. Thus, a binocular magnifier, comprising in particular a plate, several objectives, lamps and adjustment knobs, is a particularly long and difficult instrument to clean so as to ensure its sterility.

In practice, if the complete cleaning of the hood requires a long time, incompatible with the constraints linked to the number of samples to be processed each day on a station, this cleaning will be carried out imperfectly. The obstruction of the workspace by objects necessary for handling is therefore troublesome for two reasons: on the one hand, it affects the efficiency of the hood by disturbing the laminar flows, and on the other hand, it makes sterilization of the hood is long and difficult, and in practice often imperfect. In this context, there is therefore a significant need for a microbiological safety station adapted to the needs of IVF, that is to say ensuring the simultaneous protection of the sample, the manipulator and the environment, and allowing microscopic observation of gametes and embryos, while reducing the risk of cross-contamination. The constraints linked to the nature of the manipulations in IVF are found in the manipulations of other biological samples, in particular the manipulations involving human or animal cells for research, cell therapy, gene therapy, or research on embryos. A safety post adapted to IVF is therefore suitable for the other operations mentioned above. Ideally, such a PSM will be easy and quick to clean and will not require the introduction under the hood of material other than consumable material or if necessary sterilizable by autoclave.

The PSM of the invention makes it possible to respond to at least some of these constraints. Indeed, an essential and original point of the PSM of the invention is the integration, in the body of the PSM, of all the material necessary for in vitro fertilization, and in particular of the optical system, in order to strip the space as much as possible. work to obtain a good level of protection for the sample and the manipulator, but also so that the interior of the hood is quickly and completely cleanable between each sample, thus reducing the risk of contamination between samples.

The PSM of the invention can be a type I, II, or even III PSM. Type III PSMs are enclosures in a confined atmosphere maintained under pressure, in which the manipulations are carried out by means of gloves sealed at the enclosure. The integration of optical equipment in the body of such

PSM is part of the present invention. In general, the integration of optical equipment into the body of any microbiological safety station, so as to obtain the most open workspace possible, is part of the invention. Preferably, the PSM is of type II, for example a vertical laminar flow hood.

In a preferred embodiment of the PSM of the invention, illustrated in FIG. 1, the working space is defined by the floor 1 of the hood, vertical side walls 2, the bottom 3 of the hood, its ceiling 4, and a front protective pane 5. It further comprises a plate 6 suitable for receiving the sample in an observation area of the working space, said plate comprising a first transparent window 7 allowing lighting and / or observation of said sample.

In this embodiment of the invention, the optical observation device comprises lighting means 8 suitable for illuminating the sample in the observation area, and light collection means 9 allowing the observation of a sample placed in this area.

The optical device is preferably a video system making it possible to store images, for example an autofocus camera 9 connected to an image recording device, such as a computer 17 equipped with data storage means 18. The cameras can be digital or analog. Preferably, the video system essentially comprises an optical unit 9 for the collection of photons from the observation area and a system for controlling the various adjustments, for the focal length, the lighting 8 and the magnification. This optical unit can be reversed to allow fixing under the worktop 1 (hood floor). The majority of technical gestures are made at relatively low magnifications (from 10 to 70 approximately). However, a more efficient optical system allowing magnifications up to 400 or more can be used to observe the zygotes on D + 1 and the embryos, on D + 2 or D + 3, or even until D + 6.

For this purpose, a ¹ / z inch CDD sorting camera can be used to observe on a 1 1 17 "(inch) screen, a 125 μm object with a size of approximately 100 mm.

Alternatively, other types of image collection devices can be used. By way of example, but in a non-restrictive manner, mention may be made of the charge coupled device bars (better known by the acronym CCD).

The optical element 9 can be placed under the floor 1 of the hood, opposite a transparent window 7 preferably integrated in the plate 6, as shown in Figures 1 and 2. Also preferably, the plate 6 , located around this window 7, is a heating zone.

Other arrangements of the optical system can be envisaged. For example, at least part of the lighting and / or light collection means may be located behind one or more windows integral with at least one of the walls and distinct from the window 7. In particular, certain elements, in particular the light collection means can be placed at the level of the ceiling 4 of the hood, opposite the observation area.

In a particular embodiment of the invention, the entire observation area is illuminated by a device 8 called "long front", by adding a condenser placed about 182 mm from the sample. This system includes an optical fiber attached to the end of a stainless steel tube, which is itself integral with the wall of the workstation. The light generator, for example, has a power of 150 W, and it is preferably adjustable. Of course, any other lighting means known to those skilled in the art can be used to illuminate the area for handling and observing the sample.

In a particular embodiment of the invention, the control of the entire apparatus is carried out from a pedal set located on the ground under the work station, in order to direct the various adjustments by pressing on the pedals assigned to each of the functions. The motorization system comprises for example three pairs of pedals placed on an inclined support:

- 2 pedals for focusing

- 2 pedals for zooming - 2 pedals for lighting.

Of course, control systems other than the pedals can be envisaged. For example, the fine adjustment of the focus can be carried out by keys actuated by the fingers at the level of an instrument panel 10, placed on the front of the hood, to the left of the observation zone of the The sample, as shown in Figure 1. The zoom and lighting settings can also be made from this dashboard.

If necessary, a control unit, placed outside the hood, includes a device for adjusting the speed of the motorizations, for example a potentiometer (this adjustment should preferably be made before the operator puts his hands in the flux).

Preferably, the PSM of the invention comprises an observation screen 11 secured to one of the walls defining the workspace, said screen making it possible to view the images collected by the light collection device 9. From more preferably, the observation screen 1 1 is a flat screen secured to one of the vertical walls 2 or 3 of the hood, for example of the rear wall 3 of the workspace, behind the observation area of the sample.

In addition, there are other general requirements to ensure optimum quality of the IVF technique. First, the handling temperature must be maintained around 37 ° C, which implies a work plan thermostatically controlled at around 37 ° C. With this in mind, the floor 1 of the workspace may include one or more zones equipped with temperature regulation means, so as to be thermostatically controlled at a temperature between 20 and 45 ° C, in particular at 37 ° C +/- 0.2 ° C. In particular, the plate 6 can be equipped with such means for regulating its temperature. It may be, for example, heating resistors placed under the plate 6, and therefore outside the working space. If necessary, the entire floor of the workspace can be thermostatically controlled.

Another important constraint in the case of IVF is to maintain the pH of the culture media at around 7 - 7.2, so as not to alter the viability of the gametes and embryos. These cells do not tolerate Hepes type buffers well, the pH is maintained by the presence of bicarbonate in the culture media and a gassing system at 5% CO ₂ to balance these media. Between two manipulations on a sample, this sample is therefore preferably placed in an enclosure 13 maintained at approximately 5% CO ₂ . This enclosure 13 can for example consist of a bell connected to a gas inlet 12 by a tube 14. In order to reduce the risk of inter-sample contamination mentioned above, this bell can be replaced after treatment of the samples of each patient . For this purpose, one can consider either autoclavable bells (for example, glass), which must be systematically sterilized after use, or single-use bells, for example consumables made of fine plastic. The tube 14 is preferably for single use, but it can also be reusable after sterilization by autoclave or by any other means known to those skilled in the art.

One aspect of the invention relates to a protective collar 15, intended to protect the gas inlet 12 from possible projections of biological liquid or aerosols. Indeed, a gas supply inevitably constitutes a rupture of the plane of the wall in which it is integrated, and can therefore be difficult to clean. Tools and protocols to reduce the number of objects needed in the hood during the processing of each sample are also offered, always with the aim of limiting the risk of nosocomial contamination between samples and / or patients. Thus, a system for capturing observed data, intended to replace the current

"Bench sheet", can be integrated into the PSM. The recording of the data must be able to be done without passing by the intermediary of a traditional keyboard, which does not answer the health security rules. Several types of data entry means can be envisaged. A first possibility is to integrate a touch keyboard into the work plan of the hood

16, consisting of predefined keys. A second possibility consists in using a screen where predefined keys appear, on which one can direct a pointer. The screen is preferably secured to one of the walls of the PSM. It may for example be the observation screen (11) or an active window thereof. Alternatively, it can be a separate screen from

(1 1). The movements of the pointer and the activation of the keys can be carried out from a pointer control area, better known by the English terminology "track pad", or, more generally, by any means known by the name of "mouse ". Any other means known to those skilled in the art can also be used for entering the data relating to the samples treated.

These data entry means (touch screen, track pad or other) are, for example, located to the left of the optical system (unlike what is shown in Figure 1). A possibility of "deactivation" of the input means must be provided to avoid the entry of outliers when cleaning the worktop of the hood. A possible list of the predefined keys of a keyboard 16 is given below:

Day keys: D1 D2 D3 D4 D5 D6

Numbers Key for viewing the bench sheet Validation key Predefined keys:

oocyte

Empty skin cell Atretic oocyte

VG

M1

M2

OGP 1 GP

2GP

OPN

1 PN

2PN 3PN

Sup 3PN

Granular

vacuole

(Type) A (Type) B

(Type) C

(Type) D

morula

Compacted Morula Beginning of cavitation

blastocyst

Expanded blastocyst.

An example of the arrangement of the keys of such a keyboard is illustrated in FIG. 3. The data entry system can be linked to a computer station in the laboratory, from which the identity of the patients, associated with the samples to be processed, and the characteristics of the attempt are entered. The file of the couple to which the sample to be processed belongs, can be called up and displayed on the screen of the hood, for example via the number of the attempt. This number can include 6 digits (ex: 990123). The keyboard can therefore also contain numeric keys.

Two cases are to be considered:

1. the camera cannot observe the zygotes and the embryos 2. the camera makes it possible to observe the zygotes and the embryos.

In the first case, data recording is done on a single day.

When the manipulator presses a predefined key on the keyboard 16, the corresponding data is written on the bench sheet. A button for viewing the bench sheet allows it to appear on the screen

1 1 if necessary, if necessary in a predefined space on the screen.

In the second case, where the camera makes it possible to observe the zygotes and the embryos, day keys are necessary.

Data recording is done over several days (3 to 8 days).

It is therefore necessary to be able to recall the benchtop sheet of the corresponding couple to continue entering the data. For example, the number of the attempt allows the benchtop sheet to appear, the key corresponding to the day (ex: D1 or D2) allows data entry in the correct column. Numerical data can be entered in boxes on the bench sheet, such as the quotation for the survival of sperm at 24 hours. An example of a possible input keyboard is shown in Figure 3.

The walls 1, 2, 3, 4 and 5, defining the workspace, are preferably flat and made of smooth, washable materials resistant to cleaning products, such as products containing quaternary ammoniums or virucides more powerful. Alternatively and / or additionally, the floor consists of one or more removable and disposable or sterilizable elements by autoclave or by any other means.

Claims

1. microbiological safety station (PSM), comprising walls (1- 5) defining a workspace, characterized in that it comprises an optical device placed outside the workspace, and allowing observation of a sample in at least one area of the working space by a transparent window secured to one of said walls.

2. PSM according to claim 1, characterized in that it comprises a plate (6) suitable for receiving the sample in said observation area of the working space, said plate comprising a first transparent window (7) allowing lighting and / or observation of said sample.

3. PSM according to one of claims 1 or 2, characterized in that the floor (1) of the working space comprises one or more zones equipped with temperature regulation means, so as to be thermostatically controlled at a temperature between 20 and 45 ° C, in particular at 37 ° C ± 0.2 ° C.

4. PSM according to one of claims 2 and 3, characterized in that the plate (6) is equipped with temperature regulation means, making it possible to fix the temperature at its surface between 20 and

45 ° C, in particular at 37 ° C ± 0.2 ° C.

5. PSM according to one of claims 1 to 4, characterized in that the optical observation device comprises lighting means (8) capable of illuminating the sample in the observation area, and collection means of light (9) allowing the observation of a sample placed in this area.

6. PSM according to claim 5, characterized in that the light collection device (9) comprises an autofocus camera.

7. PSM according to claim 5 or 6, characterized in that the light collection device is placed under the first window (7) of the plate (6).

8. PSM according to claim 5 or 6, characterized in that all or part of the lighting and / or light collection means are located behind one or more windows separate from the first window (7) and integral with one at least walls, in particular of the upper wall (4).

9. PSM according to any one of claims 5 to 8, characterized in that the light collection device (9) is arranged to ensure several magnifications of the image between 10 and 1000, in particular between 10 and 400.

10. PSM according to claim 9, characterized in that the light collection device (9) further comprises a fine focusing system at each magnification.

11. PSM according to claim 10, characterized in that the fine-tuning system is controlled from a dashboard (10) located outside the workspace and / or integral with one walls defining the workspace.

12. PSM according to any one of claims 5 to 11, characterized in that the light collection device (9) is connected to a device for recording the collected images.

13. PSM according to claim 12, characterized in that the image recording device is a computer equipped with data storage means.

14. PSM according to any one of claims 5 to 13, characterized in that it comprises an observation screen (11) integral with one of the walls defining the working space, said screen making it possible to view the images collected by the light collection device (9).

15. PSM according to claim 14, characterized in that the observation screen (11) is a flat screen integrated into the rear wall (3) of the working space.

16. PSM according to any one of claims 1 to 15, characterized in that it also comprises a zone for gassing the samples, comprising a gas inlet (12), an enclosure allowing the confinement of the gas (13), and a connection device (14) connecting said gas inlet (12) to said enclosure (13).

17. PSM according to claim 16, characterized in that the enclosure (13) and the connection device (14) connecting the gas inlet (12) to said enclosure (13) are easily removable.

18. PSM according to claim 17, characterized in that the enclosure (13) and the connection device (14) connecting the gas inlet (12) to said enclosure (13) are inserts.

19. PSM according to one of claims 16 to 18, characterized in that the gas inlet (12) is integrated into one of the vertical walls (2) and (3) defining the workspace, and in that the enclosure (13) is a transparent bell, connected to the gas inlet (12) by a pipe.

20. PSM according to one of claims 16 to 19, characterized in that the connection device (14) connecting the gas inlet to the enclosure comprises a protective flange (15) intended to protect the gas inlet ( 12) projections.

21. PSM according to any one of claims 1 to 20, characterized in that it further comprises data entry means.

22. PSM according to claim 21, characterized in that said data entry means comprise a touch keyboard (16) integral with the floor (1) defining the workspace.

23. PSM according to claim 21, characterized in that said data entry means comprise a screen and a pointer control area, said control area being secured to the floor (1), and said pointer being suitable for allowing the activation of predefined keys materialized on the screen.

24. PSM according to any one of claims 21 to 23, characterized in that the data entry means are connected to a computer.

25. PSM according to any one of claims 1 to 24, characterized in that the walls (1-5), defining the working space are flat and made of smooth, washable materials and resistant to cleaning products.

6. PSM according to any one of claims 1 to 25, characterized in that the floor (1) consists of one or more removable and disposable elements or sterilizable by autoclave.