Abstract:
A loading station ( 100, 200 ) for translocating a frozen sample for electron microscopy, encompassing a chamber ( 104, 204 ), open toward the top, that is fillable at least partly with a coolant, the chamber ( 104, 204 ) comprising in its side wall at least two ports ( 101   a,    102   a,    103   a ) each for different sample transfer devices ( 101, 102, 103 ), the ports ( 101   a,    102   a,    103   a ) permitting introduction of a frozen sample into the chamber ( 104, 204 ) via a selected sample transfer device and withdrawal of a frozen sample from the chamber via a respective different sample transfer device; and wherein a receptacle ( 108, 208 ) for at least two differently configured sample holders ( 109, 110 ) is arranged in the chamber ( 104, 204 ), the at least two sample holders ( 109, 110 ) being detachably fastenable to at least one of the sample transfer devices ( 101 ) for introduction of the frozen sample into the chamber ( 104, 204 ) and for withdrawal of the frozen sample from the chamber ( 104, 204 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is the U.S. national phase of International Application No. PCT/EP2015/066106 filed Jul. 15, 2015, which claims priority of German Application No. 10 2014 110 722.5 filed Jul. 29, 2014, the entirety of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a loading station for translocating a frozen sample for electron microscopy, encompassing a chamber, open toward the top, that is fillable at least partly with a coolant. 
       BACKGROUND OF THE INVENTION 
       [0003]    Cryofixation is a sample preparation method often used in electron microscopy. In this, a water-containing sample is frozen very rapidly to a temperature below −150° C. (cryofixed), i.e. it is cooled very quickly while avoiding the formation of ice crystals. Cryofixation has proven to be particularly suitable for investigations of structural biology. The specimens to be investigated, for example cells, enzymes, viruses, or lipid layers, are thereby embedded in a thin, vitrified layer of ice. The great advantage of cryofixation is that the biological structures can be maintained in their natural state. For example, a biological process can be halted at any arbitrary point in time by cryofixation and investigated in that vitrified state, for example using a cryo-electron microscope and/or in a light microscope with corresponding sample cooling. Correlative methods between a light microscope and electron microscope, also referred to as “CLEM” (correlative light-electron microscopy), make it possible, for example, firstly to observe a biological sample in a light microscope until the desired state is reached. The sample is then transferred into a cryopreparation apparatus and cryofixed for electron microscopy observation. In another variant of CLEM, the light-microscopy investigation is performed on the already cryofixed sample. Cryofixed samples can furthermore also be subjected, in a manner known per se, to further preparation steps, for example processing using freeze-fracture technology (freeze-etching) and/or coating techniques. 
         [0004]    In order not to impair the quality of the frozen samples, it is very important that they be transferred in cooled and contamination-free fashion between the processing devices being used (for example cryofixation device, freeze fracture apparatus, coating apparatus), and the analysis devices (e.g. cryo-electron microscope, cooled light microscope). 
         [0005]    The brochure for the “Leica EM VCT100” vacuum cryo-transfer system (manufacturer: Leica Microsystems), which is accessible via the link http://leica-microsystems.com/fileadmin/downloads/Leicag%20EM%20VCT100/Brochures/Leica EMVCT100 Brochure EN.pdf, discloses a liquid nitrogen-cooled loading station to which a transfer container (Leica EM VCT100 Shuttle) can be coupled. A sample holder is detachably fastenable to a slide rod of the transfer container. The sample holder can be transferred out of the cooled transfer container into a cooled chamber of the loading station by displacement of the slide rod. A receptacle for retaining the sample holder is arranged inside the chamber of the loading station. The very small frozen electron microscopy samples, which are usually located in a manner known per se on an electron microscopy sample carrier (e.g. a grid or a pin for scanning electron microscopy), are manually introduced into the liquid nitrogen-cooled chamber of the loading station. The sample carrier having the sample is removed, for example with a forceps, and fastened in the sample holder. This process occurs in a cooled state, so that the frozen sample does not thaw or melt and thus become unusable. The transfer container having the sample holder and the sample carrier with a sample is then uncoupled from the loading station and attached to a corresponding apparatus (e.g. freeze fracture apparatus, cryo-electron microscope) for further processing or analysis. 
         [0006]    The number and capabilities of sample processing operations, analyses, and corresponding devices in electron microscopy is constantly increasing. Translocation of the sample into a differently configured sample holder, or into a differently configured sample transfer device, is normally also necessary for the various applications. With the known loading station described above, translocation of a sample from one sample holder into a differently configured sample holder for a different application is not possible. It is also possible to attach only a single transfer container. Users therefore usually make do by transporting the sample to various installation sites in small containers and in liquid nitrogen. This not only involves a considerable expenditure of time, but encompasses critical working steps in which the samples can become damaged or contaminated. The working step in which the error occurred is then often not perceptible. The known loading station furthermore has no temperature monitoring, and coolant replenishment occurs manually. 
       SUMMARY OF THE INVENTION 
       [0007]    An object of the invention is therefore to make possible maximally contamination-free translocation of a frozen sample from one sample holder into a differently configured sample holder, or into a differently configured sample transfer device, which is provided for a different application. 
         [0008]    This object is achieved with a loading station of the kind recited previously, which according to the present invention is characterized in that the chamber comprises in its side wall at least two ports each for different sample transfer devices, the ports permitting introduction of a frozen sample into the chamber via a selected sample transfer device and withdrawal of a frozen sample from the chamber via a respective different sample transfer device; and that a receptacle for at least two differently configured sample holders is arranged in the chamber, the at least two sample holders being detachably fastenable to at least one of the sample transfer devices for introduction of the frozen sample into the chamber and for withdrawal of the frozen sample from the chamber. 
         [0009]    Thanks to the invention, very largely contamination-free and time-saving translocation of frozen samples for electron microscopy between the (usually differently configured) sample holders of the individual processing devices or analysis devices, at temperatures below −150° C., is possible. 
         [0010]    In most cases the frozen sample is mounted on an electron microscopy sample carrier, the conformation of which depends on the respective application. The term “sample carrier” therefore refers to all carriers suitable for electron microscopy and for electron microscopy sample preparation. Sample carriers for electron microscopy are sufficiently familiar to one skilled in the art. They are, for example, pin-like carriers for scanning electron microscopy, or small mesh-shaped carriers that are generally referred to as “grids.” The grids can comprise variously shaped holes (honeycombs, slits, etc.) or a lattice of a defined mesh size, and/or can be coated with a film (e.g. coated grids of the Quantifoil company) and/or can be carbon vapor-coated. Other carriers that are likewise used in cryopreparation of electron microscopy samples are, for example, sapphire disks as described in EP 1 267 164 B1. 
         [0011]    The sample carrier having the sample can in turn be detachably fastened in a sample holder of the sample transfer device. The sample holder either can be fixedly connected to the sample transfer device (e.g. a sample holder for transmission electron microscopy, such as a cryo-TEM holder of the Gatan company (model  626  single tilt liquid nitrogen cryo-transfer holder)), or it can be detachably couplable to the sample transfer device and can therefore be replaceable. One known sample transfer device, on which variously configured sample holders that are each used for different applications, is the Leica EM VCT100 Shuttle (manufacturer: Leica Microsystems) already recited above. The Leica EM VCT100 Shuttle is also suitable for attachment to the loading station in accordance with the invention. The sample holder that can be coupled to the Leica EM VCT100 Shuttle is selected depending on the sample carrier being used (e.g. a grid). Alternatively thereto, certain applications provide that the sample is mounted directly on a surface of the sample holder, i.e. with no sample carrier such as a grid. 
         [0012]    The frozen samples are very small electron microscopy samples that can be translocated by means of the loading station according to the present invention into the different sample holders of the various processing devices or analytical devices. In the context of the correlative methods between a light microscope and electron microscope already mentioned above (CLEM, correlative light-electron microscopy), the frozen electron microscopy samples are investigated using both a light microscope and an electron microscope. The loading station according to the present invention also enables simple translocation of a frozen electron microscopy sample into sample holders that are embodied for light and electron microscopy. 
         [0013]    Usefully, the receptacle for the at least two differently configured sample holders is arranged in a floor region of the chamber. 
         [0014]    In an advantageous refinement, the receptacle encompasses a rotatable and tiltable spherical segment on which at least two differently configured sample holders are receivable. The sample holders are thus retained detachably in the receptacle. In a sub-variant, the receptacle is provided for exactly two differently configured sample holders, the spherical segment enabling a rotation around a vertical axis and a tilt. Alternatively thereto, the receptacle can also receive more than two sample holders, for example a receptacle on which four sample holders can be retained crosswise. 
         [0015]    In another refinement, the receptacle encompasses a displaceable carriage on which at least two differently configured sample holders are receivable. 
         [0016]    In an advantageous refinement, the loading station is characterized by a reservoir container for the coolant, which is connected to the chamber via a controllable inlet valve for the coolant. The controllable inlet valve is controlled, for example, via a stepping motor. Advantageously, a fill level sensor, with which coolant delivery from the reservoir container into the chamber is regulatable via the controllable inlet valve, is arranged in the chamber. Regulation of the coolant delivery into the chamber guarantees automatic replenishment of the coolant into the chamber, and thus continuous cooling of the samples. 
         [0017]    The loading station can furthermore comprise a temperature monitoring system, for example by way of a temperature sensor positioned in the chamber. 
         [0018]    Regulation of coolant delivery by means of the fill level sensor and the controllable inlet valve, and temperature monitoring by way of the temperature sensor, are accomplished using a control system that is constructed in a manner known per se and typically comprises a microcontroller as well as electronic components. 
         [0019]    Fill level deviations and temperature deviations in the chamber that go beyond a respective predefinable temperature range and fill level range can be compensated for by the control system. It is furthermore also possible for deviations to be brought to an operator&#39;s attention as an alarm signal. 
         [0020]    The loading station can furthermore encompass an operating console for the input of instructions for the control system. Such instructions encompass, for example, the programming of coolant delivery and of temperature. 
         [0021]    The coolant (also referred to as a “cryogen”) is a liquefied gas such as liquid nitrogen (LN2) or liquid air, preferably liquid nitrogen. 
         [0022]    The chamber of the loading station is configured to be open toward the top. Continuous evaporation of the coolant results in formation of a flow of cold gas that emerges from the chamber and thus prevents air from entering. In the context of a particularly advantageous variant, the loading station comprises a breath shield that is positioned above the chamber that is open toward the top. The breath shield prevents water vapor from freezing in or on the chamber. The emerging flow of cold gas and the breath shield prevent contamination of the samples. 
         [0023]    In an advantageous variant, an air lock, which by means of a vacuum pump respectively permits evacuation of a sample transfer device as well as transfer of the frozen sample into an evacuatable sample transfer device and transfer of the frozen sample out of an evacuatable sample transfer device, is attachable to the chamber. Transfer under vacuum prevents contamination, and ensures better cooling of the sample (heat transfer only by radiation; almost no gas convection). One sample transfer device that is provided for cryo-transfer of frozen samples under vacuum or in an inert gas atmosphere is the aforementioned Leica EM VCT100 Shuttle (manufacturer: Leica Microsystems). Sample transfer devices for cryo-transfer under vacuum or in inert gas possess a container that, for transfer, is evacuated or can be filled with inert gas. The frozen samples are transferred into and out of the container via an air lock. Air locks of this kind are known per se and, for example, are constructed so that they are delimited by two slide valves, a vacuum being producible in the cavity between the slide valves by corresponding positioning of the slide valves. One slide valve can be fastened on the sample transfer device; the other slide valve is fastened on the loading station port. The air lock is formed by docking the sample transfer device onto the loading station port, for example via a hooking apparatus, and is sealed off from the outside, for example, by means of O-rings. The sample transfer device advantageously possesses a slide rod on which the sample holder having a sample is secured. The sample holder can then be transferred by means of the slide rod through the air lock from the loading station into the sample transfer device, and vice versa. 
         [0024]    In a variant, at least one of the ports is configured as a port for a sample transfer device that is provided for cryo-transfer of frozen samples under vacuum or in an inert gas atmosphere. One example of such a sample transfer device is the Leica EM VCT100 Shuttle (manufacturer: Leica Microsystems) recited above. 
         [0025]    In a further variant, at least one of the ports is configured as a port for a sample transfer device for transmission electron microscopy (TEM), for example as a cryo-TEM container sufficiently known to one skilled in the relevant art. Cryo-TEM holders are manufactured, for example, by the Gatan company (model 626 single tilt liquid nitrogen cryo-transfer holder). The port typically encompasses a continuous orifice and a fitting for the cryo-TEM holder. The orifice can be closed off, for example, with a stubble. 
         [0026]    In a further variant, at least one of the ports is configured as a port for a sample transfer device for light microscopy. This variant enables translocation of frozen electron microscopy samples from sample holders for electron microscopy into a sample holder for a light microscope, and is utilized especially in the correlative methods already mentioned previously which use both light microscopy and electron microscopy (CLEM). After translocation and transfer out of the chamber of the loading station, the frozen samples can be investigated by light microscopy with the aid of special cooled stages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING VIEWS 
         [0027]    The invention will be explained in more detail below with reference to a non-limiting example that is depicted in the attached drawings, in which: 
           [0028]      FIG. 1  is a perspective view of a loading station according to the present invention; 
           [0029]      FIG. 2  is a further perspective view of the loading station of  FIG. 1  from a different viewing angle; 
           [0030]      FIG. 3  is an enlarged perspective view of the receptacle for sample holders of the loading station depicted in  FIG. 1  and  FIG. 2 ; 
           [0031]      FIG. 4  is a perspective view of an alternative embodiment of the receptacle for sample holders; 
           [0032]      FIG. 5  is an enlarged view of a section through the loading station and the transfer device for cryo-vacuum transfer of  FIG. 1 ; and 
           [0033]      FIG. 6  is an enlarged view of a further section through the loading station and the transfer device for cryo-vacuum transfer of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]      FIG. 1  and  FIG. 2  are perspective views of a loading station  100  in accordance with the invention. Loading station  100  encompasses a chamber  104 , cooled with coolant (in the example, liquid nitrogen (LN2)), which is open toward the top. In the example shown, chamber  104  is embedded into a housing  115 . Chamber  104  is filled at least partly with LN2. Continuous evaporation of the coolant results in formation of a flow of cold gas that emerges from chamber  104  and thereby prevents the entry of air. A breath shield  106  is positioned above open region  105  of chamber  104 . The breath shield prevents water vapor from freezing in or on the chamber. The emerging flow of cold gas, and the breath shield, thus prevent contamination of the samples. The loading station furthermore possesses a magnifying lens (loupe)  118  that is positioned above chamber  104  and below breath shield  106 . 
         [0035]    The samples are very small frozen samples for electron microscopy, which are transferred into and out of chamber  104  in the frozen state at less than −150° C. and are translocated in chamber  104 . 
         [0036]    A receptacle  108  for two sample holders  109 ,  110 , which are configured to hold frozen samples, is arranged on chamber floor  107 . Receptacle  108 , which is shown enlarged in  FIG. 3 , is arranged on a spherical segment  111 . Spherical segment  111  is mounted tiltably and rotatably around a vertical axis, and can snap-lock into various positions by way of springs (not shown in further detail). 
         [0037]    Returning to  FIGS. 1 and 2 : chamber  104  comprises in its side walls a total of three ports  101   a ,  102   a , and  103   a  respectively for three different transfer devices  101 ,  102 , and  103 . Transfer devices  101 ,  102 , and  103  are attached from outside to ports  101   a ,  102   a , and  103   a . Ports  101   a ,  102   a ,  103   a  encompass openings through which frozen electron microscopy samples can be introduced from transfer devices  101 ,  102 ,  103  into the chamber and withdrawn. Unused ports are each closed off by a slider (not depicted in further detail). 
         [0038]    In the example depicted, transfer device  101  is the Leica EM VCT100 Shuttle (manufacturer: Leica Microsystems) mentioned above, i.e. a transfer container that is provided for cryo-transfer of frozen samples under vacuum or in an inert gas atmosphere. Transfer device  101  possesses a slide rod  113  with which a sample holder can be introduced from the cooled transfer device  101 , through the opening of port  101   a , into chamber  104 . Transfer of the sample into and out of transfer device  101  occurs via an air lock  119  described in detail below in  FIGS. 5 and 6 . 
         [0039]    In the example depicted, transfer device  103  is a transfer device for light microscopy, and likewise possesses a slide rod  112  with which a sample holder can be introduced through the opening of port  103   a  into chamber  104 . 
         [0040]    Transfer device  102  is a cryo-TEM sample holder (e.g. model 626 single tilt liquid nitrogen cryo-transfer holder of the Gatan company), in which that end of the TEM specimen holder in which the sample is received can be inserted through the opening of port  102   a  into chamber  104 . 
         [0041]    Loading station  100  shown in the example possesses a total of three different ports for three different transfer devices. There can also be, however, only two different ports or also more than three different ports, for example four or five different ports. The number and respective configuration of the ports depend on the transfer containers to be attached; the combination of the type of port and the transfer container is correspondingly selected depending on the application spectrum. 
         [0042]    In the example depicted, only transfer device  101  communicates with receptacle  108  for sample holder  109 ,  110 . Tilting of receptacle  108  with the aid of the rotatable and tiltable spherical segment  111  is necessary because transfer device  101  is placed obliquely onto loading station  100  (see  FIG. 2 ); and for translocation of the sample, sample holder  109  or  110  is uncoupled from slide rod  113  via a bayonet, immobilized in receptacle  108 , and only then brought into a horizontal processing position. 
         [0043]    The translocation of a sample from sample holder  109  to the different sample holder  110  will be described below. In  FIGS. 2 and 3 , sample holders  109 ,  110  are retained in receptacle  108 , sample holder  109  being directed toward transfer device  101  and having previously been uncoupled therefrom. A sample located in sample holder  109  can then be translocated manually, e.g. with a forceps, into sample holder  110 . A selection of sample holders for various applications in scanning electron microscopy (SEM) is presented in the brochure for the “Leica EM VCT100” vacuum cryo-transfer system (manufacturer: Leica Microsystems), which is accessible via the link http://leica-microsystems.com/fileadmin/downloads/Leica%20EM%20VCT100/Brochures/Leica EMVCT100 Brochure EN.pdf. The analytical and processing methods used in electron microscopy are very varied, and the configuration of the sample holders is correspondingly varied. 
         [0044]    After translocation, spherical segment  111  is rotated 180° so that sample holder  110  is now directed toward transfer device  101 . Spherical segment  111  is then tilted, and sample holder  110  having the sample can then be coupled onto that end  113   a  of slide rod  113  which extends into chamber  104 , and removed from chamber  104  by pulling slide rod  113  back. Alternatively thereto, the sample can also be translocated from sample holder  109  into the respective sample mounts of transfer devices  102  and  103  for other analytical or processing steps. 
         [0045]    Loading station  100  furthermore comprises a reservoir container  114  for coolant, which container is likewise embedded into housing  115 . Reservoir container  114  can be closed off with a cover  116 . Reservoir container  114  is connected to chamber  104  via a controllable inlet valve (not depicted in further detail) for coolant. The controllable inlet valve is embodied in a manner known per se and is controlled, for example, via a stepping motor. Also arranged in chamber  104  is a fill level sensor, embodied in a manner known per se and likewise not depicted, with which coolant delivery from reservoir container  114  into chamber  104  is regulatable by way of the controllable inlet valve. Regulation of coolant delivery into chamber  104  ensures automatic replenishment of coolant into chamber  104 , and thus continuous cooling of the samples. Loading station  100  furthermore comprises a temperature monitoring system of a kind known per se, for example a temperature sensor positioned in the chamber. 
         [0046]    Regulation of coolant delivery by means of the fill level sensor and the controllable inlet valve, and temperature monitoring by way of the temperature sensor, are accomplished using a control system (not depicted in further detail) that is configured in a manner known per se and typically comprises a microcontroller as well as electronic components. Fill level deviations and temperature deviations in chamber  104  that go beyond a respective predefinable temperature range and fill level range can be compensated for by the control system. It is furthermore also possible for deviations to be brought to an operator&#39;s attention as an alarm signal, for example as an optical or acoustic alarm signal. 
         [0047]    Loading station  100  furthermore encompasses an operating console for the input of instructions for the control system. Such instructions encompass, for example, programming of coolant delivery and of temperature. 
         [0048]      FIG. 4  is a perspective view of an alternative embodiment of a receptacle  208  for sample holders. Receptacle  208  is arranged on chamber floor  207  of a chamber  204  of a loading station  200 . Except for receptacle  208 , the construction of loading station  200  otherwise corresponds to that of loading station  100 . Receptacle  208  shown in  FIG. 4  encompasses a slider  211  in the manner of a carriage, in which a total of two sample holders are retainable. In  FIG. 4  only one sample holder  209  is detachably fastened in a first retention position  209   a  of receptacle  208 ; the second retention position  210   a  for sample holder  210  (not depicted) is unoccupied. Sample holders  209 ,  210  are embodied like sample holders  109 ,  110  described above. Slider  211  is mounted tiltably in order to couple sample holders  209 ,  210  to that end  113   a  of slide rod  113  of transfer device  101  which extends into chamber  204 . By displacing slider  211  in a direction that is indicated by arrow  212 , it is possible to position the respective sample holder  209 ,  210  with respect to slide rod  113 . 
         [0049]      FIGS. 5 and 6  are enlarged views of sections through loading station  100  and transfer device  101  of  FIG. 1 . As described above, transfer device  101  is the Leica EM VCT100 Shuttle (manufacturer: Leica Microsystems), i.e. a transfer container that is provided for cryo-transfer of frozen samples under vacuum or in an inert gas atmosphere. With the aid of slide rod  113  of transfer device  101 , a sample holder can be introduced from the cooled transfer device  101  through the opening of port  101   a , via an airlock  119 , into chamber  104  of loading station  100 . 
         [0050]    Air lock  119  encompasses two vacuum sliders  119   a ,  119   b . A vacuum can be created in cavity  120  between vacuum sliders  119   a ,  119   b , or in the interior of transfer device  101 , by corresponding positioning of vacuum sliders  119   a ,  119   b . Loading station  100  possesses a pump port  123  for a vacuum pump (not depicted in further detail) for respectively pumping out transfer device  101  and pumping out cavity  120 . Vacuum slider  119   a  is fastened on sample transfer device  101 ; vacuum slider  119   b  is fastened on port  101 a of loading station  100 . Air lock  119  is formed by docking sample transfer device  101  onto port  101 a of loading station  100 . 
         [0051]      FIG. 5  shows the two vacuum sliders  119   a ,  119   b  in a closed position. End  113   a  of slide rod  113  is pulled back into transfer device  101 . In this depiction, a sample holder  109 ,  110  is not located at present in transfer device  101 ; sample holders  109 ,  110  are positioned in the rotatable and tiltable spherical segment  111  of receptacle  108  (see also  FIG. 3  in this context). In order to introduce a sample present on a sample holder  109 ,  110  from loading station  100  with the aid of slide rod  113 , vacuum sliders  119   a ,  119   b  are opened. This is evident from  FIG. 6 , in which both vacuum sliders  119   a ,  119   b  are shown in an open position and slide rod  113  of transfer device  101  is advanced through air lock  119  into chamber  104  of loading station  100 . Sample holder  109  or  110  having the sample can now be fastened on end  113   a  of slide rod  113  and then pulled back into transfer device  101 . Vacuum slider  119   b  is then closed, and transfer device  101  can be pumped out by means of the vacuum pump via pump port  123 . Vacuum slider  119   a  is then also closed. Lastly, cavity  120  between sliders  119   a ,  119   b  can be aerated again, and transfer device  101  can be uncoupled from loading station  100  in order to transfer the sample into a processing device and/or analytical device. 
         [0052]    For transferring a sample out of an evacuated transfer device  101  into a processing device and/or analytical device, transfer device  101  is usually not aerated, since the processing device and/or analytical device is usually also under vacuum. Located on the processing device and/or analytical device is a port for transfer device  101  having a closed vacuum slider that corresponds in terms of construction to vacuum slider  119   b . Upon docking of transfer device  101  onto the processing device and/or analytical device, an air lock in accordance with air lock  119  described above is therefore once again formed. After the docking of transfer device  101 , the cavity between the two vacuum sliders  119   a ,  119   b  is pumped out and both vacuum sliders are then opened. Transfer of the sample out of transfer device  101  into the processing device and/or analytical device is accomplished with the aid of slide rod  113  under vacuum. 
         [0053]    As is also evident from  FIGS. 5 and 6 , transfer device  101  furthermore possesses, for cooling the sample, a coolant reservoir  122  (Dewar vessel  122 ) that can be filled with a coolant, typically liquid nitrogen. In order to cool the sample, Dewar vessel  122  is connected in a manner known per se, via thermally conductive copper components, to a cooled specimen stage  121  arranged in the interior of transfer device  101 . Sample holder  109 ,  110  having the sample is positioned on the cooled specimen stage  121  during the transfer between loading station  100  and a processing device and/or analytical device. 
         [0054]    The example shown is only one among many, and is not to be construed as limiting. 
       PARTS LIST 
       [0055]      100  Loading station 
         [0056]      101  Transfer device for cryo-transfer under vacuum or in inert gas atmosphere 
         [0057]      102  Transfer device for transmission electron microscopy 
         [0058]      103  Transfer device for light microscopy 
         [0059]      101 a Port for transfer device  101   
         [0060]      102   a  Port for transfer device  102   
         [0061]      103   a  Port for transfer device  103   
         [0062]      104  Chamber 
         [0063]      105  Open region of chamber  104   
         [0064]      106  Breath shield 
         [0065]      107  Chamber floor 
         [0066]      108  Receptacle for sample holders encompassing a tiltable and rotatable spherical segment  111   
         [0067]      109  Sample holder 
         [0068]      110  Sample holder 
         [0069]      111  Tiltable and rotatable spherical segment 
         [0070]      112  Slide rod of transfer device  103   
         [0071]      113  Slide rod of transfer device  101   
         [0072]      113   a  End of slide rod for transfer device  101   
         [0073]      114  Reservoir container for coolant 
         [0074]      115  Housing 
         [0075]      116  Cover of reservoir container for coolant 
         [0076]      117  Operating console 
         [0077]      118  Magnifying lens 
         [0078]      119  Air lock 
         [0079]      119   a  Vacuum slider 
         [0080]      119   b  Vacuum slider 
         [0081]      120  Cavity between vacuum sliders  119   a  and  119   b    
         [0082]      121  Specimen stage 
         [0083]      122  Dewar vessel 
         [0084]      123  Pump port for a vacuum pump 
         [0085]      200  Loading station 
         [0086]      207  Chamber floor 
         [0087]      208  Receptacle for sample holders encompassing a slider  211   
         [0088]      209  Sample holder 
         [0089]      210  Sample holder 
         [0090]      209   a  Retention position for sample holder  209   
         [0091]      210   a  Retention position for sample holder  210   
         [0092]      211  Slider 
         [0093]      212  Displacement direction of slider  211