The Microm HM560 is a cryostat with electronic temperature control down to -35°C. It also offers fast freezing with Peltier down to -55°C and a spacious, easy-to-clean cooling chamber. We chose this model for our laboratory after a meticulous search for the best cryostat available. We tested several models and finally opted for the Microm HM 560 cryostat without hesitation; I am pleased to detail its advantages.
We use this cryostat to slice fresh or PFA- and FineFix-fixed pieces of human and animal intestine. We create 10 to 30 um slices which we analyze using mainly double immunolabelings (with primary and secondary antibodies) targeting neurokinin receptors, G proteins, etc.; staining is followed by observation on a confocal microscope. Our cryostat is a manual model with wheel-controlled coarse feed, but various configurations like motorized sectioning and a Vacutome system are also available.
Nobody is surprised to see double refrigeration in recent models of cryostats, one for the tissue block and another for the cooling chamber. However, Microm optimized the refrigeration by incorporating a unique refrigeration system into the HM 560 cryostat: The specimen and knife, and not the chamber, have independent refrigeration systems and may be set as low as -50°C and -35°C, respectively. Moreover, the Peltier cooling which is integrated into the knife allows easily programmable temperature setting for sectioning. Knife temperature can be increased and decreased more rapidly than the temperature of the chamber in other models. This feature is very important when you cut different types of tissues, each requiring a specific temperature. Also, if the tissue block was fixed before freezing, the fixative may influence the optimal cutting temperature too. The low temperature is also maintained in the chamber and is equal to the temperature of the knife.
The automatic micro/macro feed system is outside the freezing chamber and guarantees the highest precision and flexibility: From 0.5 to 500 um. The precision is the same, should you use the Fine or Trim sectioning mode, but the range of thickness is different: from 0.5 to 100 um and from 5 to 500 um, respectively. The expanded thickness range and horizontal feed of 40.000 um makes many applications possible.
The design of the cryostat is ergonomic. There is a large, reclining electronic display with buttons for each function and a cooling chamber with a removable container which permits simplified cleaning and disinfection. The absence of any screw in the chamber is noteworthy as this leaves room for the innovative magnetic knife and object holders.
I would like to mention 2 other very valuables features. First, the presence of the freezing/detaching device which is equipped with Peltier cooling resolves the problem of the often difficult detachment of tissue blocks from the metal support used to fix the object on the holder. The temperature is quickly reversible, and you can pass from object cooling to object detaching in seconds. You only have to put the support with the block onto the plate, push the button “Detach” and let the temperature of the device attain 6°C (it takes generally only several seconds). If I can give a piece of advice, do not freeze your specimens using the freezing device of the cryostat as the freezing is too slow and reduces the probability of conserving tissue morphology. I have observed that tissue pieces of 0.5 cm3 and larger are better frozen in liquid nitrogen. The cryostat freezing device is, however, a very nice feature which simplifies mounting blocks on the cryostat supports. The second wonderful feature is the automatic approach system (ACA). Based on the electrical resistance, this function advances the knife to the point where the object is nearly touched. It really saves time.
Overall, the HM 560 is designed to provide excellent performance and I do not hesitate to recommend it.
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Alexandra Khomitch-Baud
Scientist
Cellular Imaging Department
Biovays
France
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