Techniques for studying adipocytes.

Various fixatives as well as tissue and slide handling procedures have been evaluated in attempts to demonstrate adipocytes histochemically while maintaining cell and tissue integrity. The optimal procedure for analysis of immature adipose depots consists of the following steps: 1) fresh, unfixed tissues are rapidly in isopentane quenched in a liquid nitrogen bath; 2) cryostat sections are cut, removed from the knife with a room temperature slide, and then air dried for 5-10 minutes; 3) slides can be stained directly with picro-Ponceau or toluidine blue procedures or with oil red O following fixation for 30 minutes in cold (4 C) 10% formalin-CaCl2 (1.25%). For analysis of mature rat adipose depots steps 2 and 3 are modified as follows: 2) cryostat sections are removed from the knife with a cold slide (-20 C) and dried for 30 minutes at 4 C; 3) the mounted sections are stained with oil red O following fixation for 30 minutes in cold (4 C) 10% formalin-HgCl2 (2.5%). When procedures described above for immature adipose depots are combined with esterase staining, adipocyte cytoplasm is clearly demonstrated. These procedures allow the routine use of fresh frozen, unfixed cryostat sections in studies of adipose cellularity.