BRAIN MAST-CELL NUMBERS IN THE ALBINO-RAT - SOURCES OF VARIABILITY

Possible sources of variability in brain mast cell (MC) numbers were investigated experimentally in 36, 21-day-old albino laboratory rats (Rattus norvegicus). MC numbers did not differ significantly between brains that had been either: (1) immersed in ethanol-formalin-acetic acid fixative, (2) anesthetized with barbituate and then immersed in fixative, (3) anesthetized and perfused with saline and then fixative, or (4) anesthetized and perfused with saline-heparin and then fixative. Neither variations in perfusion or immersion times (within 35 min) after anesthesia, body weights nor sex significantly contributed to MC numbers. Significant litter differences accounted for 20 and 40% of the variance in MC numbers within the diencephalic leptomeninges and parenchyma, respectively, but did not influence cortical MC numbers. Differences between rats from the same litters accounted for 80 to 60% of the total MC number variance. Estimated total MC numbers within the diencephalic regions of different rats ranged from 3000 to 45,000. © 1979 Academic Press, Inc.