QUANTITATIVE AND CYTOCHEMICAL STUDIES OF MAST-CELL PROTEASES IN RAT OVARIES AND UTERI IN VARIOUS REPRODUCTIVE STATES

A role for mast cell proteases (RMCP I and II) in the cyclical remodel ling of ovarian and uterine tissues of rats was investigated in the oe strous and pregnancy cycles using immunocytochemistry and enzyme-linke d immunosorbent assays. The concentrations of RMCP I exceeded that of RMCP II by 100-fold in both tissues, but were always much higher in ut eri than ovaries. Most of the protease activity in the uterus was loca ted in the myometrium, whereas it was more focally distributed in the hilus and medulla of the ovary. Protease activity was confined to mast cells identified by metachromatic staining and no single cell contain ed both proteases. The concentrations of RMCP I and II in the two orga ns did not fluctuate throughout the 4-day oestrous cycle. Neither were RMCP I concentrations in the uterus altered by administration of diet hylstilboestrol to ovariectomized animals, although total amounts per uterus were substantially greater than in controls. Concentrations of RMCP I were substantially reduced in the uterus after day 6 of pregnan cy and rose during the puerperium. The reduction was greater in pregna nt than in pseudopregnant horns and tended to be lower in the vicinity of conceptuses than between them. The physiological significance of t he lower mast cell protease concentrations is unclear, although their absence may contribute to the decreased protein catabolism during preg nancy.