RESUMO
Numerical changes in the distribution of immature mast cells in the different ovarian compartments of the immature and adult ovary of rats Rattus rattus have been studied using alcian blue-safranine staining method. Maturational changes of mast cells from the first day of birth to maturity of animal and during the oestrous cycle have also been determined. Immature animals were divided into five groups on the basis of their increasing body weights. All the mast cells in the ovary group of I and II were immature as they showed positive staining with alcian blue and appear to possess the proliferative capacity. Cells containing safranine-stained red granules were first observed in group III rats and they appeared simultaneously in hilus, medulla and cortical regions of the ovary. Total counts of immature mast cells per ovary increased significantly from group I to II, decreased in group III and thereafter no change was recorded in group IV and V. Mast cells in the ovary of rats of group I and II were mainly localized in the stroma, followed by medulla and hilus. In mature rats major part of cell population was concentrated in the hilar region. Alcian blue-positive mast cells were observed at all stages of oestrous cycle, their number per ovary was found to be highest at oestrus, intermediary at dioestrus and metoestrus, and lowest at pro-oestrus which suggested that new population of mast cells continue to differentiate in the cycling rat ovary.