Abstract
Effects of the reproductive activity upon major organ weights and ovarian histology were examined in the inbred wild-colored mastomys (Praomys coucha), MWC. The liver, ovary and spleen weights increased during pregnancy and kept the increased levels until weaning of the young in the former 2, but not in the last. The most characteristic histological changes were observed in the corpora lutea and interstitial cells. The corpora lutea changed in both size and number according to the reproductive status. The interstitium was meagre in virgins as observed in other laboratory rodents, but expanded during pregnancy. It contained two types of interstitial cells. One was characterized by light cytoplasm and the other by dark cytoplasm. The latter increased in number during pregnancy and occupied the interstitium exclusively. These changes suggested that the interstitial (steroidogenic) cells in the mastomys might have a unique and distinctive turnover mechanism as did those constituting the zona reticularis and border zone in the female mastomys adrenal cortex.
