HISTOLOGICAL DIFFERENCE BETWEEN RETROGRADE CORPORA-LUTEA OF PREGNANCYAND THOSE OF ESTRUS IN SIKA-DEER, CERVUS-NIPPON

Histological characteristics of retrograde corpora lutea (RCL) were ex amined for 105 pairs of ovaries of adult female sika deer, Cervus nipp on. Animals were captured in various seasons at Mt. Goyo, Iwate Prefec ture, the northern part of Japan. No histological differences were rec ognizable between RCL of pregnancy and retrograde accessory corpora lu tea (RACL), so far as examined by means of hematoxylin-eosin and Weige rt's resorcinfuchsin staining. They were both irregularly shaped and h ad well developed arteries in their thick capsules and a number of sma ll arteries in the parenchyma. These arteries showed the proliferation of elastic fibers showing elastosis in older RCL. The total number of these retrograded bodies per female increased with age, suggesting th at both the retrograded bodies would retain in the ovaries over 7 year s. RCL of estrus were small hyaline bodies scattered with some degener ated luteal cells in the hyaline matrix. They were distinguishable fro m those of pregnancy since the capsule and parenchyma in those of estr us were poorer in blood vessels. RCL of estrus appeared in October and November but were rarely seen in February and March, suggesting that they will disappear within three months after ovulation.