Local effect of the corpus luteum on ovarian follicular functional and morphological features in the goat

Ovaries of unilaterally ovulated goats (n=21) were used to study follicular morphological features (proportion and degree of atresia, oestradiol produ ction in vitro and progesterone production of granulosa cells in culture). Follicles were dissected out and classified as small (1-2 mm), medium (2-4 mm) and large (>4 mm). Morphological and physiological features were compar ed in each size class between ovaries bearing and not bearing corpora lutea (CLO and NCLO, respectively). Within the same size class, there was no dif ference in proportion or in degree of atresia, between CLO and NCLO. A sign ificant effect of follicular size on oestradiol production in vitro was det ected, but no effect of the corpus luteum was found. Finally, progesterone production of granulosa cells in culture was significantly higher in CLO th an in NCLO after 24 h (p < 0.05) and also after 90 h (p < 0.01) of culture. This higher progesterone production by CLO granulosa cells in culture coul d be explained by local influence of the corpus luteum stimulating the ster oidogenic activity but not aromatase activity. Further studies are needed t o clarify possible factors and pathways for this local effect of the corpus luteum upon follicular physiology.