Ovarian Follicular Atresia of Ewes during Spring Puerperium.

The distribution of healthy and atretic follicles on the ovarian surface of improved Valachian ewes 17, 24, and 32 days postpartum is reported in this study. The number of healthy follicles was higher on day 24 postpartum and their mean diameter tended to increase to day 32 (P < 0.05) with the greatest diameter of 5 mm. 78-81% of atretic follicles ≥3 mm in diameter was observed where apoptosis began in the follicular cells situated at the follicular cavity. The early atretic follicles are characterized by the presence of mitotic pictures. In one ewe 24 days postpartum, small regressive follicular cysts were observed. Contracting atresia is characterized by thickening of the theca interna even to 190 μm. Progesterone and oestradiol-17β concentrations were maintained at relatively low levels, but with no significant difference between the days postpartum.