The Pattern of Follicular Growth and Atresia in the Ovine Ovary

Abstract

The ovaries of 21 2-year-old Merino ewes at various stages of the oestrous cycle were serially sectioned and all follicles > 0�5 mm in diameter were counted and measured. The mean number of normal follicles > 0�5 mm in diameter was 19� 9 per ewe, of which 8�7 were > 1 mm in diameter. The mean numbers of follicles > 0�5 mm in diameter in 'early', 'advanced' and 'late' stages of atresia were 4� 6, 9� 0 and 12� 3 respectively. Early atresia was rarely seen in follicles < 1 mm in diameter; the greatest incidence was in follicles of diameter 1� 5-2' 5 mm.