Effect of season, age and follicular phases on ovarian follicular population of ewes

A study was aimed at investigating the effect of season, age and follicular phases on total number of different phases of follicular populations on the ovary of ewes. Approach of histomorphometrical analysis of ovarian stained sections was adopted to know the total number of different phases of follicles on the ovary. Significantly higher number of small preantral follicles (SPFs), small antral follicles (SAFs) and large antral follicles (LAFs) were observed during breeding season as compared to large preantral follicles (LPFs) and atretic follicles (AFs) during non-breeding season. Significantly higher number of SPFs and LPFs were observed in ewes aged <1yr and 1 to 2 yr old ewes as compared to >2 yr old ewes. Significantly lower number of SAFs, LAFs and AFs were observed in <1yr and 1 to 2 yr old ewes as compared to >2 yr old ewes. The number of SAFs and LAFs was significantly higher in ewes in follicular phase than in luteal phase. However, there was significantly higher number of SPFs, LPFs and AFs during luteal phase than follicular phase. The study indicated that higher rate of development of follicles were noticed in ewe ovaries during breeding season, >2 yr aged and follicular phase than non-breeding season, ewes aged <1yr or 1–2 yr and luteal phase, respectively.