Hormonal requirements for the growth and differentiation of hamster preantral follicles in long-term culture

Abstract

Preantral follicles from pro-oestrous and oestrous hamsters were isolated enzymically (Stages 1-5) and by microdissection (Stage 6) and cultured for up to 168 h in the absence or presence of 100 ng ovine FSH or LH separately or combined or 1 or 10 micrograms progesterone or estradiol-17 beta in serum-free defined medium and exposed to 1 muCi [3H]thymidine for 24 h before termination. In the presence of insulin and hydrocortisone but not gonadotrophins, the morphology of follicles from pro-oestrous animals at Stages 1-4 (1-4 layers granulosa cells; no theca) were unaffected for up to 48 h whereas for Stages 5 (5-6 layers granulosa cells and developing theca) and 6 (7-8 layers granulosa cells and theca), atresia was prominent by 24 h. FSH significantly reduced the percentage of atretic follicles in Stages 1-5 throughout the culture period; but was effective only up to 96 h for Stage-6 follicles. LH was also effective, albeit to a lesser extent. FSH increased follicular labelling indexes during every 24-h labelling period and, during a pulse-chase period, follicular DNA content and granulosa cell numbers. FSH, but not LH, induced differentiation by 96 h of preantral follicles at Stage 6 into small antral stages (Stages 7-8). FSH and LH together induced almost the same effect as FSH alone. However, neither progesterone nor oestradiol had any significant long-term effects on DNA synthesis and oestradiol induced atresia beyond 24 h. Both FSH and LH induced follicular maturation in vitro as evident from increases in progesterone, androstenedione and oestradiol production. Follicles (Stages 1-4) collected from oestrous hamsters responded to FSH to a lesser extent than did those from pro-oestrous animals, possibly because of in-vivo exposure to periovulatory changes in gonadotrophins; however, an antrum formed in Stage-6 follicles by 72 h.

Effects of luteinizing hormone and follicle stimulating hormone on the developmental competence of porcine preantral follicle oocytes grown in vitro

“…In contrast, without FSH, preantral follicles failed to grow to the antral stage and none became mature oocytes. These results support previous studies [9,10,21,[24][25][26][27] suggesting that FSH plays an important role in the development of preantral follicles in vitro. FSH promotes preantral follicle growth by inducing granulosa cell proliferation and differentiation, because granulosa cell growth accounts for the majority of this follicle expansion [28].…”

“…In vitro, although several studies have demonstrated an important role for FSH in preantral follicle growth [9][10][11][12], other studies have indicated that treatment with FSH does not enhance preantral follicle growth [13,14].…”

Effect of cell shape and packing density on granulosa cell proliferation and formation of multiple layers during early follicle development in the ovary

“…Alternatively, it is possible that increased GC proliferation is due to increased levels of plasma follicle stimulating hormone (FSH) that is seen in prepubertal mice and peaks between days 10 and 16 (Dullaart et al, 1975;Halpin et al, 1986;Stiff et al, 1974), before declining to adult levels. This is feasible, because FSH-receptor mRNA is present in GCs from just after birth in mice (O'Shaughnessy et al, 1996), with levels peaking on day 10 pp (O'Shaughnessy et al, 1997), and FSH has been directly shown to stimulate GC proliferation in preantral follicles (Kreeger et al, 2005;Roy and Greenwald, 1989).…”

Initial and Cyclic Recruitment of Ovarian Follicles*

“…In another study, FSH treatment alone does not enhance granulosa cell division or steroidogenesis (111). In mice, FSH treatment enhances antral formation without increasing granulosa cell numbers in cultured follicles (134) whereas, in cultured hamster follicles, FSH treatment increases granulosa cell division (135). Using a cGMP analog to suppress apoptosis in preantral rat follicles in serum-free cultures, it was demonstrated that FSH treatment increases both follicle size and cell number (54).…”