The Effect of Gonadotrophin on Follicle Growth Initiation in the Neonatal Mouse Ovary

Abstract

The injection of gonadotrophin (PMSG) into mice between the ages of 3 and 6 days did not alter the number of follicles that started growth, suggesting that it did not provide the stimulus to small follicles to start their development. The injection of PMSG had no influence on small oocyte atresia.

Early Follicular Development and Atretic Changes in the Ovary of the Lamb? Fine Structure and Histochemistry

“…The PMSG did not have any marked effect on the structure of follicles, which is in general agreement with the results of Peters et al (1973) who reported that PMSG injected into mice had no effect on atresia of small oocytes or onset of growth of follicles, and Worthington and Kennedy (1979) who found that numbers of pre-antral follicles in lambs were unaffected by PMSG. In the latter study PMSG increased the number of vesicular follicles, perhaps by preventing atresia.…”

“…It is not clear what triggers the development-no significant changes in circulating gonadotrophin levels have been detected in our animals (Tassell et al 1978), although Foster et al (1972) reported elevations of luteinizing hormone in the post-natal period. It has been claimed that early follicular growth is independent of gonadotrophic stimulation (Peters et al 1973).…”

Reflections on the attainment of puberty in the rat: have circadian signals a role to play in its onset?

“…However, although many follicles are seen in the late stages of development (Jones & Krohn, 1961 ;Gates, 1971) only a small number ovulate (Ingram, 1962;Edwards et al, 1977;). An investigation of the effects of PMSG treatment on immature rats showed that, rather than increasing the numbers of large follicles, the hormone altered the balance between large and atretic follicles (Peters, Byskov, Lintern-Moore, Faber & Anderson, 1973 (McNatty, Hunter, McNeilly & Sawers, 1975) supported the previous findings and showed that an increase in FSH stimulated the granulosa cells to secrete oestradiol which in turn affected the growth of subsequent follicles (Baird, Baker, McNatty & Neal, 1975 fig. 4), whereas after 21 days of age values decrease and remain consistently low until the first preovulatory rise (Cheng & Johnson, 1974;Meijs-Roelofs et al, 1975b;Ojeda et al, 1976 (Text-fig.…”

Effect of hypophysectomy on mouse oocyte maturation in vitro

“…In young animals there is conflicting evidence regarding the necessity of gonadotrophins for the early stages of follicular growth (Price & Ortiz, 1944;Ben-Or, 1963;Eshkol & Lunenfeld, 1971/72;Baker & Neal, 1973;Peters, Byskov, Lintern-Moore, Faber & Anderson, 1973;Challoner, 1975;Purandare, Munshi & Rao, 1976;Lintern-Moore, 1977). Regardless of the necessity of gonadotrophins to initiate follicular growth in young animals, there is considerable evidence to suggest that either gonadotrophins or oestrogen must be present to ensure the normal morphological appearance of the growing granulosa cells.…”