A correlation between ovarian follicular maturity and anchorage-independent growth of bovine granulosa cells.

Previous studies have shown that a subset of bovine ovarian granulosa cells can proliferate to form clones of functional cells in suspension in a semisolid agar matrix, without the requirement for attachment to the substratum. These clonogenic anchorage-independent granulosa cells are responsive to epidermal growth factor and exhibit properties of a primitive progenitor cell population. We have used this assay system to analyze the proliferation of granulosa cells during ovarian follicular maturation.

Role of intrafollicular regulators and FSH in growth and development of large antral follicles in sheep.

Manipulation of circulating concentrations of hormones and ovarian follicle status was carried out on Day 11-12 of the oestrous cycle in sheep. All follicles visible on the ovary were ablated by cautery and ewes were treated with oestradiol or ovine follicular fluid (oFF) to suppress FSH or with PMSG to increase circulating gonadotrophic activity. One group underwent unilateral ovariectomy which greatly increased endogenous FSH and was the only treatment which significantly affected LH pulse frequency.

Seasonal changes in LH secretion in normal ewes and ewes which grazed oestrogenic clover.

Plasma luteinizing hormone (LH) concentrations were measured in normal (control) Corriedale X Merino (comeback) ewes and in clover-infertile comeback ewes which had grazed oestrogenic Yarloop clover (Trifolium subterraneum L. cv. Yarloop) for more than 4 years.

Relaxin inhibits the plateau component of the action potential in the circular myometrium of the rat.

The effects of relaxin on contractility and membrane potential of the longitudinal and circular smooth muscle layers of the uterus have been studied in vitro using oestrogen-treated, non-pregnant rats and pregnant rats. Relaxin decreased the amplitude of contractions induced by electrical stimulation of longitudinal myometrium by decreasing the duration of the bursts of action potentials. This effect was transient and tachyphylaxis always developed and was observed following injection of steroids and up to day 17 of pregnancy.

Differences in the reproductive endocrine status of ewes in the early post-partum period and during seasonal anoestrus.

More (P less than 0.05) post-partum acyclic ewes (8/9) showed evidence of pulsatile LH release than did seasonally anoestrous ewes (2/8). Mean plasma prolactin concentrations were higher (P less than 0.