Searchable, peer-reviewed, open-access proceedings from bioscience and biomedical conferences

bp0003rdr48 | Short Communications | REDR1994

A dual role for progesterone in the control of cyclicity in ruminants

Lamming GE , Mann GE

Abstract unavailable© 1995 Journals of Reproduction and Fertility Ltd...

bp0002rdr10 | Inhibin | REDR1990

Inhibin and oestradiol in the control of FSH secretion in the sheep

Baird DT , Campbell BK , Mann GE , McNeilly AS

Summary. In the sheep both FSH and LH are necessary for development of large antral follicles. The secretion of FSH is controlled by the negative feedback effect of two ovarian hormones, oestradiol and inhibin, acting at the level of the anterior pituitary. Both are derived from the granulosa cells of large antral follicles which are present in sheep ovaries throughout the oestrous cycle. FSH stimulates growth and mitosis and so the fully differentiated granul...

bp0004rdr24 | Embryonic Survival | REDR1998

The regulation of interferon-τ production and uterine hormone receptors during early pregnancy

Mann GE , Lamming GE , Robinson RS , Wathes DC

During early pregnancy the bovine embryo must produce a protein called interferon τ which inhibits the development of the luteolytic mechanism. Failure to inhibit luteolysis is the major cause of pregnancy loss in cows. The embryo must produce sufficient quantities of interferon τ by about day 16 to prevent luteolysis. Its ability to achieve this is largely dependent on the pattern of maternal progesterone production. A late rise in progesterone after ovulation or po...

bp0005rdr17 | Ovary-Uterus-Embryo Interactions | REDR2002

Follicle growth, corpus luteum function and their effects on embryo development in postpartum dairy cows

Wathes DC , Taylor VJ , Cheng Z , Mann GE

Absent or irregular ovarian cycles in lactating dairy cows are caused by failure to ovulate the dominant follicle at the appropriate time. The follicle then either regresses or develops into a cyst. This process can be triggered by a variety of metabolic and disease factors that act at the hypothalamus and pituitary gland to inhibit pulsatile LH secretion and the LH surge, and at the ovary to reduce follicular growth and oestradiol production. Cows of poor energy status have l...