Bioscientifica Proceedings

Abstract unavailable© 2009 Society for Reproduction and Fertility...

The physiological mechanisms controlling ovulation rate in mammals involve a complex exchange of endocrine signals between the pituitary gland and the ovary, and a localized exchange of intraovarian hormones between the oocyte and its adjacent somatic cells. The discoveries in sheep of mutations in bone morphogenetic protein 15 (BMP15) and bone morphogenetic protein receptor type IB (BMPR-IB) together with recent findings on the physiological effects of growth differentiation ...

Summary. In cattle we have noted that the antral follicle count (AFC, follicles ≥3 mm in diameter) varies greatly among animals (from 5 to 50), is repeatable within animals, and is highly correlated with the total number of healthy follicles in ovaries. Also, animals with low AFC have higher serum concentrations of FSH and LH, but lower concentrations of Anti-Mullerian Hormone, progesterone and androgens than animals with high AFC. We have investigated t...

Summary. The life time reproductive performance of 2 flocks of Merino crossbred ewes pinealectomized at 7–60 days of age, and maintained in South Australia did not differ from that of sham-operated control animals kept in the same flocks. The pineal gland is therefore not a major determinant of reproductive success, but a role for the pineal in adjusting breeding activity to season is not excluded. It was confirmed that pineal denervation of adult ewes ...

Summary. Recent research clearly shows that fusion genes can be microinjected into a pronucleus of an ovum and integrate into the pig genome. Animals with such fusion genes are called ‘transgenic’. The percentage of injected ova that developed into transgenic pigs varied among experiments from 0.31% to 1.73%. The percentage of transgenic pigs that expressed the fusion gene ranged from 17% to 100%.Eleven different regulatory s...

The autocrine and paracrine role of the insulin-like growth factors (IGFs) and epiderrnal growth factor (EGF)-related peptides in pig ovary are reviewed. For convenience, each of these regulatory systems is divided into several interactive components: regulated expression of the growth factors, growth factor reception at the cell surface and intracellular action of the growth factors. In addition, the concept of regulated bioavailability and targeting of growth factors in...

Summary. Development of the corpus luteum (CL) is vital for the early increase in postovulatory progesterone that drives embryo development and the successful establishment of pregnancy. Following ovulation, rapid and dramatic cellular reorganisation and intense angiogenesis are required to support the timely transition to progesterone secretion. In addition to inherent physiological challenges, this process is sensitive to any imbalance in metabolism or healt...

Structural patterning and functional programming of uterine tissues are mechanistically coupled. These processes ensure anteroposterior differentiation of uterine tissues from adjacent segments of the developing female reproductive tract (FRT) and radial patterning that establishes uterine-specific histoarchitecture and functionality. Uterine organogenesis begins prenatally and is completed postnatally. Genes required for FRT development include Pax2, Lim 1<...

Parturition is a process which, when set into motion, occurs to completion. This review concerns the control of parturition in ruminants. Parturition is an endocrine event, dependent upon the activation of the fetal hypothalamus–pituitary–adrenal (HPA) axis. In sheep and other ruminants, increases in plasma concentrations of cortisol induce the activity of 17-hydroxylase and 17,20 lyase in the placenta, increasing the biosynthesis of oestrogen relative to progester...

Summary. Mastitis has a deleterious effect on reproductive responses and fertility of dairy cows, which depends on whether it occurs before or after artificial insemination (AI). Subclinical intramammary infection (IMI) before AI reduced steroid concentrations in the preovulatory follicle of approximately one third of lactating cows, and was associated with low expression of major steroidogenic genes. Consequently, IMI induced an attenuated LH surge and delaye...