Bioscientifica Proceedings

Summary. In four studies secretion patterns of LH, FSH, prolactin, testosterone and progesterone were measured in male and female cattle to determine endocrine changes associated with sexual maturation. Two periods of increasing gonadotrophin secretion were observed, the second one coinciding with puberty. A short luteal phase of 8–12 days precedes the first oestrus at 10–11 or 14 months of age. The testosterone values of the bulls increased with age...

Development of the corpus luteum (CL) in ruminants occurs in a rapid and time-dependent manner within 1 week after ovulation, with morphologic and biochemical changes in the cells of the theca interna and granulosa cells of the preovulatory follicle. These changes involve luteinisation of steroidogenic cells and angiogenesis to establish normal luteal function (progesterone secretion). The CL is composed of a large number of vascular endothelial cells, large and small steroido...

Summary. The processes of follicle development and puberty are closely related, and both are associated with maturation of the hypothalamic—pituitary—ovarian axis. Prenatal development of the ovary is independent of gonadotrophic stimulation. Beyond 60 days of age (postnatally), tertiary follicles develop and gonadotrophins begin to influence ovarian follicular development. Negative feedback regulation of pituitary gonadotrophins by ovarian secretions dev...

In vitro culture has provided new information on the mechanisms involved in fertilization where two completely different cells fuse together. At the same time, results obtained in vitro have led to new questions. Does the follicle influence the final maturation process of the oocyte and does the oviduct regulate the normal behaviour of spermatozoa? Recent studies indicate a critical influence of both the follicular compartment and the oviduct on the norm...

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

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

© 2009 Society for Reproduction and Fertility...

Determining the stage- and tissue-specific patterns of gene expression shown by the embryo and fetus will provide information about the control of normal development. Identification of alterations in these patterns associated with specific abnormal phenotypes will also be informative regarding the underlying molecular mechanisms. In addition, qualitative and quantitative changes in gene expression that deviate from the norm may provide a potential marker system for predicting ...

While the role of oestradiol and progesterone in the control of GnRH pulsatile secretion and generation of the preovulatory GnRH surge to induce release of the LH surge has been fully investigated, less attention has been given to changes in the pituitary gland that may sensitize gonadotrophs to switch from pulsatile release to surge release of LH, in particular. Furthermore, in the follicular phase while pulsatile secretion of LH is maximal, FSH secretion is reduced, yet both...

Summary. The progress in understanding the metabolism of the ruminant cumulus-oocyte complex (COC) from large antral follicles has progressed significantly in the past decade. In particular, new insights in the importance of lipid metabolism, ß-oxidation and its relationship to oxidative phosphorylation within oocytes have emerged. This provides opportunities for tapping into the potential yield of ATP from lipid metabolism, as ATP content is a major dete...