Bioscientifica Proceedings

Summary. Follicular heterogeneity has been demonstrated in both naturally cyclic and PMSG-stimulated immature gilts in that follicles in the selected ovulatory population differ in size by up to 2 mm and show marked variability in steroid content and gonadotrophin binding ability. This biochemical and morphological asynchrony continued into the immediate preovulatory phase and changes in response to the LH surge did not always occur simultaneously even in...

Manipulation of the pig genome is currently restricted to the random insertion of new DNA using pronuclear microinjection. This method suffers from a number of inherent limitations, the majority of which result from the inability to control the site at which the transgene becomes integrated. These drawbacks, together with the need to be able to target existing genes, will result in the replacement of pronuclear injection by new methods that have the capability to direct i...

Keywords: counter current transfer; ovary; oviduct; uterus; pig© 1990 Journals of Reproduction & Fertility Ltd...

The ovulatory process is extraordinary in that it constitutes a hormone- induced injury. Gonadotropin delivered via the follicular vascular wreath stimulates secretion of plasminogen activator by contiguous ovarian surface epithelial cells. A consequent elevation in interstitial plasmin activates collagenases and cleaves tumor necrosis factor α from its anchors on endothelium. Collagen fibril degradation and cellular death at the apex of the preovulatory follicle are hall...

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

Abstract unavailable© 2013 Context Products Ltd...

Summary. In the pig, establishment of pregnancy begins about 11-12 days after the start of oestrus. The ability of pig conceptuses to synthesize and release oestrogens during this period, as well as the ability of exogenous oestrogens to induce pseudopregnancy when administered from Day 11-15 of the oestrous cycle, provide evidence for an involvement of oestrogen in the maternal recognition of pregnancy in the sow. Oestrogen derived from the conceptus or ...

It is well established that the interferon τ (IFN-τ) family of proteins play a major role in preventing the regression of the corpus luteum during early pregnancy in ruminants, such as cattle, sheep and goats, but not in other mammals. These interferons, which are structurally and functionally related to type I interferon, such as IFN-α and -ω, arose from a duplication of an IFN-ω gene approximately 36 million years ago. The IFN-τ genes have conti...

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 two main types of cellular associations (type I, 2 generations of spermatocytes + 1 of spermatids; type II, 1 of spermatocytes and 2 of spermatids) occupy, respectively, more than half and about a third of the seminiferous epithelium cycle in rams and bulls. However, the duration of the cycle of the seminiferous epithelium and that of spermatogenesis differ between the species. A1 spermatogonia and Sertoli cell total numbers are highly ...