Bioscientifica Proceedings

The objective of this study was to investigate the precocious sexual maturation in stoat females. We confirmed oestrus and successful mating in newborn stoats; and documented ovulation, preimplantation embryo development, embryonic diapause and implantation during first nine months of life. A total of 100 embryos at different stages of development were flushed from the oviducts and uterine horns obtained from female stoats (Mustela erminea) between day 26 and day 251 ...

Summary. Comparison of the timing of pig preimplantation development, alterations’ in the ultrastructure of embryonic germ layers, and cytological changes of the uterine epithelial cells leads to the supposition that a close relationship exists between embryonic and uterine development during early pregnancy. The results of in-vitro studies of embryonic development and of experiments concerning asynchrony between embryos and uterine environment conf...

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...

Keywords: prolactin; ovarian function; luteal cells; steroidogenesis; pig© 1990 Journals of Reproduction & Fertility 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 ...

Oocytes secrete factors that control cumulus and granulosa functions, including cumulus expansion and steroid hormone production. Some members of the transforming growth factor ß (TGFß) superfamily influence these activities, yet it is still not determined conclusively whether any of these superfamily members are the previously reported oocyte-secreted factors. The aim of this study was to examine the effects of TGFß1 and growth differentiation factor 9 (GDF-9) ...

Abstract unavailable© 1987 Journals of Reproduction & Fertility Ltd...

Keywords: pig; models; metabolism© 1990 Journals of Reproduction & Fertility Ltd...