Bioscientifica Proceedings

Fertilization of the egg, or oocyte, initiates the entire developmental process, but while the mechanism by which the spermatozoa triggers the oocyte to resume meiosis has been studied extensively, conclusions about this process are still elusive. Some workers have suggested that a molecule on the surface of the spermatozoon may interact with a receptor on the plasma membrane of the oocyte, thereby triggering the oocyte to resume meiosis. Other workers have focused on a ...

Considerable progress has been made in the in vitro production of pig embryos using improved methods for in vitro maturation (IVM) and fertilization (IVF). Despite the progress, polyspermic penetration remains a problem for in vitro-matured oocytes. Variation among boars, ejaculates and IVF protocols used in different laboratories appears to influence the incidence of polyspermy. Recent studies indicate that oviduct cells and their secretions p...

Great advancements in cryopreservation of pig embryos have been made since the last International Conference on Pig Reproduction (ICPR). In 1997, there were standard methods to cryopreserve germplasm and embryos of most livestock species, except for the pig, and development of this technology for use in the international pig industry was slow and in the early stages. Since 1997, there have been advancements in cryopreservation of pig embryos, with reports of production o...

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

Summary. Evidence is presented for the involvement of a number of specific uterineand conceptus-derived proteins in endometrial differentiation and conceptus or feml development. These secretory proteins include mitogens (insulin-like growth factor-I and -II, epidermal growth factor, uterine lumina] fluid mitogen). binding and transport proteins (uteroferrin, insulin-like growth factor and retinal binding proteins, respectively), protease inhibitors (anti...

The occurrence of puberty in the female is due to the interplay of central and peripheral mechanisms in which the hypothalamic-pituitary-ovarian axis regulates growth and gonadal function, as well as adipocyte hormone secretion. Hypothalamic GnRH mRNA expression increased at 3.5 months of age and declined by 6 months of age. Concomitant with the age related reduction in the oestrogen negative feedback on LH secretion was a decline in hypothalamic oestrogen receptor-&alph...

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

Summary. Tests for the detection of pregnancy early after insemination have not yet reached their full potential. Currently, the milk progesterone assay provides the earliest possible test, at an interval of one oestrous cycle after insemination, i.e. 17, 21 and 21 days in sheep, goats and cows respectively. This assay is pregnancy non-specific and rate of detection of pregnant animals is acceptable but less than desirable.Detection of a...

Keywords: lactation; weaning; sow; endocrinology; suckling© 1990 Journals of Reproduction & Fertility Ltd...

In some situations, the pig has advantages over the mouse as a model in biomedical research. The availability of pluripotent cell lines is likely to broaden this appeal. Here we review progress in the derivation and characterization of embryonic stem cells (ESC) and induced pluripotent lines (iPSC) from pigs. Until recently, most porcine ESC failed to meet the full criteria for pluripotency, but that may be changing as more becomes known about the culture conditions requ...