Bioscientifica Proceedings

The early morphological events in pig placental development are summarized and related to the known data on differences in placental vascular efficiency between Meishan and US breeds. The activation and localization of a number of factors, the ligands and their receptors, such as insulin-like growth factor (IGF), transforming growth factor β (TGFβ), platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF), as well as retinoids and cal...

Androgens have potential actions in almost all the organs of males and females. In females, most organs contain some tissues with cells that have androgen receptors. Androgens can regulate cellular functions by binding to androgen receptors or be converted to other hormones. For example, testosterone can bind to the androgen receptor or be aromatised to oestradiol. Treating animals with testosterone, therefore, might elicit some androgenic and oestrogenic effects. Altern...

In experimentally induced diapause model in mice, blastocysts remain dormant for an extended period but resume implantation competency upon estrogen injection. The underlying mechanism by which extended longevity of dormant blastocysts is maintained is unclear. We have previously shown that dormant blastocysts, during experimentally induced diapause, exhibit heightened autophagic activation. Activation of autophagy appears to be a crucial adaptive response for survival in the ...

The potential fertility of a sire can not be evaluated in the field simply by assessment of mating ability and physical examination, although these procedures can expose his limitations as a breeder. Finding a laboratory test that accurately estimates the potential fertility of a semen sample or a sire is also distant, as shown by the modest correlations that present tests have with fertility. Due to the complex nature of male fertility any sought for laboratory method must in...

Reproductive biology research on camelids offers some interesting peculiarities and challenges to scientists and animal production specialists. The objective of this paper is to review camelid reproduction, advances in reproductive physiology and reproductive biotechnologies in camelids and discuss some areas for further research. In the female, the focus has been on understanding follicular dynamics. This has allowed development of synchronization and superovulation strategie...

A series of integrated, effective techniques is required to produce pig embryos from follicular oocytes in vitro. The failure to form a male pronucleus and polyspermy have been serious problems in efforts to produce embryos efficiently in vitro from pig oocytes. The former problem is now considered to be due to oxidative stress and the latter has been partially solved by reducing the number of capacitated spermatozoa reaching the oocytes. By the use of n...

An overview is presented on the structure and function of the pig oviduct in relation to sperm capacitation and oocyte development in vivo. In pigs, a functional sperm reservoir is established in the uterotubal junction-isthmus when sperm deposition occurs before ovulation. Capacitation is assumed to occur in this location, and spermatozoa progress towards the ampullaryisthmic junction at about the time of ovulation as a consequence of capacitation and hyperacti...

Embryo technological procedures such as in vitro production and cloning by nuclear transfer are not as advanced in pigs as in cattle and cannot yet be applied under field conditions. The present paper focuses on genome activation in in vivo-derived, in vitro-produced and nuclear transfer pig embryos with special emphasis on the development of embryonic nucleoli, where the ribosomal RNA (rRNA) genes transcribed can be used as markers for genome ...

Trophoblast invasiveness in ruminants is limited to fusion of migrating binucleate cells with uterine epithelium, but considerable tissue remodelling and angiogenesis occurs within the endometrium at implantation. Such processes are elsewhere associated with an altered balance of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). ProMMPs-1, -2, -3 are secreted by cultured ovine endometrial stromal, but not epithelial, cells and expression of proMMP-1 and pro...

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