Bioscientifica Proceedings

The autocrine and paracrine role of the insulin-like growth factors (IGFs) and epiderrnal growth factor (EGF)-related peptides in pig ovary are reviewed. For convenience, each of these regulatory systems is divided into several interactive components: regulated expression of the growth factors, growth factor reception at the cell surface and intracellular action of the growth factors. In addition, the concept of regulated bioavailability and targeting of growth factors in...

limiting factor to realizing the full potential of many of the new reproductive techniques is the lack of ahundant numbers of fertilizable oocytes. This problem could he addressed by using the large source of oocytes available from preantral and primordial follicles by developing systems for in vitro growth. In vitro systems that use early growing follicles as a source of oocytes have been developed for laboratory species and these have been successful ...

Summary. The consideration of the fetus as a semi-allograft by virtue of its paternally inherited histocompatibility antigens is generally accepted. Many hypotheses have been put forward to explain the immunological acceptance of the conceptus by the maternal immune system, but no single theory has proved to be adequate. Most studies so far have been carried out with laboratory rodents and men but corresponding investigations of farm animals and especiall...

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 ...

In all vertebrate species studied, the main central population of GnRH neurones, which produces the final messages regulating reproduction, originates outside the brain. Early during fetal life, they appear in the olfactory placode epithelium and then migrate toward the base of the telencephalon in close association with the nervus terminalis, penetrate the brain within the nervus terminalis roots, reach their final locations and eventually grow axons toward their targets. Onl...

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

Implantation is a critical step in the progress of pregnancy, during which the conceptus acquires a fixed position within the uterine lumen, and leads to the establishment of the placental structures. This process implies some cellular modifications of both the uterine epithelium and the trophoblast to ensure cell adhesion between the two tissues. In ruminants, the implantation process is characterized by three main steps: a long pre-attachment period lasting 2–3 weeks d...

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...