Bioscientifica Proceedings

Summary. Synthesis of biologically active LH is complex, due in part to its hetero-dimeric subunit structure and to the numerous post-translation modifications of each subunit. Through the use of mammalian expression vectors we have been able to introduce the bovine α subunit and LH-β genes into a Chinese hamster ovary cell line deficient in dihydrofolate reductase. The bovine genes are actively expressed and the Chinese hamster ovary cells secrete b...

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 ...

Keywords: oocyte; maturation; meiosis; differentiation; fertilization; pig© 1990 Journals of Reproduction & Fertility Ltd...

The pig industry is confronted with substantial losses due to piglet mortality. With 3-8% stillbirths and generally > 10% preweaning mortality, approximately one fifth of al I fetuses formed fully at the end of gestation die before weaning. Most of these losses occur in the perinatal period. Overall prenatal development (birth weight) and specific prenatal developmental and maturational processes in late gestation are predisposing factors for perinatal losses. Birth weight ...

There are many potential applications of transgenic methodologies for developing new and improved strains of livestock. One practical application of transgenic technology in pig production is to improve milk production or composition. The first week after parturition is the period of greatest loss for pig producers, with highest morbidity and mortality attributed to malnutrition and scours. Despite the benefits to be gained by improving lactation performance, little prog...

In vitro production (IVP) including in vitro maturation (IVM) and fertilization (IVF) is now an important technology for obtaining live piglets. However, there are still two significant obstacles to the efficient production of viable porcine embryos: (1) polyspermy and (2) fertilization of oocytes arrested at the immature stage. These phenomena relate to production of embryos with abnormal ploidy (polyploidy). To avoid these problems, careful selection of mature oocytes ...

Unlike in sheep, in which immunization against androstenedione causes mild and reasonably controlled increased ovulation rate, in similar studies cattle showed highly variable responses ranging from increased ovulation rate and fertility through to anovulation/anoestrus or superovulation. As a consequence, interest in manipulation of ovulation rate through this approach has declined and is now focused on immunological manipulation of endogenous inhibin following successful stu...

Declining fertility is a major problem for the dairy industry. Recent developments of Omics-technologies facilitate a comprehensive analysis of molecular patters in gametes, embryos and tissues of the reproductive tract which may help to identify the reasons for impaired fertility. Large Omics-datasets require appropriate bioinformatics analysis in the context of rapidly expanding and evolving scientific databases. This overview summarizes the current status of ruminant genome...