Bioscientifica Proceedings

On the basis of established surgical procedures for embryo recovery and transfer, the early pig embryo can be subjected to various manipulations aimed at a longterm preservation of genetic material, the generation of identical multiplets, the early determination of sex or the alteration of the genetic make-up. Most of these procedures are still at an experimental stage and despite recent considerable progress are far from practical application. Normal piglets have been ob...

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 ...

Pigs have a long standing and very successful history as biomedical model for studying human diseases and developing novel therapies mainly attributed to the many genetic, anatomical and physiological similarities with humans. Non-transgenic pig models have long been used for a wide range of human organ systems and diseases, and even complex metabolic disorders and have served as model for developing novel surgical techniques and endoscopic approaches, such as NOTES (nat...

Summary. Injection of prostaglandin (PG) F-2ct or its analogues has provided a . technique to induce parturition after Day 110 of gestation in the sow. The mean interval from PG injection to parturition ranges from 24 to 28 h, but only 50-60% of the sows farrow during an 8-10 h working day, and as many as 20% of sows may begin parturition before the injection of PG or > 22 h after the injection. The duration of parturition is positively associated with...

Transport of post-partum cows or sheep before an oestradiol-induced LH surge delayed gonadotrophin secretion possibly by affecting hypothalamic activity but not via an opioid mediated mechanism as the effect could not be reversed by naloxone. In addition, reduced LH responses to GnRH were observed in cattle during transport. In sheep, adrenocorticotrophic hormone (ACTH) also diminished the LH response to GnRH, but only when GnRH was administered 3 h after ACTH, not after 0.5 h...

For successful conception, fertilization-competent spermatozoa must be present at the site of fertilization in adequate numbers until ovulation has taken place. In pigs, a large volume of semen is delivered into the uterus. Most, if not all, of the inseminated liquid is voided from the vulva within a few hours after insemination and approximately 45% of the spermatozoa are lost. Large numbers of spermatozoa are also lost due to phagocytosis by polymorphonuclear leukocyte...

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...

Summary. In four studies secretion patterns of LH, FSH, prolactin, testosterone and progesterone were measured in male and female cattle to determine endocrine changes associated with sexual maturation. Two periods of increasing gonadotrophin secretion were observed, the second one coinciding with puberty. A short luteal phase of 8–12 days precedes the first oestrus at 10–11 or 14 months of age. The testosterone values of the bulls increased with age...

In sows, follicular development is inhibited during lactation, and weaning the piglets allows recruitment and selection of follicles that will undergo preovulatory maturation and ovulate. Lactation inhibits GnRH secretion, and in turn LH secretion, through neuroendocrine stimuli induced by suckling. Pituitary response to GnRH and the sensitivity of the hypothalamo-pituitary unit to oestradiol positive feedback are also reduced. The impact of lactation on the reproductive...

The ovine conceptus releases interferon-τ (IFNT), which prevents upregulation of the endometrial estrogen receptor (ESR1) and, consequently, oxytocin receptor (OXTR), thereby disrupting pulsatile release of prostaglandin F2α (PGF) in response to oxytocin. IFNT, through paracrine action on the endometrium, protects the corpus luteum (CL) during maternal recognition of pregnancy. Pregnancy also induces IFN stimulated genes (ISGs) in peripheral blood mononuclear cells (...