Bioscientifica Proceedings

Summary. Nuclear transfer for the study of differentiation in amphibians has been used since the 1950s, but not until recently have the same procedures been applied successfully to some mammals. Nuclear transfer, as developed for the amphibian, is successful in sheep, cattle, rabbit, and pig, but not mouse embryos. This fact is discussed in relation to the species-specific timing of the activation of the zygotic genome. Nuclear transfer to an oocyte presu...

Summary. Behavioural responses can have direct effects on reproduction when the performance of the behaviour contributes to productivity (e.g. achievement of copulation). Alternatively, there are indirect effects where a behavioural change is insufficient to allow adaptation to an environmental change and so the animal has to resort to physiological mechanisms with potential adverse effects on productivity.Boar contact has substantial ...

The uterus plays a central role in the reproductive biology of mammals. Adaptation of the uterus from an oviparous to a viviparous nature required changes that involved production of a uterine environment that could support the development of the embryo and fetus. Production of a suitable environment includes the synthesis and secretion of products by the uterine endometrium. However, the uterine endometrium is not a single homogeneous unit, but rather consists of several...

Geneticists have made limited progress in improving reproductive traits in pigs through traditional selection and crossbreeding systems. Recent advances in molecular genetics and the human genome project have allowed progress in gene identification and gene mapping in pigs. The pig genetic linkage map now has over 1700 genetic markers, and about 200 of these are genes. Furthermore, comparative genomic maps are improving and are becoming useful tools. Molecular approaches ...

Abstract unavailable© 2013 Context Products Ltd...

Abstract unavailable© 2013 Context Products Ltd...

The Meishan pig provides a biological model with the genetic capacity to express a high prolificacy. This prolificacy can be partially attributed to a higher ovulation rate and a higher rate of prenatal survival at a given ovulation rate throughout gestation than in European breeds. Both early embryonic survival (factors inherent to the ovum and uterus, which occur before day 25 of gestation) and uterine capacity (factors inherent to uterine limitation, which occur from 3...

A review of the remarkable production of steroids by the testes of the boar is presented, with the principal aims of highlighting the achievements of the Leydig cells and, at the same time, pointing to the considerable deficiencies in our understanding of its biological relevance. The onset of gonadal steroidogenesis at an early stage of sex differentiation and the pattern of pre- and postnatal secretion of steroids are outlined. This is followed by a list of steroids id...

Determining the stage- and tissue-specific patterns of gene expression shown by the embryo and fetus will provide information about the control of normal development. Identification of alterations in these patterns associated with specific abnormal phenotypes will also be informative regarding the underlying molecular mechanisms. In addition, qualitative and quantitative changes in gene expression that deviate from the norm may provide a potential marker system for predicting ...

While the role of oestradiol and progesterone in the control of GnRH pulsatile secretion and generation of the preovulatory GnRH surge to induce release of the LH surge has been fully investigated, less attention has been given to changes in the pituitary gland that may sensitize gonadotrophs to switch from pulsatile release to surge release of LH, in particular. Furthermore, in the follicular phase while pulsatile secretion of LH is maximal, FSH secretion is reduced, yet both...