Bioscientifica Proceedings

Abstract unavailable© 2013 Context Products Ltd...

Summary. In Exp. 1, sheep fetuses (2 male and 3 female) were gonadectomized between Days 70 and 120 of gestation and their blood LH and FSH levels were compared to those of control animals (4 male, 6 female) at regular times during the first year after birth. In Exp. 2. fetuses (3 male and 5 female) were gonadectomized between Days 50 and 60 of gestation and gonadotrophin levels at Day 90 of gestation were compared to those of control fetuses of the same age. ...

Summary. The relationship between the pituitary gland and testis in rams was studied from birth to sexual maturity. The concentrations of LH, FSH and testosterone increased between 5 and 7 weeks of age; the rise was not correlated with any specific cytological change in the testis. An augmented pituitary response to LH-RH was demonstrated as levels of gonadotrophin increased. It is unclear whether this change in sensitivity plays a role in initiation of the pu...

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 ...

Although mouse embryonic stem cells have been used widely for over a decade as an important tool for introducing precise genetic modification into the genome, demonstrating the great value of this technology in a range of biomedical applications, similar technology does not exist for domestic animals. However, the development of somatic cell nuclear transfer has bypassed the need for embryonic stem cells from livestock. The production of offspring from differentiated cel...

Transplantation of germ cells from fertile donor mice to the testes of infertile recipient mice results in donor-derived spermatogenesis and transmission of the donor haplotype to offspring of recipient animals. In the pig, germ cells can be transplanted to a recipient testis by ultrasoundguided cannulation of the rete testis with delivery of cells by gravity flow. It is important to note that germ cell transplantation was successful between unrelated, immuno-competent p...

Abstract unavailableKeywords: gene transfer; gene modification; gene expression; livestock; transgenic animal© 1991 Journals of Reproduction & Fertility Ltd...

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

The extensive use of embryo technologies has emphasized the need for assessing embryo quality by morphological techniques, such as transmission electron microscopy, immunocytochemistry for confocal laser scanning microscopy and fluorescence in situ hybridization. By a combination of these techniques, it has been possible to demonstrate: (i) that rRNA gene activation, as monitored by embryonic nucleolar development, is comparable in bovine embryos developed in vivo...

Abstract unavailable© 1995 Journals of Reproduction and Fertility Ltd ...