Bioscientifica Proceedings

High numbers of lipid droplets (LDs) in mammalian eggs are stored and maintained throughout embryo development without marked signs of their utilization. It was previously demonstrated in large domestic mammals that removing lipids from the zygote does not influence post-implantation development in terms of the rate of delivered offspring. Previously studied pig and cow eggs contain considerable amounts of LDs, while mice have a very low level of ooplasmic lipids, which allows...

Abstract unavailable© 2009 Society for Reproduction and Fertility...

Abstract unavailable© 1982 The authors...

Seminal plasma proteins participate in a number of events important for fertilization and the establishment of pregnancy. As a result, attempts have been made to use them to enhance reproductive performance associated with several swine reproductive technologies. Inclusion of seminal plasma into cryopreservation and sex-sorting protocols improved sperm viability and membrane integrity and suppressed capacitation-like changes which are considered to be major challenges as...

Summary. Declining fertility and perturbations in reproductive development in a variety of species have been linked to exposure to endocrine disrupting chemicals (EDCs), which are ubiquitous in the environment. Ruminants are largely exposed to such chemicals in sewage sludge fertiliser widely used in animal production systems. This has been investigated experimentally through the deliberate exposure of pregnant ewes to sewage sludge fertilised pastures or cont...

In addition to endocrine regulation by the gonadotrophic hormones, the functions of the testes are regulated locally by paracrine and autocrine factors. Some attempts have been made to isolate cells from the testes of immature bulls and rams for investigation of cell function in vitro. However, most studies have used in vitro cultures of cells isolated from the testes of rats and a large variety of factors have been identified as potential local regulators. T...

Summary. Changes in uterine blood flow throughout pregnancy appear to be due to steroid-induced alterations in uterine arterial tone and contractility. Arterial contractility is a transient reduction in luminal diameter in response to nerve stimulation or to an alpha-1 adrenergic agonist, leading to short-term reduction in uterine blood flow. Tone is the pressure exerted by an arterial segment against an intraluminal flow (distensibility) and is considere...

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...

Blastocyst activation, referring to the blastocyst acquiring the implantation competency, is the determining factor for implantation into the receptive uterus. It involves the process of embryonic cell differentiation to contact and initiate dialog with the uterine cells. Before the application of -omics approaches to this biological event, only the cellular morphological changes and a small number of molecules were known to regulate this process. This review aims to discuss t...

It has been suggested that the long-term reproduction of the sow is best served by minimizing weight and fat loss in lactation. Such a strategy would require only a minimal restoration of weight in the following pregnancy, which would be beneficial, since the greater feed intake and weight gain in pregnancy, the greater the weight loss in lactation. Feeding ad libitum should be practised during lactation while gestation feed intake must be held low. A relationship between...