Bioscientifica Proceedings

Abstract unavailable© 2013 Context Products Ltd...

A successful mating involves the coordination of many physiological events including insemination, gamete transport and ovulation. As more basic information about these processes becomes available, it is apparent that there are opportunities for manipulating these physiological events and enhancing the reproductive success of natural and artificial matings. The primary intent of this review is to examine the effectiveness of several of these strategies, as determined by t...

The formation, normal function and destruction of corpora lutea are essential features of normal reproduction. Although the formation of corpora lutea from follicles is largely dependent on pituitary gonadotrophins, the process of luteolysis is locally regulated and poorly understood. The corpus luteum consists of several steroidogenic and nonsteroidogenic cell types that interact with each other in a paracrine manner. Under cell culture conditions, large luteal cells tha...

© 1985 Journals of Reproduction & Fertility Ltd...

Summary. Within 14 h of ovulation, follicular development in gilts was skewed towards a majority of mature follicles, based on their endocrine milieu. Oocyte maturation was also skewed, with a majority of the oocytes being meiotically more developed than the rest. Similarly, the pattern of ovulation in gilts was such that 70% of the follicles ovulated during a short period of time, while most of the remaining 30% ovulated over a more protracted period. Th...

Summary. Results of a detailed study involving 18 pregnant, 17 cyclic and 12 inseminated but non-pregnant Holstein heifers indicated the following. (1) Jugular plasma progesterone concentrations were higher (P < 0.05) in pregnant than in cyclic or in inseminated–non-pregnant animals from Days 10 through 18. (2) Jugular plasma progesterone concentrations of inseminated–non-pregnant animals could be related to heifers in which (a) fertiliz...

Neuropeptides and catecholamines are biologically active substances which play the roles of neurotransmitters, neuromodulators and cotransmitters in the central nervous system (CNS). These substances are known to regulate and influence a wide spectrum of functions; such as food and water intake, thermoregulation, growth and maturation, sexual behaviour, reproduction, function of the hypothalamic-hypophysial-organ axes, and many others. This large family of neuropeptides ...

Consistent production of large quantities of fertile semen is a primary concern of boar management programmes. Common visual tests such as motility are poor indicators of the fertilizing capacity of an ejaculate. Research studies have demonstrated that, in general, if motility is 60% or greater, there are no relationships among the percentage of motile spermatozoa, in vitro sperm penetration rates, farrowing rates and litter size. Biological and environmental fac...

The functions necessary for normal fertilization to occur in vivo or in vitro are examined and a rational approach to identifying the main features of a fertilizing spermatozoon are developed. It is concluded that methods for testing the quality of spermatozoa must probe the dynamic changes experienced by the spermatozoa during capacitation or under stressful incubation conditions. Recent developments in the multiva hate analysis of sperm motility data a...

Abstract unavailableKeywords: gene transfer; zygotes; cattle© 1991 Journals of Reproduction & Fertility Ltd...