Journal of reproduction and fertility 

About: Journal of reproduction and fertility is an academic journal. The journal publishes majorly in the area(s): Ovulation & Pregnancy. It has an ISSN identifier of 0022-4251. Over the lifetime, 1432 publications have been published receiving 51979 citations.

Culture of pig embryos

Abstract: Pig embryos can be cultured using a number of different strategies including complex approaches like culture in vivo in a surrogate oviduct (rabbit, sheep, mouse), culture in mouse oviducts in organ culture, and co-culture of embryos with cells in addition to simple approaches like culture in defined media or salt solutions. Addition of serum to medium has been of particular importance where blastocyst development and hatching are required. Pig conceptuses (day 10-15), embryonic discs or cell lines derived from conceptuses can be cultured in complex media like Eagle's minimal essential medium or Dulbecco's modified Eagle's medium with serum, although embryonic discs can be cultured in the absence of serum. In contrast, early stage pig embryos (one-cell to blastocyst) are best cultured in simpler media such as those used for mouse embryos. The media that have been used are all relatively similar in composition. They contain salts and one or more energy sources such as glucose, lactate, or pyruvate with BSA as a macromolecular component. Early attempts to culture pig embryos were not very successful, but some embryos did develop to the blastocyst stage. More recent reports indicate a much higher rate of development with relatively little or no change in media composition. Some workers have reported improved development in medium lacking glucose, which is consistent with findings with laboratory animals such as hamsters. Glutamine can serve as the sole exogenous energy source in medium lacking glucose, lactate and pyruvate. Addition of taurine and hypotaurine to culture medium enhances development of pig embryos in vitro. We suggest, where possible, adoption of a standard medium that could be used by different laboratories and, perhaps, with different species. Use of one medium for different species would simplify experimental protocols, enhance studies of comparative embryonic physiology and metabolism, and expedite transfer of information obtained in different species.

Effects of energy balance on follicular development and first ovulation in postpartum dairy cows.

Abstract: As milk production has increased during the past four decades, conception rates in lactating cows have declined. Although reduced reproductive performance has been associated with high milk yields, measures of postpartum ovarian activity have been more closely related to energy balance. The relationship between daily energy balance and postpartum reproductive activity is confirmed by longer intervals to first ovulation in cows with greater body condition loss. Patterns in daily energy balance, such as improvement from nadir, have been correlated with enhanced follicular function and a shorter interval to first ovulation. Such observations are consistent with increased LH pulse frequency following the energy balance nadir in lactating dairy cows. Evidence indicates a primarily hypothalamic locus for the modulation of LH secretion during negative energy balance. Formation of follicular waves after parturition begins synchronously in response to increased FSH in the first week postpartum, and is typically not a limiting factor in reproductive recrudescence. Altered follicular responsiveness to gonadotrophic support through changes in metabolic hormones such as insulin-like growth factor I (IGF-I) and insulin may contribute to impaired function of dominant follicles early postpartum. Positive relationships between changes in energy balance, peripheral IGF-I and function of dominant follicles support the identification of IGF-I and the day of the energy balance nadir as metabolic modulators of postpartum ovarian activity in dairy cows.

Biology and endocrinology of ovulation, pregnancy and parturition in the dog.

Abstract: There is considerable variation among bitches in commonly encountered intervals between cycles (5-12 months), durations of anoestrus (1-8 months), durations of follicular phase pro-oestrus (3-21 days) and periovulatory oestrous behavior (3-21 days), intervals from preovulatory LH surge to oestrus onset (-2 to 5 days), and intervals from fertile mating to parturition (57-68 days) The extent of variation within bitches ranges from slight to great However, there appears to be very little variation in the intervals from LH surge to ovulation (2 days), to post-ovulatory oocyte maturation (approximately 4 days), to implantation (approximately 18 days), to selected developmental stages of pregnancy, or to parturition (64-66 days) There are no tests diagnostic of early pregnancy The onset times of persistent pregnancy-specific changes have been estimated, including radio-opaque fetal details (Day 46), elevated blood prolactin values (Day 35), elevated blood relaxin values (Day 25), echogenic heart beats (Day 24) and embryonic vesicles (Day 19), and potentially palpable uterine enlargements (Day 21) As in humans, there is an anaemia of pregnancy involving a 30% reduction in haematocrit and an increased incidence of insulin resistance during the second half of gestation Ovarian progesterone is required throughout pregnancy LH and prolactin are luteotrophic in the pregnant bitch as well as during the 2-month luteal phase of the non-pregnant bitch Parturition follows a luteolysis which occurs during an increase in prostaglandin F-2 alpha that begins 36 h pre partum Factors regulating the duration of anoestrus are not known but termination of anoestrus is associated with increased pulsatile secretion of LH