Showing papers in "Theriogenology in 1992"

TL;DR: It is demonstrated that a semi-chemically defined medium can successfully support the development of bovine embryos to the morula stage to a limited extent, but the medium lacks some nutrients or growth factors to fully support development through the blastocyst stage.

TL;DR: In this paper, the complexity of the sperm plasma membrane and the many steps in a cryopreservation procedure where membrane perturbations can occur are described, and an attempt has been made to describe the complexities of the SPM and its interaction with its components.

TL;DR: Evidence indicates that embryos are relatively insensitive to changes in the composition of media and that zygotes can develop to blastocysts at rates equal to or higher than those obtained in vivo, however, in vitro culture is associated with several developmental abnormalities.

TL;DR: An understanding of the mechanisms of production and elimination of oxygen radicals in embryos may lead to significant improvements in the success of embryo culture and the practical techniques which depend on it.

TL;DR: The ability to support development of IVM/IVF embryos to the morula and blastocyst stages in defined media without serum or somatic cell conditioning will help to elucidate the metabolic and nutritional requirements of bovine oocytes and embryos, and to formulated improved culture media.

TL;DR: The ability to cryopreserve mammalian oocytes effectively would greatly increase their availability for a broad range of reproductive technologies, and estimates of biophysical parameters which influence the osmotic and cryobiological responses of oocytes are becoming available and may be useful for developing freezing protocols.

TL;DR: It is indicated that developmentally capable bovine embryos reach the 2- cell stage at 36 hours post insemination, and that they become compacted at the 32-cell stage, which usually occurs between 126 and 138 hours post Insemination.

TL;DR: The ability to produce embryos from oocytes recovered from newborn or prepubertal calves offers the potential for markedly reducing the generation interval in cattle, thereby substantially accelerating the rate of genetic gain that can be achieved through embryo transfer.

TL;DR: The results confirmed previous reports that old age was associated with increased endometrial inflammation, reduced pregnancy rate and increased embryo-loss rate and indicated that uterine contractility and uterine tone were reduced and the fixation of the embryonic vesicle occurred later in old than in young mares.

TL;DR: Embryonic diversity was not related to the duration of ovulation, neither at the level of ovary nor of sow, and transrectal ultrasonography was found to be an appropriate nonsurgical method of studying the durationof ovulation in pigs.

TL;DR: Experiments were conducted to determine temperatures between 24 and 4 degrees C at which stallion spermatozoa are most susceptible to cold shock damage, and total and progressive motility was evaluated by computerized semen analysis initially and after 6, 12, 24, 36 and 48 hours of cooling.

TL;DR: Artificial insemination has allowed rapid genetic progress in dairy cattle through the use of semen from genetically superior sires but the need for accurate detection of estrus has not been eliminated.

TL;DR: In this paper, the concentration of seminal plasma required for the preservation of sperm motility was determined, and the addition of egg yolk to a milk-based semen extender improved the maintenance of motility.

TL;DR: Embryos frozen in ethylene glycol can be rehydrated directly in holding medium without step-wise dilution of the cryoprotectant yielding viability equivalent to that of embryos frozen in glycerol and rehydrating in a step- wise manner.

TL;DR: The results suggest that the presence of a dominant follicle at the time of gonadotrophic stimulation decreases the superovulatory response, however, more precise criteria for determining follicular dominance are required in order to improve the predictability of embryo yield in future.

TL;DR: Embryo technologies have not as yet contributed to practical conservation of rare wildlife species, but if reality-based conservation is defined as a continual data-gathering process that assimilates any and all information ultimately useful for preserving species, then embryo technologies are making considerable contributions to conservation biology.

TL;DR: The experiments demonstrate the potential for using ethylene glycol as a cryoprotectant for bovine embryos, thus permitting direct transfer of frozen-thawed embryos to recipient females.

TL;DR: These experiments show that the critical effect of oxygen concentration on embryo development in vitro and the ability of embryos produced by in vitro procedures to survive freezing can be influenced by the type of culture system employed.

TL;DR: First calf heifers and second and third parity cows as well as fourth parity and higher cows demonstrated the highest overall performance in all the parameters tested when they expelled their placentas within 6 hours after parturition.

TL;DR: All the reports to date concerning the pathological conditions in the organs integrating the hypothalamic-hypophyseal-gonadal axis in ruminants with cystic follicles as well as the causative factors associated with the disease are reviewed, emphasizing the role of uterine infections and stress.

TL;DR: Modifications to simple culture media have demonstrated that glutamine can serve as the sole exogenous energy source for development from the zygote to the blastocyst stage in vitro and Glucose was not inhibitory to the development of pig embryos in vitro.

TL;DR: Results indicate that slow dilution after thawing prevents the sharp change in osmolarity and viscosity between the cryopreservation solution and diluent, and protects the fertilizing capacity of frozen-thawed mouse spermatozoa.

TL;DR: The results confirmed that after supplementation of in-vitro maturation media with IGF-I, 52, 49 and 51% of the cumulus-oocyte complexes in Groups I, III and V did not show cumulus expansion, whereas in Group VI (control) only 1% did not expand.

TL;DR: Nine of 88 inseminated oocytes developed to the blastocyst stage and three blastocysts were transferred to 3 recipients, resulting in 2 pregnancies.

TL;DR: Follicular cumulus-enclosed goat oocytes were matured in vitro in the presence of granulosa cells, follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol-17beta, andPolyspermy was the main abnormality detected and it affected almost 20% of the inseminated oocytes.

TL;DR: Data indicate that restricted feed intake in goats tended to delay the onset of estrus and lowered the ovulation rate, incidence of multiple ovulations, and pregnancy rate.

TL;DR: Increasing the number of buserelin injections enhanced the precision of estrus, but not the conception rate, without any detrimental effect on luteal activity and induced more estruses in postpartum acyclic beef cattle.

TL;DR: It was concluded that postweaning nutrition management had a strong influence on lamb weight gain, which in turn was related to testicular growth and puberty onset in Menz ram lambs.

TL;DR: The effect of each part of the follicle on meiotic resumption in bovine oocytes is summarized and Associations between mural granulosa cells and cumulus cells seem to be essential for prevention of nuclear maturation but the health ofthe follicle and the follicular fluid content are also important.