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Showing papers in "Theriogenology in 1996"


Journal ArticleDOI
TL;DR: Before transgenic farm animals become a common component of the livestock production industry, a number of formidable hurdles must be overcome.

413 citations


Journal ArticleDOI
TL;DR: The production of large offspring after embryo manipulation casts new perspectives on the roles of reproductive technology in both livestock and human reproduction and an understanding of the underlying cellular mechanisms should lead to improved procedures for the handling and manipulation of embryos.

380 citations


Journal ArticleDOI
TL;DR: 40 Brangus calves from embryos cloned by a nuclear transfer technique were delivered by caesarean section during naturally initiated parturition to maximize survival rates when life-threatening physiologic abnormalities were recognized.

184 citations


Journal ArticleDOI
TL;DR: It was determined that bovine oocytes continue growing in all follicular sizes studied, including >1- to 15-mm follicles, and oocytes which extruded polar bodies at an earlier time during maturation were, on average, larger than those which extruding polar bodies later.

179 citations


Journal ArticleDOI
TL;DR: Results indicate that proliferation of granulosa cells of bovine preantral follicles can be stimulated by bFGF, FSH and EGF, whereas TGFbeta inhibits growth, and that they are steroidogenically active in culture.

176 citations


Journal ArticleDOI
TL;DR: The morphological characteristics of the bovine luteal cells are the focus of this review, believed to reflect a change in progesterone and protein secretion that will eventually influence a successful pregnancy or another ovulation if pregnancy fails.

160 citations


Journal ArticleDOI
TL;DR: It is concluded that the individual composition of seminal plasma affects the suitability of stallions for semen cryopreservation by influencing the resistance of spermatozoa to the freezing and thawing process.

152 citations


Journal ArticleDOI
TL;DR: The current progress in embryo cryopreservation is discussed, and intracellular damage to the cytoarchitecture ofcryopreserved embryos is addressed and attempts to detour this damage by utilizing cytoskeletal stabilization prior to cryop Reservation.

147 citations


Journal ArticleDOI
TL;DR: Differences in concentrations of follicular fluid estradiol, but not numbers of granulosa cell gonadotropin receptors, were associated with the early growth divergence of dominant and subordinate follicles and the eventual growth termination of the dominant follicle (Day 10).

132 citations


Journal ArticleDOI
TL;DR: Semen quality was poorest in stallions under 3 yr of age and over 11 yr, and significant breed variation was apparent in most characteristics except for pH, semen color, abnormal midpieces and urethral pulsations.

119 citations


Journal ArticleDOI
TL;DR: It is concluded that testis echogenicity increased during the most active phase of growth of the seminiferous tubules as more mature germ cells were produced and testosterone secretion rose markedly with the production of mature spermatozoa.


Journal ArticleDOI
TL;DR: Although the incidence of fetal loss was low, there was an unacceptable high perinatal mortality of the calves, which seems to indicate that a proportion of in vitro produced calves may suffer from factors inherent in the in vitro production system.

Journal ArticleDOI
TL;DR: It was found that large term fetuses appear to predispose a cow to uterine torsion, and Brown Swiss cows were at a significantly higher risk than Hereford, Angus, and Jersey cows when compared with Holstein-Friesian cows, the largest breed population.

Journal ArticleDOI
TL;DR: The purpose of this paper is to review the mechansims responsible for controlling the endocrine function of this tissue in the bovine ovary.

Journal ArticleDOI
Jeremy G. Thompson1
TL;DR: Perfusion culture of embryos offers a number of advantages over static conditions and it is proposed that such systems will become increasingly popular in the future.

Journal ArticleDOI
TL;DR: How close the authors are to achieving ‘oocyte farming’ for domestic species is discussed and the latest developments in these techniques are highlighted.

Journal ArticleDOI
TL;DR: Pluripotent stem cells will become valuable after demonstration of germ line transmission resulting in a full term live calf, and several approaches to overcome this problem are described.

Journal ArticleDOI
TL;DR: It is suggested that prediction of sperm production may be dependent on factors other than SC, testicular volume, or weight, as well as testicular shape in mature Holstein bulls.

Journal ArticleDOI
TL;DR: It appears that compensatory thermoregulatory mechanisms restored SST but were not able to restore SQT and ITT, and the importance of theScrotal neck in scrotal/testicular thermoreGulation is emphasized.

Journal ArticleDOI
L.J. Pérez1, A. Valcárcel1, M.A. de las Heras1, D.F. Moses1, H. Baldassarre1 
TL;DR: It is suggested that freezing and thawing of ram spermatozoa provoke structural and/or functional alterations that result in an increased proneness to capacitation and acrosome reaction, a fact to be kept in mind for the timing of both in vivo and in vitro fertilizing procedures.

Journal ArticleDOI
TL;DR: CIDR devices used in conjunction with PGF(2alpha) effectively synchronize estrus in dairy heifers, leading to an increase in the pregnancy rate to first insemination in the control and resynchronized groups.

Journal ArticleDOI
TL;DR: With the in vitro procedures described here, the technology was able to produce normal embryos from more than half of the treated ewes, indicating that the technology is useful for the multiplication of genetically valuable animals affected by temporary or irreversible infertility.

Journal ArticleDOI
TL;DR: The development of ultrasound guided methods for the recovery of oocytes from calves greater than five months old and their improved developmental capacity as demonstrated by development to blastocysts and birth of live calves indicates that the prepuberal calf will play a significant role in animal breeding programs of the future by serving as sire dams or by expanding the influence of genetically superior animals in producer herds.

Journal ArticleDOI
TL;DR: The results suggest that although superovulation increases follicular size and decreases atresia, these conditions are not sufficient to confer developmental competence on the oocytes.

Journal ArticleDOI
TL;DR: Retrospective study indicated that the future dominant follicle could have been collected for experimental purposes with a 100% success rate if the following criteria had been used: 1) diameter of largest follicle 10 mm (largest follicle taken), 8 mm (2 largest follicles taken), or 7 mm (3 largest foll Balls taken); 2) diameter difference between the 2largest follicles of 4 mm, 3 mm, or 2 mm, which would have helped to synchronize follicular wave emergence.

Journal ArticleDOI
P.E.J. Bols1, A. Van Soom1, M.T. Ysebaert1, J.M.M. Vandenheede1, A. de Kruif1 
TL;DR: The effects of aspiration vacuum and needle diameter on the morphology of the cumulusoocyte-complex (COC) and developmental capacity of the oocyte after IVF was studied in 2 experiments using a disposable ovum pick-up needle guidance system.

Journal ArticleDOI
TL;DR: The glutathione synthesis promoter 2-ME exerts its embryotropic role on the development before the fourth cleavage, thus yielding an improvement in blastocyst formation, and intracytoplasmic glutATHione concentration of bovine embryos derived from in vitro-culture increases during preimplantation development.

Journal ArticleDOI
TL;DR: A model utilizing data from flow cytometric analyses, the percentage of motile spermatozoa, and hamster oocyte penetration was highly correlated with stallion fertility.

Journal ArticleDOI
TL;DR: Radioimmunoassay (RIA) was used to measure plasma eCG binding in dairy goats at the beginning of a progestagen/eCG treatment and 25 d after eCG administration and increased with the number of treatments they had previously received.