Reproduction, Fertility and Development
Number 3 2012
Early pregnancy and embryonic loss have been studied in mares treated with a prostaglandin to stop progesterone production. Treatment on or before Day 16 had minimal effects on the conceptus (the embryo and its membranes) whereas treatment on Day 18 usually led to abortion and/or conceptus degeneration within 3 days, thereby providing a predictable system in which to investigate molecular changes underlying pregnancy failure.
Cytochrome P450 (CYP) enzymes are important for drug metabolism, but there is limited information on their development in the fetus and newborn. Their levels in sheep liver were low in the fetus, increased after birth and fetal administration of cortisol increased their levels, particularly of CYP2D6. We conclude that drug metabolism in the fetus is limited by the low CYP expression and that the prepartum fetal cortisol rise may stimulate their expression.
The existence of additive genetic variation in secondary sex ratio is questionable in dairy cattle and there were no reports on the study of the genetic trend of sex ratio in dairy cattle. The aims of this study were to estimate variance components and genetic trends for secondary sex ratio in Iranian Holsteins. Exploitable genetic variation in secondary sex ratio can take advantage of sexual dimorphism for economically important traits, which may facilitate greater selection intensity and thus greater response to selection, as well as reducing the replacement costs.
Blastocyst hatching is an important developmental process for successful implantation. The present study reveals that supplementation of a chemically defined protein-free medium with glucose and glycine synergistically improves the viability and hatching of in vitro-produced porcine blastocysts. The increase in quality of later-stage preimplantation embryos may enhance development to full term after embryo transfer.
A ghrelin analogue Hexarelin (HEXr) has been proposed as a regulator of reproductive physiology. We investigated the effects of chronic HEXr administration on reproductive parameters of adult mice. A decreased number of fetuses/corpora lutea in treated females and a downward trend in the pregnancy index and percentage of females impregnated by males treated with HEXr were detected. We propose certain effects of HEXr on the implantation process and/or early development of embryos and over the in vivo reproductive capability of males.
Cryopreservation is relevant to preserve endangered wildlife species or genetic resources in domestic animals. The aim of the present study was to assess the integrity and of frozen–thawed ovarian tissue from bitch after xenografting. Despite a massive follicular loss, a follicle growth was observed at 8 weeks post-transplantation and several well-developed intact secondary follicles were present at the end of the experiment. This confirms canine ovarian tissue is well preserved by our slow freezing process.
Circulating progesterone concentrations during the first week after conception have been associated with increased pregnancy rates in cattle. In the present study, administration of human chorionic gonadotrophin on Day 5 after oestrus resulted in the formation of an accessory corpus luteum (CL) and hypertrophy of the original CL, the result of which was an increase in P4 concentrations from Day 7 onwards. These elevated P4 concentrations were associated with increased conceptus size. Furthermore, conceptus size was highly correlated with interferon-τ secretion in vitro.
Endometrial epidermal growth factor (EGF) regulates cysteine-rich protein 61 (CYR61) and both are implicated in key processes such as implantation and endometriosis. Specific inhibitor studies identified the contribution of Janus kinase 2 (JAK2) and the signal transducer and activator of transcription protein STAT3 to the regulation of CYR61 expression. The data provide new information on signaling EGF-JAK2/STAT3-CYR61 potentially relevant for endometrial physiology.
The use of oocytes grown from preantral follicles could offer a significant alternative for the propagation of livestock as well as for the infertility treatment in human. In this study, the addition of fluid originated from bovine dominant follicles in goat preantral follicles culture medium promoted high rates of in vitro growth. Furthermore, the presence of follicular fluid in the culture of caprine preantral follicles allowed the recover of matured oocytes with ultrastructurally normal organelles.
The mitochondria play crucial roles throughout embryonic development. To investigate whether mitochondrial heteroplasmy affects embryo development, cloned embryos with different levels of mitochondrial heteroplasmy were constructed. Blastocyst formation rates, the expression of pluripotency and mitochondrial regulator genes, and the methylation levels of these genes differed significantly with mitochondrial heteroplasmy. Therefore, mitochondrial heteroplasmy may affect embryonic development.
Males reveal themselves as the weaker sex very early; preterm baby boys are more likely to die of respiratory failure than girls for reasons unknown. Changes in blood flow to the brain and lungs immediately after birth were compared between male and female preterm lambs but were not different. Failure of the circulatory transition at birth, during establishment of independent respiration, is not the cause of preterm males’ vulnerability, and points to a source other than the cardiopulmonary circulation.
Decidualisation of endometrial stromal cells is essential for successful implantation and pregnancy and enhancing decidualization may overcome reduced endometrial receptivity, a major limiting factor in natural and assisted reproduction. The aim of this study was to determine whether dialysed seminal plasma with or without progesterone influenced decidualization of primary human endometrial stromal cells. Seminal plasma potentiated progesterone-induced decidualization, indicating that seminal plasma may enhance endometrial receptivity.