Reproduction, Fertility and Development
Volume 25 Number 2 2013
RESEARCH FRONT: Ovarian Angiogenesis
Little is known regarding factors that regulate the establishment of vasculature in the ovary. Formation of ovarian structures is initiated in close proximity to vasculature and expression of pro-angiogenic Vegfa isoform mRNA is increased compared to anti-angiogenic Vegfa during primordial follicle assembly in rats. Elucidation of specific genes that affect vascular development may be critical for determining the normal mechanisms of ovarian morphogenesis and understanding ovarian reproductive disorders.
The establishment of a vascular tree in a gland is essential for guaranteeing an adequate supply of oxygen, nutrients and hormones needed for its proper function. This review summarizes evidence for the involvement of low oxygen tension (hypoxia) in the corpus luteum in the transcriptional regulation of genes involved in angiogenesis. The hypoxic microenvironment that occurs in fast-growing tissue such as the corpus luteum is a major contributor to its ability to survive via the induction of vascular network.
The corpus luteum (CL) is a transient endocrine organ that produces progesterone to achieve pregnancy. It grows rapidly from the site of ovulation with extremely active angiogenesis, like a ‘transitory tumour’. The exquisite balance between angiogenesis and the differentiation of steroidogenic cells is regulated by timely recruitment of immune cells. Neutrophils and macrophages are novel pivotal regulators not only of innate immunity, but also the success of pregnancy by accelerating angiogenesis to build up the CL.
The ovary, with its predictable cycles of growth and regression of new blood vessels, has been used to identify and study key molecular pathways involved in angiogenesis. This review describes the potential for the therapeutic manipulation of ovarian angiogenesis and the translation of these findings into the clinic. Some treatments are already in clinical use and there is real potential for the development of additional therapies in the future.
RD12182Fibroblast growth factor 2 induces the precocious development of endothelial cell networks in bovine luteinising follicular cells
An increased mechanistic understanding of the establishment of the corpus luteal vascular tree within the ovary is of critical relevance to the development of novel strategies to improve fertility. In the present study, we showed that the angiogenic factor, fibroblast growth factor 2 (FGF2) was essential and stimulated the earlier development of endothelial tubule-like networks in vitro. This provides further evidence that FGF2 is major contributor in the initiation of luteal angiogenesis.
RD12021Intra-uterine growth retardation affects birthweight and postnatal development in pigs, impairing muscle accretion, duodenal mucosa morphology and carcass traits
Adequate uterine capacity and placental function are crucial for normal fetal growth and development in all species. This study investigated the occurrence of intra-uterine growth retardation in pigs of different birthweight ranges and its impact on their subsequent development. A lower percentage of muscle fibres and a higher percentage of connective tissue in the semitendinosus muscle, greater fibre density and a lower height of the duodenal mucosa was found in low-birthweight pigs. Hence, low-birthweight animals will lead to greater economic losses to swine producers, which raise questions about the economic reality of rearing low-birthweight pigs.
There is much interest in recent years in the use of stem cells to study male and female germ cell development and eventually provide novel diagnostic and/or therapeutic applications. Here, the current state of the field of differentiation of germ cells is reviewed with a focus on the use of both human embryonic stem cells and induced pluripotent stem cells. Results to date suggest major hurdles that will need to be overcome if clinical applications are to be realised.
RD11313Altered pregnancy outcomes in mice following treatment with the hyperglycaemia mimetic, glucosamine, during the periconception period
Exposure of oocytes to the hyperglycaemia mimetic, glucosamine, during in vitro maturation impairs embryo development. This study demonstrates that in vivo glucosamine administration during the periconception period also has adverse effects on embryonic and fetal development in mice, with the nature of the effects dependent on maternal age. These results suggest that further studies should consider a potential role for altered activity of the hexosamine biosynthesis pathway in contributing to the effects of periconceptional maternal hyperglycaemia.
RD12033Sex determination of porcine embryos using a new developed duplex polymerase chain reaction procedure based on the amplification of repetitive sequences
Sex determination and selection in the pig has a real impact in livestock breeding programmes. In the present study, we developed a new procedure based on the amplification of porcine-specific repetitive sequences for the rapid, reliable and efficient sex determination of porcine embryos and single cells. This is one of the few successful sexing methods in the pig and it might be used to deal with sex-dependent differences in porcine embryo physiology and manipulating sex ratios of offspring.
RD11305Microarray analysis of mRNA from cumulus cells following in vivo or in vitro maturation of mouse cumulus–oocyte complexes
In vitro maturation continues to produce oocytes of poorer competence than those mature in vivo, despite potential benefits for clinical infertility treatment and animal breeding. Cumulus cells are important to oocyte health, so we examined differences in the global gene expression of cumulus cells from in vivo- and in vitro-matured cumulus–oocyte complexes. Important gene expression differences were revealed that reflected differences in cumulus cell function. This included haemoglobin, which is found only within cumulus cells of in vivo-matured oocytes.
RD12024Genotype and fetal size affect maternal–fetal amino acid status and fetal endocrinology in Large White×Landrace and Meishan pigs
Differences in the size of fetuses sharing the same uterus may be related to their amino acid or hormone concentrations, as both regulate fetal growth. This study highlighted novel differences in placental protein secretion, maternal and fetal amino acid status and fetal hormone concentrations between diverse pig breeds and between feto–placental units of different size within the same uterus. Strategies to optimise fetal growth should integrate both maternal and local feto–placental factors.
RD11315ROCK inhibitor Y-27632 enhances the survivability of dissociated buffalo (Bubalus bubalis) embryonic stem cell-like cells
It is very difficult to maintain dissociated buffalo embryonic stem (ES) cells in culture. Supplementation of ES cell culture medium with Y-27632, a specific inhibitor of Rho kinase activity, was found to improve survival of buffalo ES cells under unfavourable conditions such as enzymatic dissociation to single cells or antibiotic-assisted selection after transfection, without compromising their pluripotency. It may help in developing better protocols for production of transgenic buffalo embryos.
RD11228Daily prolactin pulse inhibits the corpus luteum during lactational quiescence in the marsupial, Macropus eugenii
In kangaroos and wallabies the hormone prolactin controls lactation and simultaneously inhibits the next pregnancy by suppressing progesterone secretion from the ovary. We showed that a single short-duration pulse of prolactin once per day maintains progesterone inhibition but not if the interval between pulses is more than 48 h. This is the opposite of prolactin’s role of stimulating progesterone secretion in all other mammals so far studied.