Nutrient needs central to satisfactory egg incubation well-being undergo several major changes from fertilization until the reliance of the chick on feed. Glucose is central, with the initiation of incubation until the chorioallantois accesses O(2) to use for fatty acid oxidation. Nutrient recovery from albumen and yolk is largely commensurate with body assembly through to completion of the emb...

The use of avian animal models has contributed to the understanding of many aspects of the ontogeny of the hematopoietic system in vertebrates. However, specific events that occur in the model itself are still unclear. There is a lack of consensus, among previous studies, about which is the intermediate site responsible for expansion and differentiation of hematopoietic cells, and the liver's c...

OBJECTIVE Molecular pathways governing blood vessel patterning are vital to vertebrate development. Because of their ability to counteract proangiogenic factors, antiangiogenic secreted Sema3 (class 3 semaphorins) control embryonic vascular morphogenesis. However, if and how Sema3 may play a role in the control of extraembryonic vascular development is presently unknown. APPROACH AND RESULTS ...

We have analysed the function of transforming growth factor beta (TGF-beta) in yolk sac development in mice by generating somatic chimaeras in which the extraembryonic mesoderm, which gives rise to the endothelial and haematopoietic cells of the yolk sac vasculature, is derived from embryonic stem (ES) cells. The ES cells were stably transfected and express either the full-length type II bindin...

STUDY QUESTION Is there an association between chorionic villous vascularization, ultrasound findings and corresponding chromosome results in early miscarriage specimens from a cohort of recurrent pregnancy loss patients? SUMMARY ANSWER We did not find a significant difference in vascularization scores of chorionic villi between embryonic, yolk sac or empty sac miscarriages, or between euploi...

INTRODUCTION Requests for termination of pregnancy (TOP) at very early gestation (≤6 weeks) can prove challenging for abortion services as the ultrasound feature usually accepted as definitive evidence of an intrauterine pregnancy (IUP), the presence of a yolk sac within a gestational sac, may not yet be evident. In 2011 the Edinburgh TOP service introduced a protocol permitting women to procee...

The effects of broiler breeder age (26, 28, and 30 wk) and incubator relative humidity (43, 53, and 63% RH) on yolk sac weight and composition in broiler hatching eggs between 16 and 19 d of incubation were evaluated. Percentage yolk sac weight was reduced in eggs from the youngest (26 wk) breeder hens and in eggs incubated at 53% RH. Percentage yolk moisture, in eggs from the youngest hens, wa...

Yolk sac tumors (endodermal sinus tumors) are an important subgroup of germ cell tumors of the ovary. They are seen in young females and are highly aggressive, but respond well to treatment. Although different morphological patterns can be seen on light microscopy, granulomatous reaction and giant cells are a very rare occurrence. We report the case of a young female with ovarian yolk-sac tumor...

Yolk sac tumors, the most common germ cell tumor in young infants and children, however, are distinctly uncommon site in the vagina. A baby with bleeding per vaginum since one month presented at 9 months of age with raised Serum αfetoprotein (AFP) but normal levels of ß-HCG and CA-125 is reported. Fine needle aspiration from the mass yielded material suggestive of a germ cell tumor. The histopa...