Vascular remodeling of the mouse embryonic yolk sac is a highly dynamic process dependent on multiple genetic signaling pathways as well as biomechanical factors regulating proliferation, differentiation, migration, cell-cell, and cell-matrix interactions. During this early developmental window, the initial primitive vascular network of the yolk sac undergoes a dynamic remodeling process concur...

Primary yolk sac tumour of the liver is exceedingly rare. A 28 year old woman presented with a cystic liver mass and a markedly raised serum alpha-fetoprotein concentration. She underwent a partial hepatectomy for a suspected hepatocellular carcinoma but histological examination of the tumour revealed the classical morphological and immunohistochemical features of a yolk sac tumour. There was n...

Apolipoprotein expression was examined in the postimplantation mouse embryo. Antibodies directed against murine Apolipoprotein AI and human low-density lipoprotein (LDL) particles specifically immunoprecipitated metabolically labelled radioactive apolipoproteins from the culture supernatant of 10.5 days post coitum (days p.c.) yolk sac visceral endoderm cultured in vitro. No evidence for apolip...

Yolk sac tumor (YST) is a common malignant primitive germ cell tumor that often exhibits differentiation into endodermal structures. They most commonly occur in childhood and adolescence and are rare after the age of 40 years. Derived from the yolk sac during the embryonic period, YSTs can occur in the gonads and germ cells because the tumor cells migrate from the yolk sac toward the gonads. He...

Whether embryonic and adult blood derive from a single (yolk sac) or dual (yolk sac plus intraembryonic) origin is controversial. Here, we show, in Xenopus, that the yolk sac (VBI) and intraembryonic (DLP) blood compartments derive from distinct blastomeres in the 32-cell embryo. The first adult hematopoietic stem cells (HSCs) are thought to form in association with the floor of the dorsal aort...

This study was aimed to observe the correlations among egg, larvae and maternal characteristics of Persian sturgeon. A total of 41 females were used and the variables including fertilization rate, incubation survival rate, larvae survival rate during yolk sac absorption (before feeding), and larvae survival rate after first feeding were determined. As a result, fertilization rate was positively...

Blood islands, the precursors of yolk sac blood vessels, contain primitive erythrocytes surrounded by a layer of endothelial cells. These structures differentiate from extra-embryonic mesodermal cells that underlie the visceral endoderm. Our previous studies have shown that Indian hedgehog (Ihh) is expressed in the visceral endoderm both in the visceral yolk sac in vivo and in embryonic stem (E...

The yolk sac membrane plays a major role in the transport of nutrients from the yolk contents to the chick embryo. We examined whether the yolk sac membrane expresses genes for nutrient digestion, enzymes, and nutrient transporters. We evaluated relative mRNA abundance of the digestive enzymes aminopeptidase N (APN) and sucrase-isomaltase (SI); the nutrient transporters oligopeptide transporter...

Calcium, magnesium, copper, iron and zinc are stored in hens’ egg yolk and, except for copper, the majority of these minerals are located in egg yolk granules (Table 1). Presumably, up to 90% calcium, magnesium, iron and zinc are firmly bound in the phosvitin-lipovitellin complex of granules (GREENGARD et al., 1964; TABORSKY, 1980; TUPPER et al., 1954). As was discussed by Richards, copper ions...

background: colibacillosis is one of the most economically important diseases of poultry worldwide. objectives: this study was conducted to examine the clonal relatedness and typing of 95 avian escherichia coli isolates by eric-pcr. methods: sixty-three e. coli isolates from two common manifestations of colibacillosis (yolk sac infection and colisepticemia) and 32 isolates from feces of apparen...