The uptake of [3H]leucine by the rat yolk sac and embryo and the subsequent synthesis of albumin and transferrin have been studied in whole embryo culture. Rat embryos of 12 days gestation were used in all experiments. Isotopically labelled transferrin was detectable in yolk-sac and embryo tissue extracts. In contrast, [3H]albumin could not be found in either tissue extract. Levels of radioacti...

The yolk sac is phylogenetically the oldest of the extraembryonic membranes. The human embryo retains a yolk sac, which goes through primary and secondary phases of development, but its importance is controversial. Although it is known to synthesize proteins, its transport functions are widely considered vestigial. Here, we report RNA-sequencing (RNA-seq) data for the human and murine yolk sacs...

The role of thrombopoietin (Tpo) in promoting hematopoiesis has been extensively studied in late fetal, neonatal, and adult mice. However, the effects of Tpo on early yolk sac hematopoiesis have been largely unexplored. We examined whole embryos or the cells isolated from embryo proper and yolk sacs and identified both Tpo and c-mpl (Tpo receptor) mRNA transcripts in tissues as early as embryon...

The mass of residual yolk sac expressed as a percentage of initial mass of the egg from which the chick hatched decreased sharply in the first 2 days post-hatching. A gradual reduction occurred between 3 and 10 days after which a sharp decline was noted between 11 and 13 days post-hatching. The highest number of chicks with unabsorbed yolk sac was noted on day 5 post-hatching followed by days 6...

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...

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...