OBJECTIVE To review the process of blood-cell formation in the murine and human yolk sac. DATA SOURCES Most articles were selected from the PubMed database. DATA SYNTHESIS The yolk sac is the first site of blood-cell production during murine and human ontogeny. Primitive erythroid cells originate in the yolk sac and complete their maturation, including enucleation, in the bloodstream. Thoug...

Background: During the past 20 years a lot of information is achieved about the first trimester of pregnancy through ultrasound and intrauterine fertilization. Many researchers tried to use the symptoms of ultrasound in early pregnancy like measuring the gestational sac and yolk sac of the pregnancy to predict the continuation of pregnancy. Aim of the recent study is to predict the risk of spon...

objective: on a global scale, stratospheric ozone depletion has caused an increase in uv-b radiation reaching the earth's surface. ultraviolet radiation has long been suspected to be harmful to aquatic organisms. materials and methods: in order to study ionocyte localization (by na+/k+-atpase immunolocalization) and the effects of uv radiation on the ionocytes of skin and gills, the alevins of ...

Address for Correspondence: Dr. Geetanjali Srivastava, Junior resident IIIrd year,Department of Anatomy, Era’s Lucknow medical college, Lucknow-226003, Uttar Pradesh, India. 9792171135, E-Mail: [email protected] Introduction: The yolk sac is the first extra embryonic structure that becomes sonographically visible within the gestational sac and acts as the primary route of excha...

The mechanisms involved in the induction of yolk sac mesoderm into blood islands and the role of visceral endoderm and mesoderm cells in regulating the restricted differentiation and proliferation of hematopoietic cells in the yolk sac remain largely unexplored. To better define the role of murine yolk sac microenvironment cells in supporting hematopoiesis, we established cell lines from day-9....

In order to evaluate the hypothetical activity of foetal hepatic factors on putative yolk-sac haemopoietic stem cells we used the Double Diffusion Chamber (DDC) techniqUe. The DDC were made of a regulator compartment, where foetal hepatic tissue was introduced and a test compartment where visceral yolk-sac cells were cultured. In this system a hepatic signal induced the yolk-sac stem cells to d...

Mouse embryos lacking the polycomb group gene member Yin-Yang1 (YY1) die during the peri-implantation stage. To assess the post-gastrulation role of YY1, a conditional knock-out (cKO) strategy was used to delete YY1 from the visceral endoderm of the yolk sac and the definitive endoderm of the embryo. cKO embryos display profound yolk sac defects at 9.5 days post coitum (dpc), including disrupte...

Rat embryos, explanted with their embryonic membranes during the early stages of organogenesis (H-l (H days gestation), were grown in culture in roller tubes. Yolk-sac antibody (sheep anti rat yolk-sac gamma globulin), known to be teratogenic when injected into pregnant rats, was added to the culture medium. At concentrations of 01 mg/ml or more the antibody caused gross retardation of growth a...