The medaka, Oryzias latipes is a useful animal model for the study of primary vasculature in vertebrate embryos. Using benzidine stain for erythroid cells, we found presumptive erythropoietic foci in the yolk sac vitellolysis zone at stage 39. These foci were present in the yolk syncytial layer, in the extravascular and vitellolysis zone from 9 days post fertilization (dpf) to 11 dpf, and then ...

Transforming growth factor-b1 (TGF-b1) is expressed in the adult and embryonic vasculature; however, the biological consequences of increased vascular TGF-b1 expression remain controversial. To establish an experimental setting for investigating the role of increased TGF-b1 in vascular development and disease, we generated transgenic mice in which a cDNA encoding a constitutively active form of...

Rat embryos (9.5 days gestation) were cultured for 48 h in heat-inactivated homologous serum containing [3-14C] serine. Analysis of the distribution of the radioactive label in the conceptus demonstrated that almost one half of the incorporated serine was cleaved to provide one-carbon units for the synthesis of purine and pyrimidine nucleotides. Analysis of the free amino acids in the serum, th...

To better understand the relationship between the embryonic hematopoietic and vascular systems, we investigated the establishment of circulation in mouse embryos by examining the redistribution of yolk sac-derived primitive erythroblasts and definitive hematopoietic progenitors. Our studies revealed that small numbers of erythroblasts first enter the embryo proper at 4 to 8 somite pairs (sp) (e...

Transforming growth factor-beta(1) (TGF-beta(1)) is expressed in the adult and embryonic vasculature; however, the biological consequences of increased vascular TGF-beta(1) expression remain controversial. To establish an experimental setting for investigating the role of increased TGF-beta(1) in vascular development and disease, we generated transgenic mice in which a cDNA encoding a constitut...

This study investigated effects of microalgae (Rhodomonas baltica) and heterotrophic protists (Oxyrrhis marina) on the daily growth, activity, condition and feeding success of Atlantic herring (Clupea harengus) larvae from hatch, through the end of the endogenous (yolk sac) period. Yolk sac larvae were reared in the presence and absence of microplankton and, each day, groups of larvae were prov...

The rat parietal yolk-sac and its adherent epithelial cells were examined at various stages of gestation using an en face technique. Specimens were observed a both the light and electron microscopic level. Diastase pretreatment and PAS-staining were used to determine the presence of glycogen. As early as the 12th day of gestation the cytoplasm of the parietal yolk-sac cells contained numerous r...

Yolk sac tumor is the most common tumor of testis in children below 3 years. Most of these tumors present as painless, enlarged testicular masses. They are most frequently associated with elevated alpha fetoprotein (AFP) levels. We report a case of yolk sac tumor in an 11 month old child who presented as a painless testicular mass.

The most frequent location for non-metastatic germ cell tumors is the anterior mediastinum. Primary lung germ cell tumors are an exception in medical literature being limited to just a few cases of choriocarcinomas and rare cases of yolk-sac tumors. In this paper, we report a case of a pulmonary yolk-sac tumor with atypical characteristic as regards its diagnosis and treatment.