To examine the functional differentiation of chloride cells in the yolk-sac membrane of tilapia (Oreochromis mossambicus) embryos, we developed a 'yolk-ball' incubation system in which the yolk sac was separated from the embryonic body and subjected to incubation in vitro. The yolk-ball preparation consists of the yolk and the covering yolk-sac membrane, which contains a rich population of chlo...

Mutant mice deficient in glucose-6-phosphate dehydrogenase were used to induce teratomas. This enzyme is linked to the X chromosome, which can be inactivated in female embryo. The differences in the enzyme activity between yolk sac mesoderm and embryo versus yolk sac endoderm can be detected in female concepti by using appropriate crosses of wild-type and G6PD-deficient mice. Histochemical stud...

in spite of being histologically benign, sacrococcygeal teratoma (sct) may recur either as a benign or malignant tumor. a total of 26 patients with benign neonatal scts were treated in taleghanee and mofid medical centers from 1986 to 2000. investigations included radiography,abdominal ultrasound and computed tomography (ct) scan and measurement of tumor marker (α-fetoprotein). initial surgical...

Duck hepatitis B virus (DHBV) is the only member of the hepadnavirus family in which nearly 100% vertical transmission from carrier mother to embryo has been reported. Large quantities of maternally transmitted virus particles are present in the yolk prior to incubation of the eggs, and replicative forms of DHBV DNA are detectable in the liver at 6 days of incubation. Since the yolk sac is simi...

Yolk sac hematopoiesis is characterized by restricted hematopoietic cell differentiation. Although multipotent hematopoietic progenitor cells have been identified in the early yolk sac, long-term multilineage repopulating (LTMR) hematopoietic stem cell (HSC) activity has not been demonstrable before day 11 postcoitus (PC) using standard transplantation assays. In the present study, day-10 PC yo...

alpha-fetoprotein producing gastric cancer accounts for less than 10% of the gastric adenocarcinomas. different histologic subtypes may exist, the least common of which is yolk sac morphology. to the best of our knowledge less than 10 cases have been reported with high alpha-fetoprotein and yolk sac components, either pure or mixed with ordinary adenocarcinoma of the stomach. during 10 years, f...

Gastric yolk sac tumors are extremely rare and their prognosis is poor; most patients have widespread metastases at the time of diagnosis. The treatment of gastric yolk sac tumors consists of aggressive chemotherapy combined with radiotherapy and surgery. Here, we first report a case of gastric yolk sac tumor presenting as an early gastric cancer that was cured after a gastrectomy with lymphade...

Previous experiments have proved that thermodynamically unstable calcium carbonate vaterite can exist for long periods in the yolk sac of a pigeon embryo. The aim of this article was to demonstrate the effect of in vitro mineralization of yolk sac fluid on calcium carbonate by direct precipitation. Experiments were conducted using pigeon yolk sac fluid and using lecithin extracted from pigeon y...

Maternal lipoproteins provide nutrients to the fetus via the placenta, yolk sac, and uterine membrane plus decidua. To determine the transport processes that are responsible for the removal of lipoproteins from the maternal circulation, we measured the clearance rates of maternal LDL and HDL in vivo, as well as the tissue distribution of expression of the LDL receptor, glycoprotein 330 (gp330) ...