I N almost all embryos yolk becomes converted into cytoplasm. It has not previously been possible to describe in any detail the morphological changes involved in this process; indeed, when the yolk drops contained within embryonic cells are examined by light microscopy they seem to remain in much the same condition until they are suddenly used up. For this reason they have frequently been consi...

Progenitor cells capable of giving rise to functional macrophages in in vitro culture were first detectable in the fetal yolk sac of the mouse between day 7 and 8 of gestation. Macrophage progenitors were not detectable outside the yolk sac until day 11. Although the early yolk sac contained macrophage precursors, no cells with the morphologic or functional characteristics of mouse promonocytes...

Thyroid hormones (THs) are essential for the correct development of nearly every structure in the body from the very early stages of development, yet the embryonic thyroid gland is not functional at these stages. To clarify the roles of the egg yolk as a source of THs, the TH content in the yolk and the expression of TH regulator genes in the yolk sac membrane were evaluated throughout the 21-d...

Background: Egg yolk (EY) is well known to be toxic for buck spermatozoa, which creates restrictions of its use in cryopreservation. Therefore, this study compare the effect different levels gum Arabic (GA) an extender on quality and fertility cryopreserved sperm. Methods: Each ejaculate six bucks was frozen Tris with one concentrations GA contained 3, 6, 9 12 gm/ 100 ml place EY. Control conta...

To study the pathogenesis of cholesterol gallstones, we fed 24 adult male prairie dogs a high cholesterol, egg yolk diet. 13 control animals received a cholesterol-free diet. All animals fed the egg yolk diet formed multiple gallstones in 2-6 months' time. These stones contained cholesterol, 77+/-14% by dry weight. No stones ocurred in the control group. The egg yolk-fed animals developed bile ...

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...

background in recent decades, bacterial antibiotic resistance (especially in enterococci) has become a significant problem for human and veterinary medicine. one of the most important antibiotic resistances in enterococci, vancomycin resistance, is encoded by van gene family. objectives the aim of this study was to investigate antibiotic resistance to vancomycin in enterococci and the genes res...