Search results for "Yolk"
showing 4 items of 64 documents
Antiphosphatidylserine Antibodies Affect Rat Yolk Sacs in Culture: a Mechanism for Fetal Loss in Antiphospholipid Syndrome
2004
PROBLEM: A variety of reproductive impairments have been reported in the context of the antiphospholipid syndrome (APS). APS is associated with the presence of antibodies to negatively charged phospholipids that may affect the outcome of pregnancy. METHOD OF STUDY: Rat embryos were cultured within their yolk sacs. The effects of two antiphosphatidylserine monoclonal aPS antibodies (HL5B, RR7F) regarding their influence on growth and apoptotic events of the yolk sacs, as well as on growth and the morphology of the embryos, were studied. RESULTS: Exposure of rat embryos and their yolk sacs to aPS inhibited yolk sac growth. Moreover, increased number of apoptotic events of giant cells in the a…
Identification of the yolk receptor protein in oocytes of Nereis virens (Annelida, Polychaeta) and comparison with the locust vitellogenin receptor
1992
In oviparous animals large amounts of yolk proteins of extraovarian origin are accumulated by developing oocytes during vitellogenesis. The yolk protein precursors, the vitellogenins (VTG), are transported into the oocytes by receptor-mediated endocytosis. In oocytes of the polychaetous annelid, Nereis virens, the receptor protein for VTG was visualized by ligand blotting studies as a protein with an apparent molecular mass of 190 kDa under non-reducing conditions. Anti-Locusta VTG receptor antibodies recognize the Nereis VTG receptor protein. The Nereis VTG receptor protein binds Locusta and Schistocerca VTG; the VTG receptor proteins of both locust species bind the Nereis vitellin. These …
The effects of experimentally manipulated yolk androgens on growth and immune function of male and female nestling collared flycatchers Ficedula albi…
2009
Hormone-mediated maternal effects may be an important mechanism for adjusting offspring phenotype to particular requirements of the environment. We manipulated the levels of testosterone and androstenedione in the yolk of collared flycatcher Ficedula albicollis eggs to investigate the effects of pre-natal exposure to androgens on growth and immune function. Androgen treatment tended to reduce the growth of males, and enhance the growth of females, as indicated by significant interaction between sex and androgen treatment. Cellular immune function was not affected by androgen treatment or sex. Survival of nestlings until fledging was not related to androgen treatment. Our results indicate th…
Maternally‐transferred thyroid hormones and life‐history variation in birds
2022
1. In vertebrates, thyroid hormones (THs) play an important role in the regulation of growth, development, metabolism, photoperiodic responses and migration. Maternally transferred THs are important for normal early-phase embryonic development when embryos are not able to produce endogenous THs. Previous studies have shown that variation in maternal THs within the physiological range can influence offspring phenotype. 2. Given the essential functions of maternal THs in development and metabolism, THs may be a mediator of life-history variation across species. 3. We tested the hypothesis that differences in life histories are associated with differences in maternal TH transfer across species…