Redifferentiation and subsequent dedifferentiation of the livers of roosters resulting from acute estrogen challenges.

1. Histologic and metabolic changes take place in livers of rooster receiving challenges consisting of acute doses of estrone. 2.

Production of VLDL and vitellogenin(s) in oestrogen-challenged hypothyroid chickens.

Compared with normal control birds of the same breed, obese strain (OS) White Leghorn chickens, exhibiting classical symptoms of hypothyroidism, were generally half as responsive to an oestrogen challenge in terms of synthesis of VLDL and vitellogenins, despite having livers which were, on the average, twice as large. Even the few OS birds which were laying eggs and therefore enjoying a degree of thyroid function, failed to exhibit normal responses to hyperdynamic doses of oestrogens. However, simultaneous injections of triiodothyronine (T3), in the physiological range, and hyperdynamic doses of oestrogenic substances (Ayerst Co.

Serum lipids and lipoproteins in hypothyroidism.

Obese strain (OS) chickens hatched in the NIU vivarium were observed, primarily with respect to serum lipid and lipoprotein parameters, over a period of 36 weeks. The hypothyroid birds began to show differences in total serum lipids as compared to non-OS controls as early as 4 weeks post-hatching. All lipaemic chickens displayed lack (or deficiency) of thyroid tissue.

Changes in expressions of red blood cell antigens following gamma irradiation of chicken embryos.

Red blood cells (RBC) from chicken embryos receiving 450 R of gamma-irradiation on the 6th day of incubation displayed various differences from controls with respect to agglutination properties in the presence of antibodies for three blood group antigens as assayed over a period extending from 12 days of incubation to after hatching. An alloantigen (B21), which normally can be detected prior to 10 days of incubation, showed increased agglutinability following radiation exposure at 6 days. Likewise, an 'embryonic' blood cell antigen, which normally would decrease rapidly after 12 days of incubation, persisted in the blood of irradiated embryos.