Abstract
It has been well established that the ovarian estrogenic hormone is responsible for prompt increases in calcium, phosphorus, fat, lipid and phosphoprotein (serum vitellin) in the serum of the fowl at the time of egg production, and that the administration of estrogen to the immature chick induces the increase in these substances in the serum.
The purpose of the present study is to determine by the serological technique if there exist sex and age differences in the serum vitellin production induced by the administration of estrogen to the chick.
The chicks used in this experiments were furnished from the flock of S. C. White Leghorn, in National Institute of Agricultural Sciences, ChibaShi, Japan.
Anti-vitellin serum used in this experiments, was that immunity serum prepared by injecting the serum of the laying hen to rabbit, from which species specific antibody was excluded with the serum of the cock, and the potency of which is illustrated in Table 1.
Diethylstilbestrol (solution of 50mg. of stilbestrol in 20cc. of sesame oil) was injected intramuscularly to the chick in various daily doses.
Blood was collected from the wing vein of the estrogenized chick daily, from which the serum was separated by a centrifuge. (Antigen.)
Interfacial precipitation test was used for detecting the presence of serum vitellin.
The results obtained from the experiment with the groups in which estrogen injection was started on the 21st and 41st day after hatching are illustra ted in Table 2 and Table 3 respectively. Distinct sex difference was not observed in both experimental groups.
In both sexes the appropriate daily doses of estrogen fit enough for 20 day-old chicks and 40 day-old chicks to induce the serum vitellin production on the 5th day or so after the beginning of the injection were 0.25mg. and 0. 375mg. respe ctively.
Daily injection of 0.125mg. of stilbestrol proved to be effective to induce serum vitellin production about on the 7th day after the beginning of the injection in 20 day-old chicks of each sex, but not effective in 40 day-old chicks in spite of injections for 20 consecutive days. These results may imply the existence of that threshold value of daily dose of estrogen fit enugh to induce the serum vitellin production, which increases in proportion to the increasing age and live-weight of the chick.
Table 4 demonstrates the results obtained from the experiments with the group injected daily with estrogen from the 61st day after hatching, showing a significant delay in the appearance of the response in male chicks as compared with female chicks in every experimental lot of different dose.
A similar tendency was observed in the experiments with the group, in which the estrogen injection started on the 91st day after hatching (Table 5).
In both experimental groups of 60 day-and 90 day-old chicks, the daily doses of estrogen appropriate enough to induce the serum vitellin production on the 5th day or so after the beginning of the injection for males and females were estimated to be 0.50-0.625mg. and 0.25-0.375mg. respectively.
It appeared that the female chicks became more sensitive to estrogen for the serum vitellin production in the liver than the male chicks, being stimulated by the successive secretion of endogenous estrogen, even if in a small amount, from their own ovaries, which presumably augmented the activity in about 40-60 days of age. Further experiments with castrated males and ovariectomized females will be needed on this point.
