Gonadotrophic Activities of Anterior Pituitary and of Blood Plasma and Ovarian Response to Exogenous Gonadotrophin in Moulting Hens

Abstract

The total gonadotrophic activities of the anterior pituitary glands and blood plasma of hens, Gallus domesticus, during the moulting period were estimated using the assay method based on the weight increase of chick testis. The activities in both the pituitary and the blood of hens in the four groups classified according to the progress of moult were significantly higher than those of laying hens. Nevertheless, no detectable level of serum vitellin and a completely regressed ovary were found in moulting hens.Anterior pituitary glands of moulting and laying hens were assayed for their fsh and lh activities by the use of the hcg augmentation method or the ovarian ascorbic acid depletion test. The fsh activity of the moulting hen was about twofold higher than that of the laying hen, whereas lh activity was about equal during the moulting and the laying periods.The serum vitellin of moulting hens increased steeply with the injection of oestrogen over 3 days. When chicken anterior pituitary homogenate was injected once daily for 6 days to hens in the moulting period, a satisfactory follicular growth as in the laying hen was induced in all of the treated hens. Injection of pmsg into moulting hens for 6 days resulted in an increase of serum vitellin in all the hens and the formation of yellow follicles in 40% of the treated hens.These results suggested that the failure of follicular growth in the moulting hen, despite high levels of total gonadotrophic activity in both pituitary and blood, might be due to an unbalanced secretion of endogenous gonadotrophins.

The influence of 5-methoxytryptophol, a pineal compound, on comb growth, ovarian weight, follicular growth and egg production of juvenile, maturing and adult white leghorn hens (Gallus domesticus L.)

“…The total gonadotropin content of the latter in serum (Bailey et al, 1952) as well as in the anterior pituitary (Nakajo et al, 1961) proves to be higher than in the laying hen. Imai et al (1972) found that this high gonadotropin content in the non-laying hen can be attributed to an increase of FSH rather than of LH. Consequently, the suggestion seems to be justified that in maturing and adult hens injected with 5-methoxytryptophol, the weight of the gonadal system (ovaries and follicles) is decreased while the FSH content increases.…”

Administration of pregnant mare serum gonadotropin to Japanese quail (Coturnix coturnix japonica): dose response over seven days and comparison of delivery by daily injection or osmotic pump

“…An increase in ovarian and oviductal mass in response to PMSG was reported in most previous studies (Zadworny and Etches 1988;Petitte and Etches 1989;Wakabayashi et al 1996). In several studies, growth of yellow follicles was observed (Imai et al 1972;Zadworny and Etches 1988;Wakabayashi et al 1996), but these follicles were not arranged in an ovarian hierarchy. Only one study has reported a normal ovarian hierarchy in some individuals following PMSG treatment (Petitte and Etches 1989).…”

“…Previous experiments have used either daily injections (e.g. Imai et al 1972;Johnson et al 1985;Petitte and Etches 1989) or the implantation of an osmotic pump (Wakabayashi et al 1992(Wakabayashi et al , 1996 to deliver hormone. Both methods have their advantages and disadvantages.…”

Effects of Avian and Mammalian Pituitary Preparations on Follicular Growth in Hens Treated With Methallibure or Fasting

“…The laying pullets of one group were fed Methallibure (ICI compound 33828) at a concentration of 0-02% in the normal dry-mash ration based on the results of preliminary experiments using 0-01% and 0-02% concentrations (Sykes, 1964 Serum vitellin levels were measured by the immunological procedure described previously (Imai, Tanaka & Nakajo, 1972 Kiyoshi Imai carboxymethyl (CM)-or diethylaminoethyl(DEAE)-cellulose was used for a further purification. The GP-extract obtained from each batch of CAP was dissolved in 5 ml 4 mM-ammonium acetate at pH 5-5.…”