Precocious Development of Sexual Characters in the Fowl by Daily Injections of Hebin. I. The Male. ∗

Abstract

In a previous report the precocious development of sexual characters following homeoplastic hypophyseal implants in cockerels was discussed. 1 The present report concerns the effects of daily administrations of hebin, a purified gonad-stimulating hormone prepared from sheep pituitary glands, on the juvenile sex characters of cockerels. 2

Light brown Leghorn cockerels ranging from 21 to 47 days at the beginning of the experiment received daily injections of hebin over a period ranging from 14 to 36 days. The daily dosages administered per bird varied from 4 to 32 rat units. Treated and control birds were weighed and head furnishings measured at regular intervals. Treated individuals, with but one exception, remained active and in good condition throughout the duration of the experiments.

The first effect to be noticed was a pronounced stimulation of head furnishings, in some instances, as early as 48 hours after injections began. These became turgid and reddish in color and revealed steady growth throughout so that at the conclusion of experiments they were usually perceptibly larger than controls—in some instances very considerably, so. Bird No. 250, 28 days old when the experiment began, received 20 rat units daily for 21 days. The day the experiment began its comb measured 2.0⁺ cm. in length and 0.8⁺ cm. in height, while 21 days later its comb measured 7.3 cm. in length and 3.7 cm. in height. The largest control comb measured but 4.3 cm. in length and 1.8 cm. in height at the conclusion of the experiment, though its size at the beginning was similar to that of the treated individual. Some of the older individuals were known to crow and attempt treading, a reaction not exhibited by normals until considerably older.† Plumage and spurs revealed no noticeable modifications.