Does Castration in Guinea Fowls Produce Sexual Differentiation in Plumage and Changes in Head Furnishings?

Abstract

In guinea fowl there are no sex differences in shape, pigmentation and pattern of plumage, and but slight difference in development of head furnishings (comb and wattles are a little larger in cocks). In comparison with common fowls the guinea fowl feathers are of henlike type, having short and rounded ends. This fact raises the question whether the sexual uniformity in feathering in guinea fowl is of the same nature as that of the Sebright bantams according to Morgan's findings. Finlay reported 2 castrations of guinea fowl cocks, with negative results. In the present study both cocks and hens were castrated, and resulting changes in head furnishings and plumage carefully measured. Five cocks and 5 hens (same stock) were castrated at the age of 5 months on September 19, 1930. One week after castration certain feathers of left neck, back and tail were pulled out; corresponding feathers on the right side served as control, and after 5 months the animals were killed. Complete castration had been obtained in 3 cocks and one hen. In one cock small spherical regenerates on both sides, and in another cock a similar regenerate of testicular tissue on the left side, were found (0.05-0.1 g.). One hen regenerated on the left side an ovarian tissue with 7 macroscopically identifiable follicles (weight 0.0456 gm.); a second hen had a spherical regenerate with typical testicular tissue containing spermatozoa (sex reversion); a third hen showed a tissue histologically resembling an embryonic sexually indifferent gonad; the fourth hen had an hypertrophied right ovary (weight 0.0255 gm.), likewise showing the structure of a sexually indifferent gonad.