Studies on the Cloacal Gland of the Quail

Abstract

During the breeding season, the male quail (Coturnix coturnix japonica) exhibits, as is well known, such puzzling sexual characteristics as extrusion of a frothy white fluid from the anus and swelling of the dorsal wall of the cloaca. In the present paper, these characteristics of the male quail were studied macroscopically and microscopically.In the breeding male, the mucosa of the cloaca was slightly protruded on the cloacal surface from the opening of the bursa fabricius to the dorsal lip of the cloaca. In this mucosal protrusion, there was located a well-developed gland, which was named the cloacal gland by COIL AND WETHERBEE (1959). The gland consisted of agregates of small glands which were separated from one another by a thin septum of connective tissue rich in elastic fibers. The individual gland was like a long sack and opened directly into the cloaca with a small papilla. The gland was lined by a single layer of tall columnal cells with a round nucleus near the basis. The lumen of the gland was enlarged, showing complicated epithelial folds. The cytoplasm of the glandular cell contained a large number of secretion droplets and appeared somewhat light. The gland was a mucous one in function, because the droplets in the cytoplasm, as well as secretions in the lumen, were readily stained with such mucin stains as alcian blue, aldehyde fuchsin, and periodic acid-Schiff. The frothy fluid from the cloaca was actually originated from this cloacal gland.The development and secretion of the gland, however, depended on the sex and sexual maturity of the individual bird. In the bird after hatching, the gland was of slightly convoluted tubular form and located sparsely in the mucosa. Thereafter, it developed slowly, regardless of sex difference, until sexual maturity was reached. In the breeding season, the gland of male abruptly became hypertrophic and functional, while that of the female remained unchanged. When the sexual activity was declined, the gland of the male became atrophic proportionally. These observations suggest that the cloacal gland may be under the control of testicular hormones in the male.In the breeding male, an arc-shaped, reddish swelling on the dorsal cloacal wall was formed by a local thickening of the circular muscle around the cloaca, just dorsal to the gland. The swelling, or the thickening of the muscle, disappeared in accordance with a decline in sexual activity. Such thickening of the muscle was not presented in the breeding female. This suggests that the development of the sphincter muscle of the cloaca may also be under the control of testicular hormones, as the cloacal gland is. The development of the circular muscle appears to be related to the discharge and frothing of secretions from the cloacal gland. Namely, the thickened muscle may act on the underlying cloacal gland in such a manner as to squeeze out the secretions of the gland into the cloaca by its strong constriction, which may also cause the secretions frothy.