Cloacal morphology of Nothura maculosa (Temminck, 1815), Aves tinamiformes

Cloacae of male Nothura maculosa (spotted tinamous) were dissected and studied with routine histological and histochemical techniques. In the cloaca of this species the following cranio-caudally oriented regions can be recognized: the coprodeum, the urodeum and the proctodeum, separated by the coprourodeal and the uroproctodeal folds respectively. The coprodeum is an abrupt dilatation of the rectum which receives the ureters, contrary to other birds in which they open into the urodeum. The urodeum is the smallest compartment of the cloaca. Its wall presents the paracloacal vascular bodies and the ductus deferens receptacles which open into the ejaculatory fossa through a pair of papillae. The ejaculatory fossa forms the ventral floor of the urodeum and is characterized by the presence of a secretory epithelium and a lamina propria showing rich vascularization. The proctodeum is connected to the exterior through the cloacal opening and ventrally it presents the phallic structures and the proctodeal lamella. Its dorsolateral wall forms the cloacal bursa, its mucosa shows morphological variations depending on the degree of regression. Enclosing the uroproctodeal wall are the cloacal sphincter muscle and the skin.