The rete testis of birds.

The rete testis in the domestic fowl (Gallus gallus domesticus), Japanese quail (Coturnix coturnix japonica), guinea-fowl (Numida meleagris galeata) and drake (Anas platyrhynchos) was studied histologically and with both the scanning and transmission electron microscopes. All the birds have rete epithelial cells varying between squamous and high cuboidal. A cilium-like structure projects from the luminal portion of most cells into the rete lumen, and the outline of the cells varies from polygonal to elongate. Sparse, stubby microvilli were concentrated on the cell borders. Ultrastructural features suggest only moderate secretory and absorptive activities in the cells. The rete testis of birds is amply supplied with blood as well as lymphatic vessels and nerves. Intraepithelial lymphocytes form part of the rete epithelium, and macrophages are present in large numbers in the rete lumen of the domestic fowl and drake and, to a lesser degree, also in the rete epithelium of the drake.