The morphological features of the rete testis of the ostrich (Struthio camelus).

The epithelium of the rete testis of the ostrich is simple cuboidal to columnar in nature, unlike the more flattened epithelium encountered in other non-passerine birds. A solitary cilium projects into the ductal lumen. A unique lateral cell membrane modification, similar, in some respects, to a hemi-desmosome, occurs frequently along the length of this membrane. The lateral cell membrane is complexly folded, and the cell contains an abundance of intermediate filaments, particularly in the vicinity of the nucleus and the internal surface of the basal cell membrane. The Golgi complex and endoplasmic reticulum are moderately developed. Another unique feature of the cell is the presence of a solitary, large, heterogeneous lipid body/droplet situated in the immediate supranuclear region of the cell. Overall, the cell structure conveys the impression of a metabolically active cell, which has the capability of transporting material from the duct lumen to the basal part of the cell, and of protein synthesis, apparently much in excess of what is necessary for cellular maintenance and sustenance.