Ultrastructure of the male reproductive system of the trematode Brachylaimus aequans.

The transmission electron microscopic studies of the trematode Brachylaimus aequans revealed that the seminal vesicle and ejaculatory duct are lined with syncytial epithelium with numerous lamellate processes. The cirrus and genital pore are covered with a spineless tegument, which is almost identical with the body tegument. The testes contain tailed spermatozoa developing during spermiogenesis from biflagellate spermatids whose flagella (9 + 1) fuse with the median cytoplasmic process. The lumina of seminal vesicle, ejaculatory duct and cirrus are filled with spermatozoa.