THE MORPHOLOGY OF THE MALE REPRODUCTIVE STRUCTURES OF PERIONYX EXCAVATUS (OLIGOCHAETA)

Perionyx excavatus (Oligochaeta) is a vermicomposting earthworm of whi ch the reproductive strategies are little known. In order to obtain mo re information on this, its reproductive systems were studied. Existin g literature on the topic is either contradictory or scant. The invest igation was done by examining the gross anatomy and histology, using s canning and transmission electron microscopy. The male reproductive sy stem consists of two pairs of testes in segments 10 and 11 and two pai rs of seminal vesicles in segments 11 and 12. In mature worms the deve loping spermatozoa are released by the testis into the body cavities o f segments 10 and 11. The seminal vesicles in a particular segment rec eive developing spermatozoa from the lumen of the preceding segment. T wo pairs of ciliated sperm funnels also occur in segments 10 and 11 an d become the ciliated vasa deferentia carrying the sperm. The vasa def erentia on each side fuse to form only one vas deferens. These vasa de ferentia reach the pair of prostatic glands in segment 18, each joinin g the prostatic duct and opening via the ventral male openings adjacen t to each other on segment 18. Associated with the male openings are r etractable penial chaetae. The cellular composition and organelle dist ribution of some organs and structures are also described. The positio ns of the female reproductive structures are illustrated diagrammatica lly in this paper.