The structure and development of the spermatozoon of Aspiculuris tetraptera (nematoda)

Abstract

The mature spermatozoon of Aspiculuris tetraptera has a distinct head-like structure and a tail-like structure. The tail contains a long mitochondrion which extends from within the head almost to the posterior end of the tail. Two bundles of microtubules oriented parallel to the longitudinal axis also extend the length of the tail on either side of the mitochondrion. The head of the spermatozoon contains abundant cytoplasm but no nucleus. The DNA of the spermatozoon is in the tail-like structure where it is associated with an electron-dense sheath and the two bundles of microtubules. The head can put out pseudopodia and it is suggested that they may be involved in locomotion or may be acrosome-like. The tail, which structurally resembles a motile appendage, has not been seen to move. This spermatozoon differs markedly in its structure from all others which have been described.