Abstract

Spermiogenesis and mature sperm of the common turkey (Meleagris gallopavo) and rock pigeon (Columba livia) were studied using electron microscopy. Spermiogenesis in turkey was found to be started with the formation of a subacrosomal vesicle originates in between the double layer of the nuclear envelope. Another vesicle originates from Golgi body to form acrosomal cap. In pigeon, a large acrosomal vesicle attached to the nucleus and contain an acrosomal granule starts the spermiogenesis. Turkey sperm represents non-passerine bird pattern in that it has a long perforatorium which is a solid, well defined structure covered anteriorly with the acrosome and lies in a nuclear invagination, the endonuclear canal. Perforatorium was not found in pigeon spermatozoon and the endonuclear canal is vestigial. Chromatin condensation and nuclear elongation, which are specific features of spermiogenesis are found in both species. Proximal and distal centriole found to be perpendicular to each other in the turkey and pigeon however the distal centriole in turkey is longer. In pigeon, large numbers of mitochondria cover most of the tail. A mitochondrial sheath was also found in turkey sperm tail with elongated and larger constituents. An amorphous sheath instead of a fibrous sheath is found in the sperm tail of turkey while pigeon sperm tail contains dense fibers only. These findings were attributed partly to the species differences and may be also attributed to the fact that turkey is non-passerine while pigeon is a passerine bird.

Key words: Ultrastructur, Spermiogenesis, Meleagris gallopavo, Columba livia