AN ELECTRON MICROSCOPE STUDY OF SPERMIOGENESIS IN TELEOST FISH OLIGOCOTTUS MACULOSUS

The fine structure of spermatid differentiation in the sculpin Oligocottus maculosus is described. The chromatin material becomes highly condensed into the form of the mature sperm head before the nuclear envelope conforms to the condensation. Nuclear volume and surface area increase in the early spermatid. Later there is a remarkable reduction of nuclear volume to an estimated 3.0% and of the nuclear surface area to about 19.0% that of the spermatid at its largest size. This great reduction in nuclear size is accompanied by the pinching off of vesicles of nuclear envelope into the cytoplasm. Nuclear pores show a consistent and highly specific arrangement which may have functional significance. No acrosome is formed in this species. Two large mitochondria are segregated in the final stages to a cytoplasmic sleeve surrounding the base of the flagellum. © 1969 Academic Press, Inc.