A FINE STRUCTURE STUDY ON SPERMIOGENESIS IN ARACHNIDA, LEIOBUNUM SP (PHALANGIDA - HARVESTMEN)

Spermatids of the Phalangida, Leiobunum sp., contain Golgi bodies, granular endoplasmic reticulum and centrioles. Spermatids are initially spheroid, but become cup-shaped during spermiogenesis. The nucleus undergoes invagination of one surface during spermiogenesis resulting in the engulfment of electron opaque granules and centrioles by the nucleus. Centrioles loose their morphological identity in late spermatids. Inner and outer nuclear membranes fuse during spermiogenesis to form a pentalaminar nuclear membrane. A membranous organelle, derived from the endoplasmic reticulum and outer nuclear membrane, is situated at one pole of the cup-shaped nucleus. Mitochondria, situated lateral to the membranous organelle in early spermatids, become incorporated into the nucleus. Mature spermatozoa are curved, disk-shaped cells. This data is discussed in terms of the possible functional significance of this unusual form of spermatozoon packaging. © 1969 Academic Press, Inc.