Fine structure of late stages of spermiogenesis in Leptocoris trivittatus say (Hemiptera : Corizidae)

Abstract

Although the process of spermiogenesis has been described in many hemipteran species, no such studies at the ultrastructural level have been conducted upon species of the family Corizidae. Thus, the present investigation was initiated to study, by transmission and scanning electron microscopy, spermiogenesis in the boxelder bug, Leptocoris trivittatus (Hemiptera: Corizidae). Although early events, including acrosomal and nebenkern formation, are described, emphasis has been placed upon later events of spermiogenesis, such as acrosomal and mitochondrial transformations, and upon the morphology of the mature spermatozoon. The mature spermatozoon is a filiform structure which is composed of a head, flagellum, and endpiece. The head is comprised of an apical acrosome which extends lateral to a rod-shaped, condensed nucleus. The flagellum contains an axoneme, exhibiting a 9 + 9 + 2 pattern, and paired mitochondrial derivatives. Definitive mitochondrial derivatives are characterized by periodically arranged (45-nm period) cristae and a paracrystalline material within the matrix. Although the mitochondrial derivatives flank the axoneme for most of the spermatozoan length, they are not present in the endpiece of the spermatozoon.