Ultrastructure of the Spermatozoon of the Lizard Cnemidophorus sexlineatus (Sauria: Teiidae)

Abstract

Spermatozoa of Cnemidophorus sexlineatus were studied by transmission and scanning electron microscopy. The cell is filiform, 62 micrometers long and 0.6 micrometers in diameter. Organization of the midpiece with five sets of ring structures and mitochondria (designated rsl/mil... rs5/mi5), terminated by an annulus, an, is homologized to spermatozoa of other species of lizards, notably Old World Lacerta. An acrosomal filament composed of 8 nm fibers is present in spermatozoa isolated from the ductus deferens. The nucleus has two curves which offset the head of the sperm from the cell axis. The flagellar fibrous sheath begins at rs3 and enwraps the flagellum to 1 micrometers above its terminus. The flagellar axoneme is of the typical 9-doublet + 2-central-singlet microtubule construction. The A-tubules contain electron-dense material. Microtubule-fibrous sheath connectives and fibrous sheath-cell membrane connectives were observed. Extracellular tubules attend maturing spermatozoa in the ductus deferens. A maturation process is suggested for male sex cells in the female tract. Spermatozoa in the ductus deferens are characterized by spatulate acrosomes and bends of the midpiece at rs2/mi2. Spermatozoa flushed from the oviduct/uterus have pointed acrosomes and are straight in the midpiece