Abstract
The neck region of spermatozoa from the testis and the cauda epididymidis of adult cats were three dimensionally analyzed with an electron microscope. The capitulum consists of a small ventral and a large dorsal portion. The ventral portion is formed after the fusing of longitudinal striated columns 1 and 2, while the dorsal portion, formed of 4+5+6+7in its uppermost end, loses 4 and 7 immediately behind the coalescent knot. The proximal centriole protrudes between 9 and 1+2. The transverse striated columns follow along wall of the proximal centriole. The longitudinal striated columns on the ventral side tend to contact the transverse striated columns on the caudal side, while the longitudinal striated columns on the lateral sides connect with the transverse striated columns on the lateral sides. The ventral portion of the capitulum are coutinuous with the transverse striated columns on the right upper side. Triplets of the distal centriole are not seen in mature spermatozoa. The long axis of the cross section of the flattened head is not always perpendicular to the plane of the central pair of the tail axial filaments, but rotates to both sides within a range of 40°. Ascending toward the head, the two microtubules of the central pair lose the nexin bridge and separate, and their upper portions rotate to both sides within a range of 40°.
