Anomalies of centriolar derivatives manifest in spermatic flagella and respiratory cilia of the stallion.

Anomalies of centriolar derivatives were identified in ejaculates and testicular and tracheal biopsies of a sterile stallion, using light, scanning, and transmission electron microscopy. LM revealed that over half the sperm population had only a vestigial or no tail, while the rest had tails of variable length and shape. The vestigial tail was represented by its anlage, which was implanted on the nucleus and differentiated up to capitulum and collum stage. The stunted tail had an axoneme and its derivatives, but was short in all tail segments. Regardless of the tail length or shape, virtually all axonemes were devoid of the central tubular complex ("9 + 0" defect). Abnormal tail segmentation was associated with missing or defective flagellar sheaths and a profusion of extraneous dense fibers, which contributed to the knobby, bulbous, or lobuliform tail configurations. The gradient of flagellar anomalies seems associated with the inability of the distal centriole to implant on the plasmalemma, to produce the axoneme, or maintain its growth, and to induce the normal differentiation of periaxonemal structures. In contrast to sperm, the tracheal epithelium displayed moderate changes, which are manifest in circumscribed rarefaction of cilia, increased incidence of compound cilia, and disturbed orientation of cilia regarding the plane of central tubular complex. The tracheal cilia were free of "9 + 0" defect.