The Topographical Relationship between the Plane of the Central Pair of Flagellar Fibrils and the Transverse Axis of the Head in Guinea-Pig Spermatozoa

Abstract

Earlier studies on the arrangement of sperm-tail components have suggested that a line through the central pair of fibrils is always perpendicular to the broad face of the flattened sperm head. The principal plane of bending of proximal regions of the tail was therefore assumed to coincide with the transverse axis of the head. The heads of guinea-pig epididymal sperm are flexed 45-50° from the long axis of the tails and are stacked one upon the other in coherent packets. The parallel arrangement of the heads ensures that all of the associated tails will be similarly oriented, and certain planes of section transect heads and tails of the same sperm packet. Taking advantage of this circumstance, it was possible to demonstrate that in quiescent sperm of this species the plane of the central pair is not at 90° to the transverse axis of the head, but is inclined 20-30° off the perpendicular and always in the same direction. Attention is drawn to examples from the literature on cilia and flagella, where there appears to be a similar inclination of the axis of the central pair with respect to external landmarks.