During spermiogenesis, the distal centriole forms the axoneme of the sperm tail and becomes a vestige, whilst the proximal remains close to its nucleus and is inherited by the embryo (8,9).
Since the distal centriole gave rise to the sperm axoneme during spermiogenesis, it is logical to suppose that the proximal centriole that is inherited by the embryo could cause aberrant mitosis as both are derived from the same mother centriole in spermatids.
The distal centriole, which will originate spermatozoon flagellum, places following this midpiece.
The midpiece of the mature spermatozoon is a cylindrical and straight structure placed between the nucleus and distal centriole from which the flagellum axonema will originate (Fig.
During spermiogenesis the proximal centriole fuses laterally and orthogonally to the distal centriole to form the basal body, which produces an acentric flagellum (Fig.
The proximal centriole is fused laterally to the distal centriole, creating an acentric basal body (Figs.
Flagella had begun budding from the distal centriole
that was perpendicular to the cell periphery during the stages when the nucleus was spherical and the centrioles lay perpendicular to each other (Fig.
A small cone-shaped acrosomal vesicle projects from the cell surface in close association with the flagellum and associated distal centriole (Fig.
In cross section, the distal centriole possesses radiating, satellite rays that extend to the adjacent cell plasmalemma and trifurcate to form a dense ring (Fig.
The proximal centriole is oriented perpendicular to the distal centriole, from which emanates the axial flagellum.
As the spermatid matures, the mitochondria aggregate posteriorly at the base of the nucleus [ILLUSTRATION FOR FIGURES 5, 7 OMITTED], and eventually fuse to form a ring of four spherical mitochondria enclosing the proximal and distal centrioles [ILLUSTRATION FOR FIGURES 5, 7, 11 OMITTED].
The midpiece region has orthogonally arranged proximal and distal centrioles
. The proximal is about 2 pm long and is connected to the nucleus by electron-dense granular material (Fig.