Centrosome Reduction during Mouse Spermiogenesis

Abstract

The sperm does not contribute the centrosome during murine fertilization. To determine the manner in which a functional centrosome is reduced, we have studied centrosome degeneration during spermiogenesis of mice. The round spermatids display normal centrosomes consisting of a pair of centrioles along with gamma-tubulin containing foci. However, they do not seem to organize microtubules. Elongating spermatids display gamma-tubulin spots in the neck region, while microtubules are organized from the perinuclear ring as the manchette. Electron microscopic studies using immunogold labeling revealed that gamma-tubulin is mainly localized in the centriolar adjunct from which an aster of microtubules emanates. Microtubules repolymerized randomly in the cytoplasm after nocodazole treatment and reversal. gamma-Tubulin dissociates from the neck region and is discarded in the residual bodies during spermiation. The distal centriole degenerates during testicular stage of spermiogenesis, while the proximal centriole is lost during epididymal stage. Loss of centrosomal protein and centrioles in mouse sperm further confirm the maternal inheritance of centrosome during murine fertilization.

Regulated expression of the ubiquitin protein ligase, E3Histone/LASU1/Mule/ARF‐BP1/HUWE1, during spermatogenesis

“…Mutation of testis specific protease USP26 results in male infertility (Paduch et al, 2005). In addition to these gene inactivation studies, other reports indicate that ubiquitination may be involved in the reduction of mitochondria (Sutovsky et al, 1999(Sutovsky et al, , 2000 and the centrosome (Manandhar et al, 1998) during spermiogenesis.…”

Sperm dysfunction and ciliopathy

“…Both proximal and distal centrioles are present in elongating spermatids, but the distal centriole and its associated structures are degenerated in mature sperm in mouse [64]. Human sperm have intact proximal centrioles, but the distal centrioles are largely degenerated [65].…”

Procedure for Bovine ICSI, not Sperm Freeze-drying, Impairs the Function of the Microtubule-organizing Center

“…During fertilization in most mammalian species, the centrosome brought into an oocyte by a spermatozoon plays a critical role in assembly of the microtubule network that brings both male and female pronuclei to the center of the newly formed zygote, as reported in humans [2], rhesus monkeys [3], rabbits [4], pigs [5] and cattle [6]. Interestingly, paternal inheritance of the MTOC does not occur in the mouse [7] and rat [8], and the microtubule network developed from multiple cytoplasmic asters, instead of a single sperm-aster, is involved in the migration of pronuclei [9].Freeze-drying has been proposed as an alternative method to preserve mammalian spermatozoa [10], although freeze-dried (FD) spermatozoa after rehydration lose their motility and application of intracytoplasmic sperm injection (ICSI) technique is necessary. Rodent spermatozoa can be stored practically at refrigeration temperatures [11][12][13].…”

“…During fertilization in most mammalian species, the centrosome brought into an oocyte by a spermatozoon plays a critical role in assembly of the microtubule network that brings both male and female pronuclei to the center of the newly formed zygote, as reported in humans [2], rhesus monkeys [3], rabbits [4], pigs [5] and cattle [6]. Interestingly, paternal inheritance of the MTOC does not occur in the mouse [7] and rat [8], and the microtubule network developed from multiple cytoplasmic asters, instead of a single sperm-aster, is involved in the migration of pronuclei [9].…”