The cytoskeleton of mammalian spermatozoa

Abstract

The mammalian spermatozoa are endowed with a unique cytoskeleton which consists both of ubiquitous and specific proteins, some of them arising from gene haploid transcription. In the head, a dense perinuclear layer is made of basic proteins (calicin, cylicin, etc) associated with calmodulin and actin remnants. In the flagellum, the axonemal microtubules are mainly composed of glutamylated tubulin isoforms; the periaxonemal outer dense fibers and fibrous sheath are considered as related cytoskeletal structures on the basis of some common polypeptides.

Centriole/basal body morphogenesis and migration during ciliogenesis in animal cells

“…Each doublet has only an outer dynein arm and there is no central pair. Extra-axonemal accessory structures are often found: examples include the outer dense fibres of many sperm (Fouquet and Kann, 1994) and the paraflagellar rod of kinetoplastid protozoa (Maga and LeBowitz, 1999). cilia and flagella generally additionally have two singlet central pair microtubules, radial spokes and dynein arms, which are the molecular motors that enable microtubule sliding and consequent ciliary or flagellar beating.…”

A novel pyruvate kinase (PK-S) from boar spermatozoa is localized at the fibrous sheath and the acrosome

“…The sperm head is connected to the relatively short midpiece of the flagellum where all sperm mitochondria are concentrated surrounding the dense fibres. The principal piece lacks mitochondria but contains the fibrous sheath, a structure typical for mammalian (Fouquet & Kann 1994) and some reptilian (Jamieson et al 1996) spermatozoa. It appears segmented by semi-circular ribs connecting two longitudinal columns thus providing flagellar flexibility.…”

Spef1, a conserved novel testis protein found in mouse sperm flagella

“…During spermiogenesis, the characteristic morphology of the spermatozoon is acquired through the assembly of cytoskeletal components to form the various necessary structures present in mature spermatozoa (Bearer and Friend, 1990;Fouquet and Kann, 1994;Yoshinaga and Toshimori, 2003). These include the perinuclear theca, the acrosome and the flagellum.…”