Morphogenesis of the decapitated and decaudated sperm defect in two brothers

Abstract

The "decapitated sperm" defect, found in both of two sterile brothers, may be assumed to have a genetic origin. The present material suggests that the term "decapitated spermatozoa" is not exact, because detached heads and tails were found in the brothers' ejaculate that could be regarded as "decapitated tails" and "decaudated heads." The present report describes frequent, more or less advanced stages of detachment. Both heads and tails showed a normal structure in which only the postnuclear region was deficient, lacking basal plate and implantation fossa. A break at a different level of the midpiece, and therefore three kinds of separation, were observed. The defect, according to the present research, must originate in the testicular region, whereas the detachment occurs in the epididymis.

Spata6is required for normal assembly of the sperm connecting piece and tight head–tail conjunction

“…Among all reported human cases of acephalic spermatozoa, only several displayed acephalic spermatozoa with full penetrance (∼100% headless), with the rest displaying various percentages of acephalic spermatozoa (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Similarly, mice lacking Odf1 or Oaz3 also display acephalic spermatozoa with partial penetrance (21,22).…”

“…Extensive ultrastructral studies on humans and animals with acephalic spermatozoa suggest that this condition results from defects in formation of the connecting piece of spermatozoa during late spermiogenesis, including failure for the proximal centrioles to attach normally to the caudal portion of the sperm nuclei, leading to abnormal head-midpiece alignment, or a nuclear defect that interferes with formation of the implantation fossa, the normal lodging site for the sperm proximal centriole (16). Aberrant formation of the connecting piece leads to independent development of the sperm heads and flagella, and eventually these structures become separated within the seminiferous tubules or during their transition through the seminal tract as a consequence of increased instability of the head-midpiece junction (16,18).Several features of the human "acephalic spermatozoa," including its uniform phenotype, origin as a systematic alteration of spermiogenesis, unresponsiveness to hormonal treatment, and familial incidence, suggest a genetic origin of this condition (8,16,(18)(19)(20). Mice lacking Odf1, a gene encoding outer dense fiber protein 1, display fragile sperm connecting pieces in addition to a disorganized mitochondrial sheath and defective outer dense fibers (ODFs) (21).…”

“…Several features of the human "acephalic spermatozoa," including its uniform phenotype, origin as a systematic alteration of spermiogenesis, unresponsiveness to hormonal treatment, and familial incidence, suggest a genetic origin of this condition (8,16,(18)(19)(20). Mice lacking Odf1, a gene encoding outer dense fiber protein 1, display fragile sperm connecting pieces in addition to a disorganized mitochondrial sheath and defective outer dense fibers (ODFs) (21).…”

“…Numerous cases of acephalic spermatozoa have been reported in teratozoospermic patients (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). In these patients, the major anomaly lies in headless spermatozoa in the ejaculate, and the headless spermatozoa were initially called "pinhead sperm" because the investigators mistakenly regarded the retained cytoplasmic droplets, which are usually attached to the midprincipal piece junction of the flagella, as the heads of reduced size (8,13,14). Extensive ultrastructral studies on humans and animals with acephalic spermatozoa suggest that this condition results from defects in formation of the connecting piece of spermatozoa during late spermiogenesis, including failure for the proximal centrioles to attach normally to the caudal portion of the sperm nuclei, leading to abnormal head-midpiece alignment, or a nuclear defect that interferes with formation of the implantation fossa, the normal lodging site for the sperm proximal centriole (16).…”

Malformations de l’appareil flagellaire du spermatozoïde impliquées dans l’infertilité chez l’homme

“…Trois types de malformations de l'ancrage flagellaire peuvent être distingués : l'absence d'ancrage ( Figure 3A), la disposition ectopique de l'ancrage ( Figure 3B), la malformation de la pièce connective et la séparation des centrioles [8,9]. Seuls les spermatozoïdes dont les malformations d'ancrage aboutissent à des flagelles isolés de la tête avec une gaine fibreuse immature sont généralement immobiles ( Figure 3A).…”