title: Impaired spermatogenesis in the twitcher mouse: A morphological evaluation from the seminiferous tubules to epididymal transit.
abstract: Spermatogenesis is a complex process of proliferation and differentiation during male germ cell development whereby undifferentiated spermatogonial germ cells evolve into maturing spermatozoa. In this developmental process the interactions between different cell types are finely regulated, hence any disruption in these relationships leads to male infertility. The twitcher mouse, the murine model of Krabbe disease, is characterized by deficiency of galactosylceramidase, an enzyme also involved in the metabolism of the galactosyl-alkyl-acyl-glycerol, the precursor of sulfogalactosyl-alkyl-acyl-glycerol, the most abundant glycolipid in spermatozoa. Twitcher mice are sterile due to alterations of spermatogenesis resulting in the production of spermatozoa with abnormally swollen acrosomes and bent flagella, mainly at the midpiece-principal piece junction. The current study employs light, fluorescence, and electron microscopy to examine the defective spermiogenesis leading to the morphological abnormalities of mature sperm. This study reveals that alterations in germ cell development can be initially detected at the stage VIII and IX of spermatogenesis. The disrupted spermatogenetic process leads to a reduced number of elongating spermatids and spermatozoa in these mutant animals. Electron microscopy analysis demonstrates major acrosomal and chromatin condensation defects in the mutants. In addition, in twitcher mice, the epididymal architecture is impaired, with stereocilia of caput and corpus broken, detached and completely spread out into the lumen. These findings indicate that seminolipid expression is crucial for proper development of spermatocytes and spermatids and for their normal differentiation into mature spermatozoa.
  
  
  BACKGROUND
  GALC: galactosylceramidase; GalAAG: galactosyl-alkyl-acyl-glycerol; SGalAAG: sulfogalactosylalkylacylglycerol; PND: postnatal day; PAS: periodic acid-Schiff stain; TEM: transmission electron microscopy; SEM: scanning electron microscopy; PFA: paraformaldheyde.
authors.affiliation: a Department of Molecular and Developmental Medicine , University of Siena , Siena, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Luddi
authors.affiliation: a Department of Molecular and Developmental Medicine , University of Siena , Siena, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Gori
authors.affiliation: a Department of Molecular and Developmental Medicine , University of Siena , Siena, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Crifasi
authors.affiliation: a Department of Molecular and Developmental Medicine , University of Siena , Siena, Italy.
authors.forename: Camilla
authors.initials: C
authors.lastname: Marrocco
authors.affiliation: a Department of Molecular and Developmental Medicine , University of Siena , Siena, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Belmonte
authors.affiliation: a Department of Molecular and Developmental Medicine , University of Siena , Siena, Italy.
authors.forename: Elvira
authors.initials: E
authors.lastname: Costantino-Ceccarini
authors.affiliation: a Department of Molecular and Developmental Medicine , University of Siena , Siena, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Piomboni
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004822:Epididymis / Q000201:enzymology / Q000648:ultrastructure*; D005698:Galactosylceramidase / Q000235:genetics / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D007248:Infertility, Male / Q000201:enzymology / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology; D007965:Leukodystrophy, Globoid Cell / Q000150:complications / Q000201:enzymology / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D010641:Phenotype; D012671:Seminiferous Tubules / Q000201:enzymology / Q000648:ultrastructure*; D013091:Spermatogenesis; D013094:Spermatozoa / Q000201:enzymology / Q000648:ultrastructure*
chemical_list: D005698:Galactosylceramidase
keywords: Globoid cell leukodystrophy; infertility; seminolipid; spermatogenesis staging; twitcher mouse