Dynamic changes in the cytoskeleton during human spermiogenesis

Objective: To investigate the structural changes in the cytoskeleton (microtubules, microfilaments) and examine the expression of centrosomal functional proteins during human spermiogenesis. Design: Immunofluorescent staining of human spermiogenic cells. Setting: University hospital and IVF clinic. Patient(s): Human testicular tissues were obtained by testicular sperm aspiration (TESA) under informed consent. Three cases of obstructive azoospermia, with confirmed normal spermatogenesis, were examined. Intervention(s): Spermatogenic cells were fixed with microtubule-stabilizing buffer. Immunocytochemical detection of microtubules, microfilaments, and centrosome was performed using monoclonal antibodies against α- and β-tubulin, phalloidin, and functional centrosomal proteins. Main Outcome Measure(s): Samples were examined using epifluorescence and laser scanning confocal microscopes. Result(s): During the Sb2 period, microtubules formed the manchette structure, which extended from the equator of the nucleus through the cytoplasm. Microfilaments were organized in the periacrosamal region during spermiogenesis (Sa to Sd). Although centrin was observed throughout the spermiogenic period, γ-tubulin was detected only in the Sb2 period. Conclusion(s): Dynamic cytoskeletal movement was observed during human spermiogenesis. Cytoskeletal rearrangements in the Sb2 period appear to play important roles in the morphologic changes that occur during human spermiogenesis. Studies of the cytoskeletal system during spermiogenesis may help identify some causes of male infertility (e.g., teratozoospermia, maturation arrest).