title: Quantitative ultramorphological evaluation of swim-up spermatozoa used in human in vitro fertilization and transcervical intrauterine insemination.
abstract: Ultramorphological changes that occur on the sperm head during in vitro incubation of human spermatozoa was investigated using transmission electron microscopy (TEM). Motile spermatozoa that swim-up were processed for TEM. Washed but unincubated sperm heads had all of the fine structural characteristics of normal spermatozoa: intact plasma membrane, acrosome, equatorial segment, postacrosomal sheath, subacrosomal space filled with fine granular material, dense nucleus containing conspicuous nuclear vacuoles of differing sizes and numbers, and faintly discernible nuclear membrane. The procedure of washing and centrifugation did not alter the structural integrity of spermatozoa. Any evidence of ultramorphological changes in the incubated spermatozoa appeared to be confined to the surface of the anterior two-thirds of the sperm head. These changes were characterized by detachment of plasma membrane, fusion of plasma and acrosomal membranes, vesiculation of membranes, and exposure of acrosomal contents. There was a significant (p less than 0.001) time-dependent increase in the proportion of spermatozoa with such changes. The anterior border of these denuded sperm heads were bound only by the acrosome that appeared as electron-dense granular material on the outer margin and attached on its inner border to the inner acrosomal membrane. Furthermore, in vitro incubation of washed spermatozoa did not lead to any time-dependent degenerative changes.
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007315:Insemination, Artificial; D008297:Male; D008854:Microscopy, Electron; D013075:Sperm Capacitation; D013077:Sperm Head / Q000648:ultrastructure; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure*