• male homozygotes display normal testis size and weight relative to wild-type controls

• in several cases, sperm flagella show a tendency to coil around the nuclei

• elongating spermatids show severe defects in sperm head formation; sperm heads appear completely misshapen rather than elongated

• epididymal spermatozoa are non-functional and characterized by malformed roundish nuclei

• spermatozoa occasionally are encircled by their tail or sometimes are found in large constrictions, indicating cell degeneration

• occasionally, acrosomes are partially detached from the nuclear envelope during final maturation of spermatozoa

• most differentiating spermatids show altered localization of nuclear envelope (NE) components, disorganization of the microtubule manchette, NE lobulation, and severe deformation of the spermatid nuclei

• however, chromatin compaction and positioning of the spermatid centriole/basal body in relation to the posterior NE are normal

• at 15 weeks of age, elongated spermatids are absent in seminiferous tubules; instead, numerous abnormal spermatids with round nuclei are observed

• although early round spermatids appear normal, starting at stage 8 to 9 of the spermatogenic cycle tubules contain a huge number of aberrant roundish spermatids, indicating impaired sperm elongation and shaping

• spermatids lack the rod-like filaments normally found between the NE and the closely associated microtubule manchette

• the manchette, a bundle-like structure normally connected to the posterior NE, is severely disorganized or even completely absent

• microtubules appear loosely assembled and disorganized or, in most cases, dissociated from the NE, indicating impaired assembly and anchorage of the manchette

• in some cases, the manchette is completely absent

• at 15 weeks of age, epididymides lack regular spermatozoa and contain numerous aberrant germ cells with round nuclei in the lumen

• male homozygotes are completely infertile

• in several cases, sperm flagella show a tendency to coil around the nuclei

• elongating spermatids show severe defects in sperm head formation; sperm heads appear completely misshapen rather than elongated

• epididymal spermatozoa are non-functional and characterized by malformed roundish nuclei

• spermatozoa occasionally are encircled by their tail or sometimes are found in large constrictions, indicating cell degeneration

• occasionally, acrosomes are partially detached from the nuclear envelope during final maturation of spermatozoa

• most differentiating spermatids show altered localization of nuclear envelope (NE) components, disorganization of the microtubule manchette, NE lobulation, and severe deformation of the spermatid nuclei

• however, chromatin compaction and positioning of the spermatid centriole/basal body in relation to the posterior NE are normal

• at 15 weeks of age, elongated spermatids are absent in seminiferous tubules; instead, numerous abnormal spermatids with round nuclei are observed

• although early round spermatids appear normal, starting at stage 8 to 9 of the spermatogenic cycle tubules contain a huge number of aberrant roundish spermatids, indicating impaired sperm elongation and shaping

• spermatids lack the rod-like filaments normally found between the NE and the closely associated microtubule manchette

• the manchette, a bundle-like structure normally connected to the posterior NE, is severely disorganized or even completely absent

• microtubules appear loosely assembled and disorganized or, in most cases, dissociated from the NE, indicating impaired assembly and anchorage of the manchette

• in some cases, the manchette is completely absent