All Phenotypes Spata6<tm1a(KOMP)Wtsi> MGI Mouse

oligozoospermia ( J:217662 )

• computer-assisted sperm analyses (CASA) revealed a significantly reduced epididymal sperm (intact spermatozoa plus sperm flagella) count relative to wild-type controls

teratozoospermia ( J:217662 )

• intact spermatozoa represent only ~7%, ~4%, and ~3% of the total sperm cells (intact spermatozoa plus sperm flagella) in mutant testes, caput, and caudal epididymides, respectively, whereas most (96-99%) of wild-type testicular and epididymal spermatozoa appear intact

abnormal sperm flagellum morphology ( J:217662 )

• mutant developing flagella, derived from the distal centrioles, are often misaligned with the developing nuclei/heads, due to lack of connecting piece formation

abnormal sperm connecting piece morphology ( J:217662 )

• TEM analysis of mutant step 15-16 elongated spermatids revealed that the connecting piece is either completely absent or only partially developed, unlike in wild-type spermatids

• major defects include (i) a complete lack of the segmented columns and/or the capitulum and (ii) and partially formed segmented columns

• in either case, no signs of mitochondrial sheath formation are observed

abnormal sperm end piece morphology ( J:217662 )

• in the sperm end piece, mutant spermatozoa display disorganized axonemal microtubules with atypical 8 + 2 or 7 + 2 microtubular compositions instead of the normal 9 + 2 arrangement of axonemal microtubules

• however, the fibrous sheath of the end piece is intact

abnormal sperm midpiece morphology ( J:217662 )

• in the sperm midpiece, mutant spermatozoa show a complete lack of or partially formed mitochondrial sheaths, along with incomplete outer dense fibers (ODFs) and axonemes with missing ODFs and axonemal microtubules

abnormal sperm annulus morphology ( J:217662 )

• absence of mitochondrial sheath formation is always associated with misplacement of the annulus

absent sperm mitochondrial sheath ( J:217662 )

• TEM analysis of mutant step 15-16 elongated spermatids revealed no signs of mitochondrial sheath formation along the outer dense fibers (ODFs) in the mid-piece of the flagellum

detached sperm flagellum ( J:217662 )

• the ratios of free sperm flagella to free sperm heads are drastically increased in mutant testes, caput, and cauda epididymides, relative to those in wild-type controls

• more sperm flagella (93-97%) than sperm heads (14-16%) are present in mutant testes and epididymides relative to wild-type controls

• separated sperm heads are most likely engulfed and absorbed by Sertoli cells

absent sperm head ( J:217662 )

• male homozygotes exhibit acephalic spermatozoa with full penetrance (100% headless)

• intact epididymal spermatozoa with the head still attached to the flagella are extremely rare (<1%)

• mutant headless sperm flagella usually carry enlarged cytoplasmic droplets (CDs) stuffed with mitochondria, never observed in CDs of wild-type epididymal spermatozoa

• TEM analysis of mutant step 15-16 elongated spermatids revealed no defects in either the nucleus or the acrosome

• although separated from the flagella, mutant sperm heads are fully developed and functionally competent, and produce normal offspring when injected into wild-type oocytes

abnormal spermatid morphology ( J:217662 )

• at step 10, mutant spermatids show no signs of segmented column formation in the connecting piece, unlike wild-type spermatids

• at step 11-12, the mutant segmented columns and capitulum are either completely absent or only partially formed and severely disorganized

• at step 13-16, the mutant segmented columns and the capitulum are either completely absent or only partially formed, and the annulus is misplaced

asthenozoospermia ( J:217662 )

• CASA revealed a significantly reduced total motility of mutant epididymal headless spermatozoa relative to wild-type controls

• ~10% of headless sperm flagella from the cauda epididymis show limited progressive motility, with the major waveforms confined only to the end piece instead of the principal piece, as typically observed in wild-type epididymal spermatozoa

abnormal seminiferous tubule epithelium morphology ( J:217662 )

• histology of mutant seminiferous epithelia revealed that fewer sperm heads are aligned along the lumen at stage VII relative to wild-type tubules

• however, testis size, total testis weight, and overall seminiferous tubule morphology are normal

abnormal spermiogenesis ( J:217662 )

• separation of sperm heads from the flagella appears to occur during late spermiogenesis before spermiation

abnormal cauda epididymis morphology ( J:217662 )

• hematoxylin staining of mutant cauda epididymides suggests that fewer sperm heads are present relative to wild-type controls

• mutant cauda epididymides contain mainly sperm flagella bearing enlarged cytoplasmic droplet (CD)-like structures at the mid-principal piece junction

male infertility ( J:217662 )

• adult male homozygotes fail to produce any pups after breeding with fertility-proven adult wild-type females for 6 months

• however, all adult female homozygotes are fertile