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

reproductive system phenotype ( J:334562 )

N	• adult females produce litters of normal size

abnormal meiotic spindle morphology ( J:334562 )

• males show defects in the assembly and function of the meiotic spindle

increased male germ cell apoptosis ( J:334562 )

• immunohistochemical staining of cleaved-caspase 3 and 9 showed a 2.6-fold increase in the number of apoptotic germ cells per seminiferous tubule

• increase in apoptosis occurs primarily in metaphase and early anaphase spermatocytes

abnormal seminiferous tubule epithelium morphology ( J:334562 )

• large areas of the seminiferous epithelium are devoid of germ cells and/or display a lacy appearance, indicative of recent germ cell loss

seminiferous tubule degeneration ( J:334562 )

• PAS-stained testis sections showed vacuoles in the seminiferous epithelium

small testis ( J:334562 )

decreased testis weight ( J:334562 )

• adult males show a 36.7% reduction in testis weight relative to wild-type controls

• however, adult body weight is normal

abnormal spermatogenesis ( J:334562 )

• earliest defect in spermatogenesis is detected during metaphase of meiosis I

• spermatogonia and primary spermatocytes up to and including prophase I appear normal

azoospermia ( J:334562 )

• total daily sperm production per testis is reduced by 99.4%

• epididymal sperm content is reduced by 99.7%; rare cells found in the epididymis are prematurely sloughed spermatocytes and round spermatids

abnormal acrosome morphology ( J:334562 )

• percentage of cap-phase spermatids with abnormal acrosome localization and/or morphology is significantly increased

abnormal acrosome assembly ( J:334562 )

• during the Golgi phase, early round spermatids (step 2-3) exhibit PAS-positive pro-acrosomal vesicles that are ectopically distributed throughout the cytoplasm

• in many spermatids, pro-acrosomal vesicles adhere to multiple ectopic sites on the nuclear membrane, including at the caudal pole

• as spermatids develop into the cap phase (step 4-7), sites of supernumerary acrosome formation are observed

• multi-lamellar bodies are frequently seen from the cap phase onwards, indicating that the Golgi apparatus and/or the endocytic pathway may be overactive

• during the acrosome phase (step 8-12), multiple acrosome compartments are still observed in addition to a loss of nuclear membrane integrity

• EM showed that, starting in the Golgi phase, docking of acrosomal vesicles is associated with an abnormally deep nuclear membrane invagination, not observed in wild-type spermatids

abnormal sperm nucleus morphology ( J:334562 )

• spermatid nuclei exhibit severely disrupted membrane integrity at the onset of nuclear elongation in step 9

abnormal spermatid morphology ( J:334562 )

• abnormally large round spermatids or, rarely, bi-nucleated spermatids are observed

• round spermatids often show abnormally large nuclei containing multiple nucleoli, or the presence of multiple nuclei within the same cell

• spermatid nuclei show severe disruption of membrane integrity; this is first noted as deep invaginations of the nuclear membrane caused by the overlying acrosome and progresses to ruptured nuclei after manchette formation

abnormal manchette morphology ( J:334562 )

• percentage of step 12 spermatids with abnormal manchettes, including ectopic, abnormally dense and excessively elongated manchettes, is significantly increased

• the manchette is partially or completely detached from most elongating spermatid nuclei

abnormal manchette assembly ( J:334562 )

• manchette microtubules over-accumulate resulting in abnormally wide and dense manchettes

• immunostaining showed an increase in manchette microtubule number and polyglutamylated tubulin

abnormal manchette disassembly ( J:334562 )

• manchettes are still present in step 14 spermatids, unlike in wild-type spermatids where manchettes are disassembled

ectopic manchette ( J:334562 )

• an increased number of step 12 spermatids exhibit ectopic manchettes

elongated manchette ( J:334562 )

• by step 11, manchettes are excessively long relative to those seen in wild-type males

abnormal male meiosis ( J:334562 )

• metaphase spermatocytes frequently contain misaligned chromosomes and/or a wider dispersion of chromosomes at the metaphase plate

• on average, 39% of meiotic cells contain misaligned chromosomes and 18% are abnormally dispersed

• germ cells that progress to anaphase commonly exhibit uneven chromosome segregation

• meiosis defects result in round spermatids with abnormal phenotypes, including sister cells sharing a single nucleus, which crosses the intercellular bridge, binucleated spermatids, and abnormally large nuclei

arrest of male meiosis ( J:334562 )

• many pyknotic PAS-positive/caspase-positive metaphase I and early anaphase I spermatocytes arrest in stage XII and persist in stage I tubules, indicating a meiosis arrest followed by germ cell loss

• a single nucleus crossing the intercellular bridge between sister round spermatids is frequently observed, suggesting a failure of metaphase/anaphase and incomplete cytokinesis

• rare binucleated spermatids likely arise as a result of complete anaphase followed by unsuccessful cytokinesis

abnormal spermiogenesis ( J:334562 )

• round spermatids show abnormal acrosome development and fail to elongate

• spermatid nuclear integrity is severely disrupted at the onset of nuclear elongation in step 9

• after the initiation of spermatid elongation, spermatids exhibit a loss of nuclear membrane integrity, ultimately leading to cell death and a virtual absence of sperm

• nuclear envelope breakages are first noted in early elongating spermatids; at later developmental stages, nuclear envelopes become increasingly degraded with ruptured nuclear membranes most frequently seen at the caudal pole

• DNA condensation is only initiated in isolated regions; at later developmental stages, most spermatids contain no discernible nucleus and show an increase in DNA damage, as determined by gamma-H2AX staining

male infertility ( J:334562 )

• adult males (10 weeks of age or older) are sterile

• however, male mating behavior is normal