A novel homozygous frameshift variant in DNAH8 causes multiple morphological abnormalities of the sperm flagella in a consanguineous Pakistani family / 亚洲男科学杂志(英文版)

Multiple morphological abnormalities of the sperm flagella (MMAF) is a severe form of asthenozoospermia categorized by immotile spermatozoa with abnormal flagella in ejaculate. Whole-exome sequencing (WES) is used to detect pathogenic variants in patients with MMAF. In this study, a novel homozygous frameshift variant (c.6158_6159insT) in dynein axonemal heavy chain 8 (DNAH8) from two infertile brothers with MMAF in a consanguineous Pakistani family was identified by WES. Reverse transcription-polymerase chain reaction (RT-PCR) confirmed DNAH8 mRNA decay in these patients with the DNAH8 mutation. Hematoxylin-eosin staining and transmission electron microscopy revealed highly divergent morphology and ultrastructure of sperm flagella in these patients. Furthermore, an immunofluorescence assay showed the absence of DNAH8 and a reduction in its associated protein DNAH17 in the patients' spermatozoa. Collectively, our study expands the phenotypic spectrum of patients with DNAH8-related MMAF worldwide.

A recurrent homozygous missense mutation in CCDC103 causes asthenoteratozoospermia due to disorganized dynein arms / 亚洲男科学杂志(英文版)

Asthenoteratozoospermia is one of the most severe types of qualitative sperm defects. Most cases are due to mutations in genes encoding the components of sperm flagella, which have an ultrastructure similar to that of motile cilia. Coiled-coil domain containing 103 (CCDC103) is an outer dynein arm assembly factor, and pathogenic variants of CCDC103 cause primary ciliary dyskinesia (PCD). However, whether CCDC103 pathogenic variants cause severe asthenoteratozoospermia has yet to be determined. Whole-exome sequencing (WES) was performed for two individuals with nonsyndromic asthenoteratozoospermia in a consanguineous family. A homozygous CCDC103 variant segregating recessively with an infertility phenotype was identified (ENST00000035776.2, c.461A>C, p.His154Pro). CCDC103 p.His154Pro was previously reported as a high prevalence mutation causing PCD, though the reproductive phenotype of these PCD individuals is unknown. Transmission electron microscopy (TEM) of affected individuals' spermatozoa showed that the mid-piece was severely damaged with disorganized dynein arms, similar to the abnormal ultrastructure of respiratory ciliary of PCD individuals with the same mutation. Thus, our findings expand the phenotype spectrum of CCDC103 p.His154Pro as a novel pathogenic gene for nonsyndromic asthenospermia.

Novel biallelic loss-of-function mutations in / 亚洲男科学杂志(英文版)

Multiple morphological abnormalities of the sperm flagella (MMAF) is a specific type of asthenoteratozoospermia, presenting with multiple morphological anomalies in spermatozoa, such as absent, bent, coiled, short, or irregular caliber flagella. Previous genetic studies revealed pathogenic mutations in genes encoding cilia and flagella-associated proteins (CFAPs; e.g., CFAP43, CFAP44, CFAP65, CFAP69, CFAP70, and CFAP251) responsible for the MMAF phenotype in infertile men from different ethnic groups. However, none of them have been identified in infertile Pakistani males with MMAF. In the current study, two Pakistani families with MMAF patients were recruited. Whole-exome sequencing (WES) of patients and their parents was performed. WES analysis reflected novel biallelic loss-of-function mutations in CFAP43 in both families (Family 1: ENST00000357060.3, p.Arg300Lysfs*22 and p.Thr526Serfs*43 in a compound heterozygous state; Family 2: ENST00000357060.3, p.Thr526Serfs*43 in a homozygous state). Sanger sequencing further confirmed that these mutations were segregated recessively in the families with the MMAF phenotype. Semiquantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) was carried out to detect the effect of the mutation on mRNA of the affected gene. Previous research demonstrated that biallelic loss-of-function mutations in CFAP43 accounted for the majority of all CFAP43-mutant MMAF patients. To the best of our knowledge, this is the first study to report CFAP43 biallelic loss-of-function mutations in a Pakistani population with the MMAF phenotype. This study will help researchers and clinicians to understand the genetic etiology of MMAF better.

Analysis of DNAH1 gene variant in two infertile males with multiple morphological abnormalities of sperm flagella / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical feature and gene variant for two cases of primary male infertility caused by severe asthenospermia and to analyze the etiology of the disease.@*METHODS@#Genomic DNA of peripheral blood samples of patients and their parents was extracted and gene variant analysis of the patients was conducted by using whole exome sequencing. Suspected pathogenic variant was verified by Sanger sequencing and pathogenic analysis.@*RESULTS@#Whole exome sequencing showed that the DNAH1 gene of patient 1 had two heterozygous variants of c.2016T>G(p.Y672X) and c.6017T>G (p.V2006G). The DNAH1 gene of patient 2 had a homozygous variant of c.2610G>A(p.W870X), which were inherited from his father and mother, respectively. According to American College of Medical Genetics and Genomics standards and guidelines, the c.2016T>G (p.Y672X) and c.2610G>A (p.W870X) varaints of DNAH1 gene were predicted to be pathogenic (PVS1+PM2+PM3+PP3).@*CONCLUSION@#The two patients of multiple morphological abnormalities of the sperm flagella may be caused by DNAH1 gene variant, which has resulted in primary male infertility.

Role of outer dense fiber in multiple morphological abnormalities of the sperm flagella in Akap4 gene defect mice / 中南大学学报(医学版)

To determine the role of outer dense fiber (ODF) in multiple morphological abnormalities of the sperm flagella in Akap4 gene defect mice.
 Methods: Akap4 knock-out (KO) mouse model was established by using gene editing technology. Akap4-KO male mice were identified by genotype. Seven sexually mature male Akap4-KO mice served as an experimental group, and 7 sexually mature wild-type (WT) male mice served as a control group. The changes in body weight and testicular weight were measured. Computer aided sperm analysis (CASA) was used to detect sperm motility. Sperm morphology was detected by modified Periodic Acid-Schif (PAS) staining. The ultra-structure of sperm was observed under the scanning and transmission electron microscope. Sperm flagella associated protein expression and localization were detected by immunofluorescence. Spermatogenesis function of testis was evaluated by HE and PAS staining. Ultra-structure of seminiferous tubules was observed under the transmission electron microscope.
 Results: Akap4-KO mice had no natural fertility. The sperm motility of Akap4-KO male mice was lower than that of WT male mice (8.81% vs 46.02%, P0.01). The longitudinal column of fibrous sheath in Akap4-KO male mice was absent, and the residues of transverse rib remained, which was consistent with the immunofluorescence localization of AKAP3 protein. No. 3 and No. 8 ODF in the principal piece were disordered, which was in consistent with ectopic localization of ODF2 protein.
 Conclusion: Multiple morphological abnormalities of the sperm flagella in mice are resulted from disorder of "9+2" microtubules and the abnormally expanded lumen at the proximal of the principal piece via causing dysplasia of the transverse rib due to Akap4 gene defect, and separation of the ODF of No. 3 and No. 8 via loss of longitudinal column.

Microscopic sperm head damage and abnormalities as heat stress indicators in Australian Merino rams (Ovis aries) in Northern Patagonia, Argentina / Danos e anormalidades microscópicas das cabeças espermáticas como indicadores de estresse por calor em carneiros Merino Australiano (Ovis aries) da Patagônia Norte, Argentina

In Northern Patagonia, the mating season starts on March 15th, when rams are submitted to summer temperatures. Exposure of rams to heat stress increases the prevalence of microscopic damage to spermatozoa, morphological abnormalities, and reductions in fertility. This study assesses the adaptive capabilities of six unshorn and six shorn Australian Merino rams, half of which were treated in a heat chamber for eight hours for five days, gradually reaching a temperature of up to 40 °C. Microscopic damage, abnormalities and ultramicroscopic alterations of the plasma membrane and the acrosome of sperm head were analysed. There were significant differences in the percentage of tailless spermatozoa and proximal cytoplasmic droplets between post-treatment periods. Temperature primarily affected the shorn rams and the sperm heads during spermiogenesis. Submicroscopic alterations were observed when the plasma membrane was present in the anterior segment. These alterations can be intact, waved, or dilated. When the plasma membrane was absent, the acrosome might be intact, dilated, and waved. In addition, the outer acrosomal membrane may completely lose its contents or have a nude nucleus. The plasma membrane assumes a waved shape as a result of the effect of temperature on the epididymis. According to this study, the tailless head, proximal cytoplasmic droplets, and the ultramicroscopic categories studied were robust indicators of semen heat stress. After ten weeks, the sperm head recovered its normal shape. Unshorn rams are better adapted to summer heat stress than shorn ones. Microscopy and transmission electron microscopy alterations have been shown to be excellent indicators of thermal stress in Australian Merino rams and may be useful tools to help sheep farmers choose when to begin the mating season, which will vary depending on the environmental conditions of the summer.(AU)

Na Patagônia Norte, os ovinos têm sua estação de acasalamento iniciada em 15 de março, portanto, ficam sujeitos às temperaturas do verão. A exposição de carneiros a estresse térmico aumenta a prevalência de danos microscópicos e anomalias morfológicas nos espermatozoides, que implica uma redução na fertilidade. Este trabalho avaliou a capacidade adaptativa de carneiros Merino Australiano com lã (N = 6) e tosquiados (N = 6): metade ficou ao ar livre e outra metade foi mantida em uma câmara climática por oito horas, durante cinco dias, chegando gradualmente a uma temperatura máxima de 40 °C. Foram analisados danos microscópicos, anormalidades e alterações ultramicroscópicas da membrana plasmática e do acrossoma da cabeça dos espermatozoides. Os resultados microscópicos confirmaram a existência de diferença significativa na porcentagem de espermatozoides sem cauda e com gota citoplasmática proximal, entre os ejaculados pós-tratamento. A temperatura afetou os carneiros tosquiados, principalmente a cabeça de seus espermatozoides, durante a espermatogênese. Alterações submicroscópicas foram observados na membrana plasmática quando ela estava presente no segmento anterior: quando não intacta, ficava ondulada ou dilatada. Quando a membrana plasmática estava ausente, o acrossoma podia se apresentar ondulado ou dilatado. Além disso, sob efeito do calor, a membrana acrossomal externa pode perder completamente seu conteúdo ou apresentar núcleo desnudo. A membrana plasmática assume uma forma ondulada pelo efeito da temperatura no epidídimo. Depois de dez semanas, a cabeça dos espermatozoides recuperou sua forma normal. Como demonstrado neste estudo, a cabeça sem cauda, as gotas citoplasmáticas proximais e as categorias ultramicroscópicas estudadas são indicadores do efeito do estresse térmico no sêmen, e os carneiros com maior cobertura de lã se adaptam melhor ao estresse por calor. Alterações de microscopia e de microscopia eletrônica de transmissão têm se mostrado excelentes indicadores de estresse por calor em carneiros Merino Australiano e podem ser ferramentas úteis para ajudar criadores de ovelhas a escolher quando começar a época de acasalamento, o que irá variar de acordo com as condições ambientais do verão.(AU)

The expression of the new epididymal luminal protein of PDZ domain containing 1 is decreased in asthenozoospermia / 亚洲男科学杂志(英文版)

Spermatozoa are not mature until they transit the epididymis where they acquire motility and the ability to fertilize an egg through sequential modifications. The epididymis has three functional regions, caput, corpus, and cauda, and the luminal proteins of the epididymis play important roles in the above modifications. However, the proteins with differential enrichment between the caput and cauda are still largely unknown. To reveal the functions of the caput and cauda during sperm maturation, luminal proteins from caput and cauda of mice were analyzed by isobaric tag for relative and absolute quantitation (iTRAQ). Overall, 128 differentially enriched proteins were found, of which 46 were caput enriched and 82 were cauda enriched. Bioinformatic analysis showed that lipid metabolism was active in the caput; while anion- and cation-binding activity and phosphorus and organophosphate metabolism were active in the cauda. A new epididymal luminal protein, the caput-enriched PDZ domain containing 1 (Pdzk1), also named Na+/H+ exchange regulatory cofactor 3 (NHERF3), which plays a critical role in cholesterol metabolism and carnitine transport, was found in the lipid metabolism. Western blotting and immunofluorescence analyses showed that Pdzk1 was expressed in the epididymis but not in the testis, and localized at the middle piece of the sperm tail. Pdzk1 protein level was also reduced in the spermatozoa in case of asthenozoospermic patients compared with that in normozoospermic men, suggesting that Pdzk1 may participate in sperm maturation regulation and may be associated with male infertility. These results may provide new insights into the mechanisms of sperm maturation and male infertility.

ODF4, MAGEA3, and MAGEB4: potential biomarkers in patients with transitional cell carcinoma

Background: This study aimed to evaluate the diagnostic value of outer dense fiber 4 [ODF4], melanoma associated antigen A3 [MAGEA3], and MAGEAB4 mRNAs in transitional cell carcinoma [TCC], using a small amount of cell reverse transcriptase-polymerase chain reaction [RT-PCR] on urinary exfoliated cells

Methods: We recruited a total of 105 suspected TCC patients and 54 sex- and age-matched non-TCC controls. The candidates' genetic expression patterns were investigated with RT-PCR, while reverse transcription quantitative PCR was applied to quantify and compare each mRNA level between cases and control groups

Results: The sensitivity of ODF4, MAGEA3, and MAGEAB4 RT-PCR was 54.8%, 63%, and 53.4%, whereas the specificity was 73.7%, 86%, and 94.7%, respectively. Combining ODF4, MAGEA3, and MAGEAB4 RT-PCR offered a relatively higher sensitivity [83.6%]

Conclusion: RT-PCR with ODF4, MAGEA3, and MAGEAB4 on urinary exfoliated cells could provide clinicians with a promising method to improve TCC diagnosis, especially in the case of gross hematuria and catheterization. The method used here is non-invasive, simple and convenient, and unlike cytology, it does not rely directly on expert professional opinions. These features can be of particular importance to the management of TCC patients in whom regular and lifelong surveillance is required

CatSper in sperm hyperactivation and male infertility: Advances in studies / 中华男科学杂志

The CatSper channel is known as one of the most important Ca²⁺ channels on the cell membrane of mammalian sperm and plays a key role in the motility, hyperactivation and fertilization function of sperm. The CatSper protein, expressed exclusively in the principal piece of the sperm tail, is composed of CatSper1-4 and 5 auxiliary unitsβ,γ,δ and ε, and has an essential part in the functional and structural domains of Ca²⁺as well as in the spatiotemporal regulation of the P-Tyr protein, sperm hyperactivation, efficient sperm migration in the oviduct, egg penetration, and normal fertility. Recent studies show that functional deficiency of CatSper seriously affects sperm function,and the loss of any one of its 9 subunits may lead to male reproductive dysfunction. This paper outlines recent advances in the studies of the CatSperprotein, focusing on its expression, location, structure, and regulation,as well as itsinfluence on sperm hyperactivation and male reproduction.

Expressions of ODF2 mRNA and protein are down-regulated in the sperm of asthenospermia patients / 中华男科学杂志

Objective@#To investigate the mRNA and protein expressions of outer dense fiber 2 (ODF2) in the sperm of the asthenospermia patient and their differences from those in normal healthy men.@*METHODS@#According to the WHO criteria, we collected semen samples from 45 asthenozoospermia patients and 15 normal healthy volunteers. Using computer-assisted sperm analysis (CASA), we divided the semen samples from the asthenospermia patients into a mild, a moderate and a severe group, and determined the mRNA and protein expressions of ODF2 in different groups by RT-PCR and Western blot.@*RESULTS@#Compared with the normal healthy men, the expression of the ODF2 gene showed no statistically significant difference in the mild asthenospermia group (1.112 0 ± 0.525 5 vs 0.688 0 ± 0.372 0, P >0.05) but remarkably decreased in the moderate (0.483 3 ± 0.186 3, P 0.05), but markedly lower than in the moderate (0.145 4 ± 0.053 6, P <0.05) and severe asthenospermia patients (0.122 7 ± 0.045 7, P <0.01), which was consistent with the results of RT-PCR.@*CONCLUSIONS@#Decreased mRNA and protein expressions of ODF2 in the sperm are positively correlated with declined sperm motility of the asthenospermia patient, which is suggestive of the involvement of the ODF2 gene in the regulation of sperm motility.

Outer dense fiber 2 and sperm function: Progress in studies / 中华男科学杂志

Oligoasthenozoospermia, teratozoospermia or low sperm motility is the main cause of male infertility. Low sperm motility can be induced by abnormalities of the sperm tail structure and sperm function. The outer dense fiber protein 2 (ODF2) is a protein fiber maintaining cytoskeleton, as a major component of the mammalian sperm tail and centrosome, and its abnormality is closely related to asthenospermia. Recent studies indicate that ODF2 includes many proteins of the same name and homologous splices located in the sperm centrosomes and spindles of cleaved-embryos, necessary for animal ciliogenesis and associated with sperm capacitation. The features of ODF2 indicate that it is not a single-structural protein. This paper reviews the known functions of ODF2, paving a ground for further studies of the relationship between the ODF2 protein and fertilization.

Pregnancy and birth after intracytoplasmic sperm injection with normal testicular spermatozoa in a patient with azoospermia and tail stump epididymal sperm

Main findings: An intriguing yet perplexing case report of a successful pregnancy and live birth with intracytoplasmic sperm injection using normal testicular sperm, after the finding of azoospermia in the semen analysis and discovering only tail stump abnormal sperm in the epididymis. Case hypothesis: A tail stump sperm defect of genetic origin was suspected. However, after obtaining normal testicular sperm we concluded that obstructive azoospermia, either idiopathic or secondary to multiple minor genital trauma was the plausible scenario. This has rendered the search of previous reports on a similar condition, but none was found. However, it has raised scientific thoughts for future research. Promising future implications: The importance of reporting this case is to alert urologists performing sperm retrieval that healthy and morphologically normal sperm may be found in the testis of azoospermic men with 100% tail stump epididymal sperm. Retrieval of normal testicular sperm obviates the need of a more complex investigation, including sperm electron microscopy. It also offers the possibility of utilizing such gametes for sperm injections rather than abnormal tail stump sperm that may be associated with a poor reproductive outcome.

Successful pregnancy following laser-assisted selection of viable but immotile spermatozoa for intracytoplasmic sperm injection: A report of 2 cases / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the feasibility and clinical application value of selecting viable spermatozoa by noncontact diode laser.</p><p><b>METHODS</b>We obtained immotile spermatozoa from 2 infertile men with obstructive azoospermia or severe asthenospermia and selected viable spermatozoa using a single laser shot at the sperm tail. Those that responded to the laser shot by a curling reaction of the tail were regarded as presumably viable and used for intracytoplasmic sperm injection (ICSI).</p><p><b>RESULTS</b>The mean fertilization rate was 88.89% after ICSI with the laser-selected viable spermatozoa. Both of the embryo transfers resulted in a single pregnancy.</p><p><b>CONCLUSION</b>Noncontact diode laser is a useful alternative for the assessment of sperm viability, which may help to achieve successful pregnancy.</p>

Ouabain and asthenospermia / 中华男科学杂志

Asthenospermia accounts for about 30% of the causes of male infertility. Currently, most drugs for asthenospermia lack specificity and desirable therapeutic efficiency. An insight into the pathogenesis of asthenospermia is important for the development of specific therapies for this disease. The protein Na+/K(+)- ATPase α4 isoform (NKA4) presents in both mature testis tissue and the sperm tail, the absence or reduced activity of which may significantly decrease sperm motility. Ouabain is a natural inhibitor of NKA4, suppressing its activity by specifically binding the ouabain site in it. The hypothalamus and adrenal cortex excrete an ouabain-like steroid hormone called endogenous ouabain (EO), which may be associated with the pathogenesis of asthenospermia by inhibiting the activity of NKA4, affecting Na+/H+ exchange, Na+/Ca2+ exchange and sperm cell membrane potential, and eventually reducing sperm motility.

Eosin Y-water test for sperm function examination / 中华男科学杂志

Based on the principles of the in vitro staining technique, hypotonic swelling test, and water test, the Eosin Y-water test method was developed to simultaneously detect the integrity of the sperm head and tail and sperm membrane structure and function. As a widely used method in clinical laboratories in China, the Eosin Y-water test is methodologically characterized by three advantages. Firstly, both the sperm head and tail can be detected at the same time, which allows easy and comprehensive assessment of membrane damage in different parts of sperm. Secondly, distilled water is used instead of the usual formula solution to simplify and standardize the test by eliminating any potential effects on the water molecules through the sperm membrane due to different osmotic pressure or different sugar proportions and electrolyte solutions. Thirdly, the test takes less time and thus can be repeated before and after treatment. This article focuses on the fundamental principles and modification of the Eosin Y-water test and its application in sperm function examination and routine semen analysis for male infertility, assessment of the quality of sperm retrieved by testicular fine needle aspiration, semen cryopreservation program development, and evaluation of sperm membrane integrity after microwave radiation.

Changes in the ultrastructure of sperm flagella in severe idiopathic asthenospermia patients: observation of 22 cases / 中华男科学杂志

<p><b>OBJECTIVE</b>To observe the ultrastructural changes of sperm flagella in patients with severe idiopathic asthenospermia.</p><p><b>METHODS</b>Using the transmission electron microscope, we examined the ultrastructure of sperm flagella from 22 patients with severe idiopathic asthenospermia.</p><p><b>RESULTS</b>Ultrastructural anomalies were found in all the 22 patients, 6 with partial or complete absence of internal and external dynamic arms in dedicative of primary ciliary dyskinesia, 1 with hyperplasia, hypertrophy and disordered organization of the fibrous sheath usually referred to as dysplasia of the fibrous sheath, and the other 15 with non-specific flagellar anomalies.</p><p><b>CONCLUSION</b>Examination of the ultrastructure of sperm flagella in severe idiopathic asthenospermia patients can help to distinguish congenital from acquired flagellar structural anomalies and give valuable guidance in the treatment.</p>

Dysplasia of the fibrous sheath in human sperm: an update / 中华男科学杂志

The ultrastructural abnormalities of human sperm flagella can cause sperm movement disorders. Dysplasia of the fibrous sheath (DFS) is an autosomal recessive genetic disease. The affected sperm in 95-100% of the patients display short, thick and irregular tails. Transmission electron microscopy can be used to confirm the diagnosis, which reveals gross abnormal flagella, with hypertrophy and hyperplasia of the fibrous sheath, without orderly disposition in longitudinal columns and transversal ribs. The axoneme shows variable distortion or almost complete obliteration. Microtubular doublets may exhibit partial or total lack of dynein arms. The genetic etiology of DFS is not yet clear. DFS does not affect the rates of fertilization and clinical pregnancy in ICSI, but due attention should be paid to the genetic risks in the offspring of the patient.

La calidad espermática evaluada mediante metodologías no convencionales / Sperm quality analysis by non-conventional methodologies

Existen diferentes metodologías para evaluar la calidad seminal, siendo la valoración de la movilidad y de la morfología espermática los indicadores más comúnmente utilizados, sin embargo, los espermatozoides poseen ciertas características que no siempre pueden analizarse a través del examen tradicional. En esta revisión de la literatura se describen algunas metodologías alternativas empleadaspara observar y evaluar las características seminales. La movilidad, la viabilidad y la morfología espermática pueden evaluarse empleando metodologías manuales y análisis asistidos por computador. Otras características evaluables de la biología espermática son la producción de especies reactivas del oxígeno, la calidad mitocondrial y el ADN espermático. Esta revisión demuestra que existe una amplia disponibilidad de metodologías para el análisis seminal, sin embargo, cada día se siguen implementando nuevas técnicas, lo que impactará en el entendimiento de la fisiología espermática. En un futuro estas herramientas diagnósticas podrán incidir en el beneficio de los pacientes con infertilidad.

There are different methodologies for assessing semen quality assessment of mobility and sperm morphology are the most commonly used indicators. However, sperm have certain characteristics that cannot always be analyze through the traditional examination. In this review are describe some alternativemethodologies to observe and assess the seminal characteristics. Motility, viability and sperm morphology can be evaluated using manual methodologies and computational analysis. Other quantifiable characteristics of sperm biology are the production of reactive oxygen species, mitochondrial and DNA sperm quality. Here is shown that there are many methodologies for seminal analysis, however, each day are going to implementing new techniques, which will impact on the understanding of sperm physiology and in the future, they may improve the diagnosis of individuals.

Ultrastructure of the epithelium lining of cauda epididymidis in mongrel dogs / Ultraestrutura do epitélio de revestimento da cauda epididimária em cães sem raça definida

The epithelium lining of cauda epididymidis in mongrel dogs was examined by transmission electron microscopy. The epididymal epithelium is pseudostratified with stereocilia and is composed predominantly of principal and clear cells. Therefore, exist basal and apical cells. The principal and clear cells show features suggesting that they may be preferentially involved in absorptive and secretive functions. These results are compared with previously published data on the cauda epididymidis of other mammalian species, in order to understand the significance of the epididymis in sperm maturation.(AU)

O epitélio de revestimento da cauda epididimária em cães sem raça definida foi examinado através da microscopia eletrônica de transmissão. O epitélio epididimário é pseudoestratificado com estereocílios na borda luminal e é composto principalmente por células principais e claras. Além destes tipos, foi observado algumas células basais e apicais. As células principais e claras apresentaram características ultra-estruturais que sugerem que as mesmas estão envolvidas com funções absortivas e secretórias. Os resultados foram comparados com estudos prévios realizados na cauda do ducto epididimário de outros mamíferos, com o objetivo de melhor entender o papel do epidídimo na maturação espermática.(AU)

Sperm ultrastructure of Mytella (Bivalvia) populations from distinct habitats along the northern coast of São Paulo State, Brazil

Ultrastructural analyses of bivalve spermatozoa are relevant in studies that aim to identify taxonomic traits for the purposes of discriminating species and conducting phylogenetic studies. In the present work, spermatozoa of mussel specimens of the genus Mytella, collected from two populations living in distinct habitats, were examined by electron microscopy. The objective was to identify sperm ultrastructural taxonomic traits that could be used to differentiate Mytella species. The specimens were from populations that live in intertidal zones on the southeast coast of Brazil, either buried in muddy-sand sediment or anchored to rocky substrates. The acrosomal vesicle was conical and long, the axial rod extended from the nucleus to the acrosome, the nucleus was an oblate spheroid with a condensed chromatin, the intermediate portion contained mitochondria encircling a pair of centrioles, and there was a single flagellum. The sperm was of a primitive type. The spermatozoon ultrastructure did not distinguish the specimens buried in muddy-sand sediment from those anchored to rocky substrates. The data suggest that the specimens analyzed, despite living in distinct habitats, belong to the same species, which conchological analyses identified as M. charruana. The presence of an axial rod in their sperm cells supports the inclusion of M. charruana in the subfamily Mytilinae.