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Nature Communications Aug 2021The sperm head-to-tail coupling apparatus (HTCA) ensures sperm head-tail integrity while defective HTCA causes acephalic spermatozoa, rendering males infertile. Here, we...
The sperm head-to-tail coupling apparatus (HTCA) ensures sperm head-tail integrity while defective HTCA causes acephalic spermatozoa, rendering males infertile. Here, we show that CENTLEIN is indispensable for HTCA integrity and function, and that inactivation of CENTLEIN in mice leads to sperm decapitation and male sterility. We demonstrate that CENTLEIN directly interacts with both SUN5 and PMFBP1, two proteins localized in the HTCA and related with acephalic spermatozoa syndrome. We find that the absence of Centlein sets SUN5 and PMFBP1 apart, the former close to the sperm head and the latter in the decapitated tail. We show that lack of Sun5 results in CENTLEIN and PMFBP1 left in the decapitated tail, while disruption of Pmfbp1 results in SUN5 and CENTLEIN left on the detached sperm head. These results demonstrate that CENTLEIN cooperating with SUN5 and PMFBP1 participates in the HTCA assembly and integration of sperm head to the tail, indicating that impairments of CENTLEIN might be associated with acephalic spermatozoa syndrome in humans.
Topics: Animals; Cell Cycle Proteins; Cells, Cultured; Cytoskeletal Proteins; HEK293 Cells; Humans; Infertility, Male; Male; Membrane Proteins; Mice, Inbred C57BL; Mice, Inbred DBA; Mice, Knockout; Mutation; Protein Binding; Sperm Head; Sperm Tail; Spermatozoa; Teratozoospermia; Mice
PubMed: 34389728
DOI: 10.1038/s41467-021-25227-w -
Advances in Anatomy, Embryology, and... 2016The acrosome, a single exocytotic vesicle on the head of sperm, has an essential role in fertilization, but the exact mechanisms by which it facilitates sperm-egg... (Review)
Review
The acrosome, a single exocytotic vesicle on the head of sperm, has an essential role in fertilization, but the exact mechanisms by which it facilitates sperm-egg interactions remain unresolved. The acrosome contains dozens of secretory proteins that are packaged into the forming structure during spermatogenesis; many of these proteins are localized into specific topographical areas of the acrosome, while others are more diffusely distributed. Acrosomal proteins can also be biochemically classified as components of the acrosomal matrix, a large, relatively insoluble complex, or as soluble proteins. This review focuses on recent findings using genetically modified mice (gene knockouts and transgenic "green acrosome" mice) to study the effects of eliminating acrosomal matrix-associated proteins on sperm structure and function. Some gene knockouts produce infertile phenotypes with obviously missing, specific activities that affect acrosome biogenesis during spermatogenesis or interfere with acrosome function in mature sperm. Mutations that delete some components produce fertile phenotypes with subtler effects that provide useful insights into acrosomal matrix function in fertilization. In general, these studies enable the reassessment of paradigms to explain acrosome formation and function and provide novel, objective insights into the roles of acrosomal matrix proteins in fertilization. The use of genetically engineered mouse models has yielded new mechanistic information that complements recent, important in vivo imaging studies.
Topics: Acrosome; Animals; Female; Fertilization; Gene Expression Regulation; Gene Knockout Techniques; Infertility, Male; Male; Membrane Fusion; Membrane Proteins; Mice; Mice, Transgenic; Mutation; Ovum; Peptide Hydrolases; Sperm Maturation
PubMed: 27194348
DOI: 10.1007/978-3-319-30567-7_2 -
Cells Aug 2020Although sperm head-to-head agglutination has been reported in many mammalian species, the biological significance of this unique sperm-sperm interaction remains largely...
Although sperm head-to-head agglutination has been reported in many mammalian species, the biological significance of this unique sperm-sperm interaction remains largely unknown. Here, we aimed to examine the functional characteristics of agglutinated bovine sperm to determine the possible role of sperm agglutination in the fertilization process. We initially examined temporal changes to the degree of head-to-head agglutination in culture, and found that bovine sperm agglutinated despite the lack of sperm agglutination inducers in medium. Sperm viability and motility were evaluated by SYBR14/PI and JC-1 staining, respectively, to identify the relationship between sperm agglutination and fertilizing ability. Agglutinated sperm had increased motility, viability, and intact mitochondrial function compared with unagglutinated sperm. Furthermore, we found that heparin significantly increased the percentage of unagglutinated sperm, but did not affect viability of both agglutinated and unagglutinated sperm, suggesting that sperm agglutination dictated the viability. In conclusion, agglutinated bovine sperm maintained viability and motility for a longer time than unagglutinated sperm. Thus, we propose that the head-to-head agglutination is a crucial sperm-sperm interaction to ensure the fertilizing ability of sperm.
Topics: Animals; Cattle; Cell Survival; Cells, Cultured; Heparin; Male; Membrane Potential, Mitochondrial; Mitochondria; Sperm Agglutination; Sperm Head; Sperm Motility
PubMed: 32784858
DOI: 10.3390/cells9081865 -
Zygote (Cambridge, England) Oct 2021Sperm morphometric and morphologic data have been shown to represent useful tools for monitoring fertility, improving assisted reproduction techniques and conservation...
Sperm morphometric and morphologic data have been shown to represent useful tools for monitoring fertility, improving assisted reproduction techniques and conservation of genetic material as well as detecting inbreeding of endangered primates. We provide here for the first time sperm morphologic and morphometric data from Cercopithecus neglectus, Cercopithecus cephus, Papio papio and critically endangered Cercopithecus roloway, as well as comparative data from other Cercopithecinae species, i.e. Allochrocebus lhoesti, Mandrillus sphinx and Papio anubis. Following collection from the epididymis, spermatozoa were measured for each species for the following parameters: head length, head width, head perimeter, head area, midpiece length and total flagellum length, and the head volume, ellipticity, elongation, roughness and regularity were then calculated. Our data are consistent with both the general morphology and the morphometric proportions of Cercopithecinae sperm. Some specificities were observed, with C. cephus displaying a narrow head (width = 2.76 ± 0.26 µM) and C. roloway displaying a short midpiece (6.65 ± 0.61 µM). This data set represents an important contribution, especially for Cercopithecus roloway, one of the most endangered monkeys in the world, and further data on additional specimens coupled to data on mating systems and reproductive ecology should allow a better understanding of the mechanisms underlying these morphological differences across primate species.
Topics: Animals; Cercopithecinae; Epididymis; Fertility; Male; Reproduction; Sperm Head; Spermatozoa
PubMed: 33731237
DOI: 10.1017/S0967199421000186 -
Asian Journal of Andrology 2016The spermatozoon is the most diverse cell type known and this diversity is considered to reflect differences in sperm function. How the diversity in sperm morphology... (Review)
Review
The spermatozoon is the most diverse cell type known and this diversity is considered to reflect differences in sperm function. How the diversity in sperm morphology arose during speciation and what role the different specializations play in sperm function, however, remain incompletely characterized. This work reviews the hypotheses proposed to explain sperm morphological evolution, with a focus on some aspects of sperm morphometric evaluation; the ability of morphometrics to predict sperm cryoresistance and male fertility is also discussed. For this, the evaluation of patterns of change of sperm head morphometry throughout a process, instead of the study of the morphometric characteristics of the sperm head at different stages, allows a better identification of the males with different sperm cryoconservation ability. These new approaches, together with more studies employing a greater number of individuals, are needed to obtain novel results concerning the role of sperm morphometry on sperm function. Future studies should aim at understanding the causes of sperm design diversity and the mechanisms that generate them, giving increased attention to other sperm structures besides the sperm head. The implementation of scientific and technological advances could benefit the simultaneous examination of sperm phenotype and sperm function, demonstrating that sperm morphometry could be a useful tool for sperm assessment.
Topics: Cell Shape; Humans; Image Processing, Computer-Assisted; Male; Semen Analysis; Sperm Head; Sperm Motility; Spermatozoa
PubMed: 27678465
DOI: 10.4103/1008-682X.187581 -
Andrology Nov 2019Previous studies suggested that sperm head shape may serve as an effective indicator of semen quality. However, there lacks research with large sample and quantitative...
BACKGROUND
Previous studies suggested that sperm head shape may serve as an effective indicator of semen quality. However, there lacks research with large sample and quantitative measurement.
OBJECTIVES
The objective of this retrospective study was to explore the association between sperm head elongation (Width/Length ratio) and routine semen parameters.
MATERIALS AND METHODS
From January 2012 to December 2017, 63 866 semen samples were collected from male subjects at 18-60 years of age. Sperm head elongation and routine semen parameters (semen volume, sperm concentration, motility, etc.) were examined with computer-assisted semen analysis (CASA) systems in order to evaluate the association between elongation and semen quality.
RESULTS
Logistic and linear regression models showed that the value of elongation is negatively correlated with sperm concentration, total sperm count, progressive motility, total motility, percentage of morphologically normal spermatozoa, and acrosin activity (all p < 0.001).
DISCUSSION
The results suggested that higher value of elongation is generally associated with higher risks of abnormality in semen quality. The importance of elongation may be explained by abnormal acrosin activity in the round-headed spermatozoa, which has been reported to cause failure of natural pregnancy.
CONCLUSIONS
This study provides a new insight into the sperm head shape, which may be used as a complementary parameter in clinical semen examination and academic research.
Topics: Acrosin; Adolescent; Adult; Humans; Infertility, Male; Male; Middle Aged; Retrospective Studies; Semen; Semen Analysis; Sperm Count; Sperm Head; Sperm Motility; Teratozoospermia; Young Adult
PubMed: 30934170
DOI: 10.1111/andr.12619 -
Andrology Mar 2015Mouse mutants that show effects on sperm head shape, the sperm tail (flagellum), and motility were analysed in a systematic way. This was achieved by grouping mutations... (Review)
Review
Mouse mutants that show effects on sperm head shape, the sperm tail (flagellum), and motility were analysed in a systematic way. This was achieved by grouping mutations in the following classes: manchette, acrosome, Sertoli cell contact, chromatin remodelling, and mutations involved in complex regulations such as protein (de)phosphorylation and RNA stability, and flagellum/motility mutations. For all mutant phenotypes, flagellum function (motility) was affected. Head shape, including the nucleus, was also affected in spermatozoa of most mouse models, though with considerable variation. For the mutants that were categorized in the flagellum/motility group, generally normal head shapes were found, even when the flagellum did not develop or only poorly so. Most mutants are sterile, an occasional one semi-sterile. For completeness, the influence of the sex chromosomes on sperm phenotype is included. Functionally, the genes involved can be categorized as regulators of spermiogenesis. When extrapolating these data to human sperm samples, in vivo selection for motility would be the tool for weeding out the products of suboptimal spermiogenesis and epididymal sperm maturation. The striking dependency of motility on proper sperm head development is not easy to understand, but likely is of evolutionary benefit. Also, sperm competition after mating can never act against the long-term multi-generation interest of genetic integrity. Hence, it is plausible to suggest that short-term haplophase fitness i.e., motility, is developmentally integrated with proper nucleus maturation, including genetic integrity to protect multi-generation fitness. We hypothesize that, when the prime defect is in flagellum formation, apparently a feedback loop was not necessary as head morphogenesis in these mutants is mostly normal. Extrapolating to human-assisted reproductive techniques practice, this analysis would supply the arguments for the development of tools to select for motility as a continuous (non-discrete) parameter.
Topics: Acrosome; Animals; Chromatin Assembly and Disassembly; Humans; Male; Mice; Models, Animal; Mutation; Sertoli Cells; Sperm Head; Sperm Motility; Spermatids
PubMed: 25511638
DOI: 10.1111/andr.300 -
Asian Journal of Andrology 2017Dogs have been under strong artificial selection as a consequence of their relationship with man. Differences between breeds are evident that could be reflected in...
Dogs have been under strong artificial selection as a consequence of their relationship with man. Differences between breeds are evident that could be reflected in seminal characteristics. The present study was to evaluate differences in sperm head morphometry between seven well-defined breeds of dog: the British Bulldog, Chihuahua, German Shepherd, Labrador Retriever, Spanish Mastiff, Staffordshire Terrier, and Valencian Rat Hunting dog. Semen samples were obtained by masturbation and smears stained with Diff-Quik. Morphometric analysis (CASA-Morph) produced four size and four shape parameters. Length, Ellipticity, and Elongation showed higher differences between breeds. MANOVA revealed differences among all breeds. Considering the whole dataset, principal component analysis (PCA) showed that PC1 was related to head shape and PC2 to size. Procluster analysis showed the British Bulldog to be the most isolated breed, followed by the German Shepherd. The PCA breed by breed showed the Chihuahua, Labrador Retriever, Spanish Mastiff, and Staffordshire Terrier to have PC1 related to shape and PC2 to size, whereas the British Bulldog, Valencia Rat Hunting dog, and German Shepherd had PC1 related to size and PC2 to shape. The dendrogram for cluster groupings and the distance between them showed the British Bulldog to be separated from the rest of the breeds. Future work on dog semen must take into account the large differences in the breeds' sperm characteristics. The results provide a base for future work on phylogenetic and evolutionary studies of dogs, based on their seminal characteristics.
Topics: Animals; Biological Evolution; Breeding; Cell Shape; Dogs; Male; Multivariate Analysis; Phylogeny; Species Specificity; Sperm Head; Spermatozoa
PubMed: 27751991
DOI: 10.4103/1008-682X.189207 -
Frontiers in Bioscience (Scholar... Sep 2023Analysis of sperm morphology defects (amorphous heads, abnormal acrosome, etc.) is useful for estimating the efficiency of spermiogenesis and sperm maturation. An...
BACKGROUND
Analysis of sperm morphology defects (amorphous heads, abnormal acrosome, etc.) is useful for estimating the efficiency of spermiogenesis and sperm maturation. An advanced paternal age (more than 40 years) is associated with decreasing sperm count and reduced motility; however, there is little information on the effect of aging relating to sperm morphological defects. Moreover, searching for stable combinations of certain morphological defects in the same sperm can be useful for better understanding spermiogenesis. The aim of the study was to investigate age-related changes in sperm morphology and the prevalence of certain combinations of sperm morphological defects in men from the general population.
METHODS
Sperm morphology was assessed in 1266 volunteers from the Russian urban general population in different age groups (18-19, 20-24, 25-29, 30-34, 35-40, and over 40 years old). Two hundred sperm were evaluated from each semen sample (about 250 thousand spermatozoa in total). Sperm defects were classified according to the WHO laboratory manual (WHO, 2010). The total percentage of each sperm defect and the frequency of different combinations of sperm morphological anomalies for each age group were counted. Additionally, a similar analysis was performed for the groups of normospermia and pathozoospermia.
RESULTS
The frequency of coiled and short sperm tails increased in men over 40 years old compared to younger subjects; however, aging did not affect the percentage of morphologically normal sperm. It was shown that the combination of a misshaped head (amorphous, pyriform, and elongated) with a postacrosomal vacuole, acrosome defect, excess residual cytoplasm, or any anomaly of the midpiece or tail in the same spermatozoon were not random combinations of independent solitary defects. The increased frequency of combinations of coiled tails with amorphous, elongated, or vacuolated heads was observed in men older than 40 years. Sperm morphological defects, such as severely deformed heads (pyriform, elongated, and round) were more common in men with pathozoospermia compared to normospermic subjects.
CONCLUSIONS
An age-related impairment in sperm morphology was found. Stable combinations of head defects with anomalies in the acrosome, midpiece or tail suggest that these defects may be the result of a general violation in the morphogenetic mechanism.
Topics: Humans; Male; Adult; Semen; Spermatozoa; Acrosome; Sperm Tail; Semen Analysis
PubMed: 37806952
DOI: 10.31083/j.fbs1503012 -
Archives of Histology and Cytology Dec 2003The formation and organization of a mammalian sperm head occurs through diverse cellular and molecular processes during spermiogenesis. Such cellular events include... (Review)
Review
The formation and organization of a mammalian sperm head occurs through diverse cellular and molecular processes during spermiogenesis. Such cellular events include sequential changes in the nucleus and the acrosome-which is derived from the Golgi apparatus-in concert with prominent bundles of microtubules, the manchette. However, these complex processes are readily impaired by a variety of intrinsic and extrinsic factors, eventually causing various types of male infertility--such as teratozoospermia--which include the deformation of the acrosome and nucleus. In order to comprehend such idiopathic male infertility syndromes, it is important to clarify the mechanism involved in sperm head formation and organization. In addition to the manchette, two key structures in these events are the acroplaxome and the perinuclear theca. The acroplaxome forms the acrosome plate with periodic intermediate filament bundles of the marginal ring at the leading edge of the acrosome, and its nature has recently been characterized. The perinuclear theca, which is located in the perinuclear region in the sperm head, contains not only a cytoskeletal element to maintain the shape of the sperm head but also functional molecules leading to oocyte activation during fertilization. This review discusses recent developments regarding the formation and organization of the mammalian sperm head in relation to its relevant functions.
Topics: Acrosome; Animals; Cell Nucleus; Humans; Male; Mice; Models, Animal; Sperm Head; Spermatogenesis
PubMed: 15018141
DOI: 10.1679/aohc.66.383