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Zygote (Cambridge, England) Feb 2022Intracytoplasmic sperm injection (ICSI) is an important technique in male infertility treatment. Currently, sperm selection for ICSI in human assisted reproductive... (Review)
Review
Intracytoplasmic sperm injection (ICSI) is an important technique in male infertility treatment. Currently, sperm selection for ICSI in human assisted reproductive technology (ART) is subjective, based on a visual assessment by the operator. Therefore, it is desirable to develop methods that can objectively provide an accurate assessment of the shape and size of sperm heads that use low-magnification microscopy available in most standard fertility clinics. Recent studies have shown a correlation between sperm head size and shape and chromosomal abnormalities, and fertilization rate, and various attempts have been made to establish automated computer-based measurement of the sperm head itself. For example, a dictionary-learning technique and a deep-learning-based method have both been developed. Recently, an automatic algorithm was reported that detects sperm head malformations in real time for selection of the best sperm for ICSI. These data suggest that a real-time sperm selection system for use in ICSI is necessary. Moreover, these systems should incorporate inverted microscopes (×400-600 magnification) but not the fluorescence microscopy techniques often used for a dictionary-learning technique and a deep-learning-based method. These advances are expected to improve future success rates of ARTs. In this review, we summarize recent reports on the assessment of sperm head shape, size, and acrosome status in relation to fertility, and propose further improvements that can be made to the ARTs used in infertility treatments.
Topics: Acrosome; Humans; Infertility, Male; Male; Sperm Head; Sperm Injections, Intracytoplasmic; Spermatozoa
PubMed: 33988119
DOI: 10.1017/S0967199421000307 -
Biochemical and Biophysical Research... Jul 2021Sperm head-to-head agglutination is a well-known known phenomenon in mammalian and non-mammalian species. Although several factors have been reported to induce sperm...
Sperm head-to-head agglutination is a well-known known phenomenon in mammalian and non-mammalian species. Although several factors have been reported to induce sperm agglutination, information on the trigger and process of sperm detachment from the agglutination is scarce. Since hyperactivated motility is involved in bovine sperm detachment from the oviduct, we focused on caffeine, a well-known hyperactivation inducer, and aimed to determine the role of caffeine in sperm detachment from agglutination. Agglutination rate of bovine sperm was significantly decreased upon incubation with caffeine following pre-incubation without caffeine. Additionally, we observed that bovine sperm were detached from agglutination only when the medium contained caffeine. The detached sperm showed more asymmetrical flagellar beating compared to the undetached motile sperm, regardless of whether before or after the detachment. Intriguingly, some sperm that detached from agglutination re-agglutinated with different sperm agglutination. These findings indicated caffeine as a trigger for sperm detachment from the agglutination in bull. Furthermore, another well-known hyperactivation inducer, thimerosal, also significantly reduced the sperm agglutination rate. Overall, the study demonstrated the complete process of sperm detachment from sperm head-to-head agglutination and proposed that hyperactivated motility facilitates sperm detachment from another sperm. These findings would provide a better understanding of sperm physiology and fertilization process in mammals.
Topics: Animals; Caffeine; Cattle; Male; Progesterone; Sperm Agglutination; Sperm Head; Spermatozoa; Thimerosal
PubMed: 34049203
DOI: 10.1016/j.bbrc.2021.05.060 -
Zygote (Cambridge, England) Aug 2011In endeavouring to understand the nature of sperm-oviduct interactions in mammals, attention was focused on experimental models in which fertilization can occur without... (Review)
Review
In endeavouring to understand the nature of sperm-oviduct interactions in mammals, attention was focused on experimental models in which fertilization can occur without a preliminary phase of sperm head binding to the isthmus epithelium. The ovarian endocrine milieu imposed on the oviduct tissues plays an important role in the binding phenomenon, although less so after the time of ovulation. Nonetheless, a sperm suspension introduced into the peritoneal cavity or surgical insemination directly into the oviduct ampulla before ovulation can result in fertilization, as can a surgical model in which the isthmus has been resected and the remaining portions of the duct reanastomosed. Mating or artificial insemination after ovulation in pigs permits rapid sperm transport to the site of fertilization, and the frequency of polyspermic penetration increases with the post-ovulatory age of eggs.Strategies underlying sperm binding were considered, especially in terms of preovulatory sperm storage and suppression of full membranous maturation. These, in turn, raised the problem of how sperm binding in vitro to oviduct cells from prepuberal animals or to cells harvested during the luteal phase of the estrous cycle, or to cells from the ampulla or even the tracheal epithelium, can act to regulate sperm storage and maturation with precision. In an evolutionary perspective, preovulatory binding of diverse populations of cells to the endosalpinx may have developed as a form of fine tuning to assist in sperm selection, to synchronize completion of capacitation with the events of ovulation, and to promote monospermic fertilization by a controlled release of competent gametes.
Topics: Animals; Epithelium; Female; Fertilization; Male; Mammals; Oviducts; Sperm Head
PubMed: 20663263
DOI: 10.1017/S0967199410000341 -
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 Jan 2012This article presents an update on the variable prognostic significance of different sperm pathologies in patients with severe male factor infertility due to morphology... (Review)
Review
This article presents an update on the variable prognostic significance of different sperm pathologies in patients with severe male factor infertility due to morphology and motility disorders. Severe asthenozoospermia is one of the leading causes of male infertility as spermatozoa cannot reach the oocyte and/or penetrate normally. Identifying structural causes of sperm immotility was of great concern before the advent of intracytoplasmic sperm injection (ICSI), because immotility was the limiting factor in the treatment of these patients. In these cases, in vitro methods are used to identify live spermatozoa or stimulate sperm motility to avoid selection of non-viable cells. With these advances, fertilization and pregnancy results have improved dramatically. The identification of genetic phenotypes in asthenozoospermia is important to adequately inform patients of treatment outcomes and risks. The one sperm characteristic that seriously affects fertility prognosis is teratozoospermia, primarily sperm head and neck anomalies. Defects of chromatin condensation and acrosomal hypoplasia are the two most common abnormalities in severe teratozoospermia. The introduction of microscopic methods to select spermatozoa and the development of new ones to evaluate sperm quality before ICSI will assure that ultrastructural identification of sperm pathologies will not only be of academic interest, but will also be an essential tool to inform treatment choice. Herein, we review the differential roles played by sperm components in normal fertilization and early embryo development and explore how assisted reproductive technologies have modified our concepts on the prognostic significance of sperm pathologies affecting the head, neck, mid-piece and tail.
Topics: Humans; Infertility, Male; Male; Prognosis; Reproductive Techniques, Assisted; Sperm Head; Sperm Motility; Sperm Tail; Sperm-Ovum Interactions
PubMed: 22198630
DOI: 10.1038/aja.2011.168 -
Best Practice & Research. Clinical... Dec 2020Spermatozoa are polarized cells with a head and a flagellum joined by the connecting piece. Head integrity is critical for normal sperm function, and head defects... (Review)
Review
Spermatozoa are polarized cells with a head and a flagellum joined by the connecting piece. Head integrity is critical for normal sperm function, and head defects consistently lead to male infertility. Abnormalities of the sperm head are among the most severe and characteristic sperm defects. Patients presenting with a monomorphic head sperm defects such as globozoospermia or marcrozoospermia were analyzed permitting to identify several key genes for spermatogenesis such as AURKC and DPY19L2. The study of patients with other specific sperm head defects such as acephalic spermatozoa have also enabled the identification of new infertility genes such as SUN5. Here, we review the genetic causes leading to morphological defects of sperm head. Advances in the genetics of male infertility are necessary to improve the management of infertility and will pave the road towards future strategies of treatments, especially for patients with the most severe phenotype as sperm head defects.
Topics: Aurora Kinase C; Humans; Infertility, Male; Male; Membrane Proteins; Sperm Head; Spermatogenesis; Spermatozoa; Teratozoospermia
PubMed: 33183966
DOI: 10.1016/j.beem.2020.101473 -
Evolution; International Journal of... Sep 2018Sperm exhibit extraordinary levels of morphological diversification across the animal kingdom. In songbirds, sperm have a helically shaped head incorporating a distinct... (Comparative Study)
Comparative Study
Sperm exhibit extraordinary levels of morphological diversification across the animal kingdom. In songbirds, sperm have a helically shaped head incorporating a distinct acrosomal membrane or "helical keel," the form and extent of which varies across species. The functional significance of this helical shape, however, remains unknown. Using scanning electron microscopy, we quantified inter- and intraspecific variation in sperm head morphology across 36 songbird species (Passeriformes: Passerida). Using phylogenetic comparative methods, we investigated the relationship between sperm head morphology and both sperm swimming speed and the frequency of extra-pair young (EPY). We found that species whose sperm had a relatively more pronounced helical form (i.e., long acrosome, short nucleus, wide helical membrane, and a more pronounced waveform along the sperm head "core") had faster-swimming sperm. We found no evidence of a relationship between interspecific variation in sperm head morphology and EPY, although we did find that among- and within-male variation in sperm head traits were negatively correlated with EPY. Applying principles of fluid mechanics, we discuss how the helical form of the sperm head may influence swimming speed, and suggest that further studies considering aspects of sperm morphology beyond sperm length are needed to improve our understanding of sperm structure-function relationships.
Topics: Animals; Biological Evolution; Male; Microscopy, Electron, Scanning; Phenotype; Phylogeny; Songbirds; Sperm Head; Sperm Motility; Swimming
PubMed: 30015353
DOI: 10.1111/evo.13555 -
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 -
Society of Reproduction and Fertility... 2007The shaping of the mammalian sperm involves the elongation and condensation of the spermatid nucleus, the development of the acrosome, and the transient appearance of... (Review)
Review
The shaping of the mammalian sperm involves the elongation and condensation of the spermatid nucleus, the development of the acrosome, and the transient appearance of the microtubular manchette. F-actin-containing ectoplasmic hoops of Sertoli cells embrace the upper third of the spermatid head during elongation. During acrosomal biogenesis, proacrosomal vesicles derived from the Golgi apparatus, dock and fuse along the acroplaxome, an F-actin/keratin 5-containing cytoskeletal plate. The acroplaxome consists of a bent plate and a marginal ring encircling the spermatid nucleus. It anchors the developing acrosome to the spermatid nucleus. The manchette, consisting of a perinuclear rings with inserted microtubules, lies subjacent to the marginal ring of the acroplaxome. During spermatid elongation, the two overlapping rings reduce their diameter to fit, in a sleeve-like fashion, the decreasing diameter of the spermatid nucleus. The acroplaxome may provide a planar scaffold to modulate exogenous constriction forces generated by Sertoli cell F-actin hoops during spermatid head elongation. The dynamics of the F-actin cytoskeleton, one of the components of the acroplaxome and Sertoli cell hoops, can be regulated by tyrosine kinases, which target cortactin, an F-actin-associated protein. Tyrosine phosphorylation of cortactin correlates with a reduction in the crosslinking properties of F-actin. Phosphorylated cortactin and tyrosine kinase Fer are present in the acroplaxome, thus supporting a role of this F-actin remodelling pathway during spermatid head shaping. Keratin 5, an additional component of the acroplaxome, may also undergo dynamic reorganization during spermatid head elongation. We postulate that the F-actin/keratin 5 cytoskeleton in the acroplaxome may undergo a dynamic reorganization to modulate exogenous shear forces exerted by Sertoli cell F-actin hoops during spermatid head shaping. The acroplaxome-manchette perinuclear rings may reduce their diameter to balance exogenous constriction forces generated by the embracing Sertoli cell F-actin hoops and guide nuclear elongation.
Topics: Actins; Animals; Gene Expression; Gene Expression Regulation; Keratin-5; Male; Mammals; Microscopy, Fluorescence; Microscopy, Phase-Contrast; Sertoli Cells; Sperm Head; Spermatogenesis
PubMed: 17644953
DOI: No ID Found -
Bulletin of Experimental Biology and... Aug 2019The parameters of sperm head in Wistar male rats orally treated with antifungal agent for 48 days during spermatogenesis were studied by the method of image analysis....
The parameters of sperm head in Wistar male rats orally treated with antifungal agent for 48 days during spermatogenesis were studied by the method of image analysis. The degree of roundness (roughness) of sperm head was calculated. Significant differences in morphometric parameters of sperm head, such as length, width, head angle, and roundness were revealed between the treatment and control group. The index of deformation of sperm head in the treatment group rats was 4.93 arb. units. These data indicated microcephaly accompanied by the enlargement of the head, transition of an acute angle to a right angle, and acquiring of a round form. Potential gonadotoxicity was confirmed by the analysis of the functional activity of spermatozoids of male rats (increased count of spermatozoa with head pathology), fertilization ability (enhanced fertility index), and genotoxicity (increased number of chromosomal aberrations polychromatophilic erythrocytes of murine bone marrow). These changes can be responsible for reduced fertility.
Topics: Animals; Antifungal Agents; DNA Damage; Male; Mice; Mutagenicity Tests; Rats; Rats, Wistar; Sperm Head; Spermatozoa
PubMed: 31502128
DOI: 10.1007/s10517-019-04565-2