Preparation and evaluation of oocytes for intracytoplasmic sperm injection
David K. Gardner, Ariel Weissman, Colin M. Howles, Zeev Shoham in Textbook of Assisted Reproductive Techniques, 2017
Having traversed the cumulus, the spermatozoon undergoes acrosome reaction and binds to the zona pellucida. Sperm-zona pellucida binding is mediated by specific sperm surface receptors. The primary ligand on the zona pellucida, ZP3, specifically binds to the plasma membrane of the acrosomal cap of the intact sperm. The secondary zona ligand, ZP2, binds to the inner acrosomal membrane of the spermatozoon (13–15). One of the inner acrosomal membrane sperm receptors was identified as acrosin (16–18). In order to penetrate the zona pellucida, the spermatozoon utilizes enzymatic as well as mechanical mechanisms. Specific enzymes that are released by the acrosome-reacted spermatozoon allow the invasion of the zona pellucida by local degradation of its components (19, 20). This enzymatic action is assisted by mechanical force generated by vigorous tail beatings that facilitate the penetration of the sharp sperm head (18–22).
Alkaline and Neutral Proteinases Bound to Chromatin: Properties and Functions
Isaac Bekhor, Carol J. Mirell, C. C. Liew in Progress in Nonhistone Protein Research, 1985
As described above, the serine proteinases present in nuclei are alkaline and neutral proteinases, which are bound to chromatin. There is a possibility that these two proteinases may function in the turnover of nuclear proteins. In fact, histones and nonhistone proteins in isolated nuclei or chromatin are rapidly degraded by the proteinases, although in vivo the turnover rates of histones are negligible or extremely slow under most of the physiological conditions.48,49 Marushige et al.32 suggested that during spermatogenesis in trout testis, a chromatin-bound proteinase hydrolyzed the histones bound to DNA, converting the nucleowas the major nonhistonehistone into nucleoprotamine. Zirkin et al.50 found that rabbit sperm nuclei contained an acrosin-like proteinase, suggesting that it removed nuclear protamines from DNA in matured spermatozoa during fertilization. As mentioned above, the increase of the turnover rates of histones was also found in the regenerating rat liver after partial hepatectomy.47
Capacitation, the Acrosome Reaction, and Motility in Mammalian Sperm
Claude Gagnon in Controls of Sperm Motility, 2020
The acrosome is a membrane bounded organelle containing a variety of hydrolytic enzymes (see Reference 1 for a list). At least some of these enzymes, most notably acrosin,47 assist in the penetration of the zona pellucida by weakening its structure. The enzymes are evidently released via a reaction that resembles exocytosis. It was first reported in 1958 by Austin and Bishop,48 and the process was described in 1967 by Barros et al.49 The major events of the acrosome reaction can best be seen in electron micrographs as shown in Figure 2, taken from Suarez et al.50 The first sign of the acrosome reaction, which can occur in human spermatozoa within 1 min of the application of a stimulus, is the apparent decondensation of the acrosomal contents.51 This is followed by the fusion of the plasma membrane in limited areas with the underlying outer acrosomal membrane. Fenestration occurs at the points of fusion, followed by the formation of vesicles comprised of plasma and outer acrosomal membranes.51,52 Acrosomal enzymes may escape by passing between the vesicles or may be exposed after the vesicles are sloughed off. In the latter case, they may be adherent to the exposed surface of the inner acrosomal membrane.53
Differentiation of spermatogonial stem cells by soft agar three-dimensional culture system
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Elham Mohammadzadeh, Tooba Mirzapour, Mohammad Reza Nowroozi, Hamid Nazarian, Abbas Piryaei, Fatemeh Alipour, Sayed Mostafa Modarres Mousavi, Marefat Ghaffari Novin
Acrosin is a serine protease that is used as a marker for spermatogenesis and it is in the acrosome of sperm as an enzyme passive zymogen. Acrosin gene is expressed in both pachytene spermatocyte and round spermatid [38]. In this study, the highest expression of Acrosin gene was observed on day 14 after culture in SACS group, which was significantly higher than that of day 7. Although the expression of Acrosin was higher on day 14 after culture in both gelatin and control groups than day 7, there was no significant difference between two days in two groups. The study of Ventela et al. (2000) showed that low expression of Acrosin in mice was seen in pachytene spermatocytes and after meiosis completion, Acrosin is aggregated in the cytoplasm and lead to strong expression in round spermatid [39]. So, higher expression of Acrosin in SACS group is probably related to a higher number of round spermatid on day 14.
Prediction of male infertility by the World Health Organization laboratory manual for assessment of semen analysis: A systematic review
Published in Arab Journal of Urology, 2018
Amir S. Patel, Joon Yau Leong, Ranjith Ramasamy
Another absolute predictor for male infertility is the detection of globozoospermia on semen analysis. It is a rare but severe form of teratozoospermia, characterised by the presence of round-headed spermatozoa lacking an acrosome [42]. The acrosome contains the digestive enzyme, acrosin, which is essential for binding and penetration of the zona pellucida of the ovum. It also facilitates cervical mucus penetration and intrauterine sperm migration. It also participates in chromatin decondensation in the oocyte [43]. Considering these factors, we can understand how globozoospermic cells have difficulties adhering and fusing with the oocyte membrane, ultimately causing infertility. A microscopic image of globozoospermic spermatozoa can be seen in Fig. 2 [44].
Mapping the human sperm proteome – novel insights into reproductive research
Published in Expert Review of Proteomics, 2023
Mika Alexia Miyazaki, Raquel Lozano Guilharducci, Paula Intasqui, Ricardo Pimenta Bertolla
The consequences of the absence of Testis-expressed protein 101 (TEX101), a validated biomarker of male infertility, were also investigated, and it was noticed that in infertile men with a natural absence of TEX101. This protein is a glycosylphosphatidylinositol-anchored protein (GPI-AP) and in mice was found to be expressed in precursors of adult-type germ cells, spermatogenesis cells, and seminiferous tubules cells in mice [29,30]. Although knockout mice Tex101−/− background presented normal sperm morphology structure and motility, they were not fertile due to failure to induce pregnancy [31]. Other important proteins for fertilizing process were also downregulated, such as Acrosin, Acrosin-binding protein (ACRBP) and Izumo sperm-egg fusion protein 3 (IZUMO3), that participate in the acrosome structure and function, and Zona pellucida-binding protein 2 (ZPBP2), that acts in spermatozoa-zona pellucida binding [32]. IZUMO3 is a protein from protein family IZUMO, exclusively expressed on membrane of cells testes. In mice Izumo3-/- model, fertilization rates were lower compared to the wild-type and heterozygous mutants. Moreover, litter sizes were also significantly reduced. This outcome is likely due to a deficient acrosome [33]