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Toxic Responses of the Female Reproductive System
Published in Stephen K. Hall, Joana Chakraborty, Randall J. Ruch, Chemical Exposure and Toxic Responses, 2020
Joana Chakraborty, Maureen McCorquodale
Acrosome reaction releases acrosomal enzymes which allows the sperm cell to pass through the matrix of corona radiata cells and the zona pellucida. The plasma membrane of the spermatozoon then fuses with the oocyte membrane. As soon as this fusion occurs, two drastic changes take place in the oocyte. First, the second meiotic division, which was arrested at the second meiotic metaphase after ovulation, is completed. Second, cortical granules, which were present at the cortex of the egg, release their contents to the exterior of the egg in a process called cortical granule reaction. These materials then act on the zona pellucida to prevent further penetration by other spermatozoa. This process is called the zona reaction. Within two to three hours after spermatozoon-oocyte fusion or fertilization, the second polar body is expelled. The haploid sets of female and male chromosomes lie in the oocyte cytoplasm. At the completion of the fertilization process, two sets of haploid chromosomes, one from the male and the other from the female, produce two pronuclei each of which is surrounded by a distinct nuclear membrane.
LVQ acrosome integrity assessment of boar sperm cells
Published in João Manuel, R. S. Tavares, R. M. Natal Jorge, Computational Modelling of Objects Represented in Images, 2018
Nicolai Petkov, Enrique Alegre, Michael Biehl, Lidia Sánchez
Veterinary experts believe that sperm fertility is related to the state of the acrosome, a cap-like structure that develops over the anterior half of the spermatozoon’s head. It has its own membrane and contains enzymes. As the sperm approaches the oocyte, an acrosome reaction takes place during which the anterior head plasma membrane of the sperm fuses with the outer membrane of the acrosome, exposing the contents of the acrosome. The released enzymes are required for the penetration of sperm through a layer of follicular (cumulus) cells that encase the oocyte. The acrosome reaction also renders the sperm capable of penetrating through the zona pellucida (an extra-cellular coat surrounding the oocyte) and fusing with the egg. For these reasons, veterinary experts believe that a semen sample with a high fraction of acrosome-reacted sperm has low fertilizing capacity and cannot be used for artificial insemination.
Mercury at environmental relevant levels affects spermatozoa function and fertility capacity in bovine sperm
Published in Journal of Toxicology and Environmental Health, Part A, 2019
Elane Fabíola de Sousa Jerônimo da Silva, Daniele Missio, Caroline Silveira Martinez, Dalton Valentim Vassallo, Franck Maciel Peçanha, Fabio Gallas Leivas, Daniela dos Santos Brum, Giulia Alessandra Wiggers
Numerous studies found that Hg increased oxidative stress by induce ROS production and lipid peroxidation thereby disrupting the sperm membrane (Agarwal et al. 2014; Martinez et al. 2014b; Muthu and Krishnamoorthy 2012). The male reproductive system is especially sensible to the increase of oxidative stress (Agarwal et al. 2017). ROS at low concentrations play an important role in the fertilizing capabilities of the spermatozoa stimulating sperm capacitation, hyperactivation, acrosome reaction and, oocyte fusion (Agarwal et al. 2017). However, an imbalance in ROS production disrupts sperm membrane which in turn reduces sperm motility, ability to fuse with the oocyte and directly damages sperm DNA (Agarwal et al. 2014; Heath et al. 2012; Zafar et al. 2015). In the current study, Hg at both concentrations enhanced ROS generation and lipid peroxidation levels and decreased antioxidant capacity in spermatozoa.