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Genetics and exercise: an introduction
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Claude Bouchard, Henning Wackerhage
Mature sperms and oocytes are haploid cells, carrying only 23 instead of the normal 2 × 23 chromosomes in somatic cells. So how do we get from a normal cell with 46 chromosomes to a gamete? The answer is that this occurs during meiosis, a process by which female and male haploid gametes are generated. Spermatogenesis occurs in the testes and produces sperm in abundance. A subpopulation of these cells, spermatocytes, undergoes two meiotic divisions to form four haploid sperm cells. The process of female gamete production in the ovaries is called oogenesis. It begins during foetal development when thousands of primary oocytes are formed through mitosis. Primary oocytes enter meiosis but their meiotic progression is arrested until puberty with the onset of the menstrual cycle.
Epigenetics in Sperm, Epigenetic Diagnostics, and Transgenerational Inheritance
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Jennifer L. M. Thorson, Millissia Ben Maamar, Michael K. Skinner
A promising approach for the clinical therapy of male infertility is the use of endocrine therapeutics such as FSH, similar to what is currently used in the female (79). While this treatment is successful to stimulate oogenesis in the female, the response in stimulating spermatogenesis is much more variable within the infertile population (80). A recent study demonstrated a genome-wide analysis of DNA methylation identifying a male infertility signature of DMRs present in male infertility patients. Fertile patients were efficiently separated from the infertile population with minimal overlap showing the potential of this molecular biomarker (51). These results further support the potential use of an epigenetic biomarker diagnostic tool for patients with male infertility.
Basic Cell Biology
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
This kind of nuclear division occurs only in the germinal cells (ovary and testis). In the testis during meiosis, each member of a paired chromosome duplicates, and the duplicated members come to lie side by side in a four-stranded configuration. The successive nuclear divisions result in the formation of four sperm, each with a haploid set of chromosomes (half of the parent cell). During meiosis, the first nuclear division is a mitotic one in which each daughter cell receives an identical set of diploid chromosomes. The second nuclear division is a reduction division in which each daughter cell contains only the haploid set of chromosomes. Diagrammatic representations of meiosis in the testis and ovary are shown in Figures 2.3 and 2.4. In the testis, spermatogonia divide by mitosis to form primary spermatocytes, which undergo reduction division to form spermatids. Spermatids have a haploid set of chromosomes. The spermatids undergo a maturation process to form spermatozoa. The entire process of the formation of spermatoza is called spermatogenesis. The basic process of meiosis in the female is the same, except that each oocyte gives rise to only one functional egg, whereas each spermatocyte produces four functional spermatozoa. The process of forming the functional egg is called oogenesis.
The decellularized ovary as a potential scaffold for maturation of preantral ovarian follicles of prepubertal mice
Published in Systems Biology in Reproductive Medicine, 2021
Sanaz Alaee, Raheleh Asadollahpour, Abasalt Hosseinzadeh Colagar, Tahereh Talaei-Khozani
To assess the functionality of follicles cultured in 2D and 3D conditions, their steroidogenic and oogenic activities were evaluated. Our data showed that in the decellularized ovarian scaffold, mature follicles secrete E2 and P4 and can undergo normal growth and development to produce mature, meiotically competent oocytes. Secretion of estrogen from follicular somatic cells causes further growth of the follicles as observed in our evaluation of follicular growth and diameter. E2 promotes antrum formation, gap junction development, and prevention of atresia in primate follicles in vitro (Ting et al. 2015; Farman et al. 2015). P4 acts on preantral follicles and promotes follicle survival (Ting et al. 2015). P4 as an anti-apoptotic factor was observed in granulosa cells of large antral follicles (Peluso 2006; Puttabyatappa et al. 2013). Therefore, our results confirmed that the ovarian ECM provides a platform for structural support, the growth of follicles’ and steroidogenesis, and sequestrates paracrine regulatory factors that are involved in folliculogenesis and oogenesis.
Effects of three conventional insecticides on life table parameters and detoxifying enzymes activity of Pulvinaria aurantii Cockerell (Hemiptera: Coccidae)
Published in Toxin Reviews, 2021
Mohammad Fazel Hallaji Sani, Bahram Naseri, Hooshang Rafiee-Dastjerdi, Sirus Aghajanzadeh, Mohammad Ghadamyari
Significant decrease in the fecundity and fertility were also revealed when early instars of P. aurantii were treated with tested insecticides. Several hypotheses can be suggested to explain these results. First, chronic exposure to these chemicals could affect oogenesis (Willard et al. 2006). Second, exposure to insecticides could indirectly alter the hormonal status of the insects and could affect the capacity of egg production; as Bownes et al. (1988) reported that the increase of ecdysone reduces egg production by Drosophila melanogaster Meigen (Diptera: Drosophilidae). In other studies, a decrease in either the number of eggs laid by Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) (Abdel-Aal 2012) or the percentage of the eggs hatched in Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) (Moadeli et al. 2014) was observed when the insects were treated with pyriproxyfen at fourth instars or eggs, respectively.
Impact of paternal transmission of gamma radiation on reproduction, oogenesis, and spermatogenesis of the housefly, Musca domestica L. (Diptera: Muscidae)
Published in International Journal of Radiation Biology, 2021
Adult males and females of F1 progeny (resulted from main combination) and other unirradiated were examined ultrastructurally. The reproductive potential was investigated at the level of oogenesis and spermatogenesis. As illustrated in Figure 4, radiation with 5 Gy showed signs of degeneration process in the vitellogenic region and weakness of the ovarian sheath (Figure 4(B)). Lysis and degeneration of oocytes, vacuoles, and appearance of degenerated nurse cells were the most distinguished signs of irradiation with 10 Gy (Figure 4(C)). Damage and lysis of oocytes were detected in females of 15 Gy group, disappearance of well-developed nurse cells, shrinkage of the nucleus, and disappearance of nucleus with condensed chromatin were the most visible signs of this damage (Figure 4(D)). In contrast, the ovarian development of the unirradiated group (Figure 4(A)), exhibit a well-developed nurse cells, ideal vitellogenic region with intact ovarian sheath, and oocytes nearly occupied most of it.