Mouse Mutations with Endocrine Functional Consequences
John P. Sundberg in Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
This autosomal recessive locus was identified in the C57BL/6J inbred strain at the Jackson Laboratory from pedigree records for infertile matings and reported in 1988.41 The jsd gene has been shown to be on Chromosome 1 near ldh-1 and continues to be maintained on the C57BL/6J background. Only males are affected and histological sections of adult testes are characterized by presence of rare spermatogonia and absence of any further stages of spermatogenesis. Androgen levels were found to be normal, while FSH levels were elevated for several months. Additional studies showed that jsd/jsd seminiferous tubules experience a single wave of spermatogenesis coincident with the peripubertal period that ends about 7 to 8 weeks of age. Adults do not ever again show spermatogenesis, perhaps due to defective paracrine mitogenic factors produced within the seminiferous tubules. No hair or skin defects are recorded for these mutant mice.
Basic Cell Biology
Kedar N. Prasad in 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.
Cryptorchid-Induced Changes in Spermatogenesis and Fertility
Tom O. Abney, Brooks A. Keel in The Cryptorchid Testis, 2020
Nearly a decade later Hadziselimovic et al.33 provided evidence which seemed to indicate that damage to the spermatogenic potential of the cryptorchid testis may occur much earlier than previously thought. In this study electron microscopic evidence was presented which indicated that in the 1st year of life no morphological alterations of the spermatogonia were apparent in normal or cryptorchid testes. However, by the 2nd year of life a decrease in the volume density of the spermatogonia was found. Corresponding with this decrease was an increase in the volume density of degenerating cells. Based on these investigations, the authors concluded that the optimal time for surgical correction of cryptorchidism is in the 2nd year of life.33 It would therefore appear that some histological alterations occur in cryptorchid testes as early as 2 to 5 years of age.3
Eco-friendly postharvest irradiation strategy with 131I isotope for environmental management of populations of migratory locust, Locusta migratoria
Published in International Journal of Radiation Biology, 2023
Noura A. Toto, Marian Malak, Nessrin Kheirallah, Ahmed M. Eldrieny, Lamia M. El-Samad, John P. Giesy, Abeer El Wakil
Cysts in testicular follicles from control insects include different phases of spermatogenesis and spermiogenesis that were clearly observed (Figure 2(a)). Connective tissue and the trachea envelope held cysts together. Each follicle consists of a few apical cells followed by a succession of consecutive zones containing spermatogonia, spermatocytes, spermatids and spermatozoa, respectively (Figure 2(a)). In semi-thin micrographs, spermatogonia appeared as spherical cells with circular nuclei. Germ cells at the proximal end of the testicular follicle first divide by mitosis to form spermatocytes, which are larger than spermatogonia. Later, via meiosis, spermatids are formed from tiny spermatocytes (spermiogenesis) in the central part of the follicles. Nuclei of spermatids are spherical and are substantially smaller than spermatocytes nuclei. Finally, spermatids in the follicle’s proximal area differentiate into spermatozoa, which are orientated in the same direction and are approximately parallel (Figure 2(b–d)).
Three major reasons why transgenerational effects of radiation are difficult to detect in humans
Published in International Journal of Radiation Biology, 2023
Nori Nakamura, Noriaki Yoshida, Tatsuya Suwa
In the mouse, Type A spermatogonia were thought to be similar to renewable stem cells (As) and give rise to differentiated spermatogonia (Type A1 to A4), followed by Type B spermatogonia and then spermatocytes. However, later studies showed that as cells are further divided into three types, a single-cell type (Ais: isolated), a connected two-cell type (Apr: paired), and a connected 4-, 8- or even 16-cell type (Acl: clonal). Currently, Ais cells are regarded as being SSCs while Apr and Acl cells are undifferentiated progenitors, and the number of Acl cells is 2 to 50 times larger than Ais or Apr cells depending on the epithelial stages of the seminiferous tubules (Erickson 1981). Dose survival data which was determined microscopically in toto (whole mount) 1 to14 days after irradiation showed that Acl cells are radiosensitive, especially at doses below 1 Gy, whereas Ais cells are quite resistant (Figure 9A). The results are remarkable because many other studies which used cross-sectional approaches repeatedly indicated that mouse spermatogonia were highly sensitive to the killing effect of radiation and that the dose-survival responses had no shoulder. Such observations were probably made primarily on Acl cells.
Atrazine neural and reproductive toxicity
Published in Toxin Reviews, 2022
Hamidreza Sadeghnia, Sara Shahba, Alireza Ebrahimzadeh-Bideskan, Shabnam Mohammadi, Amir Mohammad Malvandi, Abbas Mohammadipour
Sperm is produced from germinal cells through spermatogenesis. The primary cell involved in spermatogenesis is spermatogonia (Fani et al. 2018). Fani et al. (2018) showed that atrazine dysregulates the process of spermatogenesis (Fani et al. 2018). This study revealed that atrazine exposure resulted in increased apoptosis in spermatogonia and primary spermatocytes and reduced sperm quality in mice. Another study reported that atrazine administration (300 mg/kg) to rats decreases sperm motility and counts by 25.8% and 27.6%, respectively (Kale et al. 2018). An increase in apoptotic cells number may be due to oxidative stress induced by atrazine. According to Kale et al. (2018), atrazine-induced oxidative damage in testis is associated with cyclooxygenase-2 (COX-2), an enzyme involved in various pathological conditions, and able to induce oxidative stress (Chae et al. 2008, Kale et al. 2018). Kale et al. (2018) investigated the effect of COX-2 inhibitor against atrazine-induced toxicity and observed histopathological improvement of testis in treated rats, which indicates that COX-2 plays a crucial role in atrazine-induced damages.
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