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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.
Embryology, Anatomy, and Physiology of the Male Reproductive System
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Meiotic phasePrimary spermatocytes (diploid, 2n) undergo the 1st meiotic phase.Give rise to two secondary spermatocytes.Secondary spermatocyte (haploid, n) divides in the 2nd meiotic phase.Each give rise to two spermatids (haploid, n).
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.
3D bioprinting for organ and organoid models and disease modeling
Published in Expert Opinion on Drug Discovery, 2023
Amanda C. Juraski, Sonali Sharma, Sydney Sparanese, Victor A. da Silva, Julie Wong, Zachary Laksman, Ryan Flannigan, Leili Rohani, Stephanie M. Willerth
Robinson et al. report the first 3D bioprinted human adult testicular niche from a patient with non-obstructive azoospermia, serving as proof of concept for the creation of a functional bioink-based human testicular tissue [102]. Using a microfluidic 3D bioprinter fitted with a coaxial printhead, the authors propagated adult testicular cells in vitro and subsequently printed in alginate-collagen bioink without losing viability, basic phenotypes or spermatogenic potential. Microfluidic bioprinting uses microfluidic nozzles, called printheads, to build a desired 3D design of a combination of SSCs and biomaterials. The printed tubules were cultured for 12 days in supplemented media prior to assessing whether the culture could support differentiation. The authors measured gene expression levels of markers of spermatogenesis after 12 days in culture and observed substantial upregulation of meiotic and post-meiotic genes over the timeframe. They also observed meiotic spermatocytes using immunocytochemistry staining techniques. Taken together, this provides evidence for the use of 3D bioprinted human testicular tissues and establishes a baseline for future optimization of bioink components, cell patterning and bioprinting techniques.
Aluminum reproductive toxicity: a summary and interpretation of scientific reports
Published in Critical Reviews in Toxicology, 2020
The testes (singular testis) have two primary functions, to produce sperm and hormones including testosterone. The testes are composed of multiple seminiferous tubules and interstitial tissue, housed within a fibrous covering, the tunica albuginea. During embryonic development within the seminiferous germinal epithelium, Sertoli cells, which surround the developing germ cells, associate with the latter to form seminiferous tubules after birth. The seminiferous tubules are coiled masses that produce sperm cells through spermatogenesis, the maturation of germ cells to haploid spermatozoa. At birth, the seminiferous tubules contain spermatogonial stem cells. During the first round of spermatogenesis, Sertoli cells join to form tight junctions that compartmentalize the seminiferous epithelium into basal and luminal compartments. Spermatogonia, which are in the basal compartment, divide into type A spermatogonia that remain to replenish the precursor cells or type B spermatogonia. The latter, through meiosis in the luminal compartment, become (primary) spermatocytes. These divide to form secondary spermatocytes which meiotically divide to from spermatids, which are initially round. Multinucleated giant cells in the seminiferous tubules are degenerating germ cells. Spermatids become spermatozoa during late spermatogenesis.
Effects of zinc oxide nanoparticles and zinc sulfate on the testis of common carp, Cyprinus carpio
Published in Nanotoxicology, 2019
Seetharam Deepa, Raju Murugananthkumar, Yugantak Raj Gupta, Manjunatha Gowda K.S, Balasubramanian Senthilkumaran
Bouin’s fixative (15:5:1 of saturated picric acid:formaldehyde:glacial acetic acid) was freshly prepared, and testes from all the groups were fixed overnight. The samples were then dehydrated in a graded series of ethanol for 1 h each followed by xylene and finally embedded in molten paraplast (Cat. No: P3683, Sigma). Samples were sectioned into 5 μm thickness using a rotatory microtome (Wetzlar-1512, Leitz, Germany) and the slides were processed using xylene and graded ethanol series for hematoxylin and eosin staining. Histological sections of the control and treated groups were observed under a light microscope, Olympus CX41 microscope (Olympus Corporation, Tokyo, Japan) fitted with a Mp3 MicroPublisher 3.3 RTV (Q-imaging, BC, Surrey, Canada) and microphotographs were taken. Number of spermatocytes, spermatogonia, and spermatids/sperm were counted under the microscope by randomly selected 40 lumens from each sample (n = 5). Since primary and secondary spermatocytes and spermatogonia were hard to distinguish under a light microscope, they were grouped as spermatocytes and spermatogonia, respectively. Likewise, spermatids and sperm were also grouped as a single population.