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Retinoic acid signaling in spermatogenesis and male (in)fertility
Published in Rajender Singh, Molecular Signaling in Spermatogenesis and Male Infertility, 2019
Dario Santos, Rita Payan-Carreira
Spermatogenesis is a complex, highly tuned and orderly process occurring in the seminiferous tubules in male testes. During spermatogenesis, diploid germ cells timely engage in the process of multiplication and differentiation that ends with the release of spermatozoa (a haploid cell) into the lumen of the seminiferous tubules (1). One round of spermatogenesis encompasses three stages: (a) the mitotic proliferation of spermatogonia (SPG), often named as spermatocytogenesis; (b) the reductional meiosis by spermatocytes (SPCs); and (c) the differentiation of spermatids (SPD), an unique maturational process during which an initial round cell transforms into a highly specialized flagellated cell with tightly condensed chromatin and an acrosome—the spermatozoon (2,3). The sequential progress of these three stages is tightly regulated in both time and space, under the orchestrated control of Sertoli cells, Leydig cells and the germ cells themselves (2), fostering a stage-related environment to the developing germ cells.
Saccharomyces cerevisiae
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Brunella Posteraro, Gianluigi Quaranta, Patrizia Posteraro, Maurizio Sanguinetti
As mating occurs only between a and α cells, the two types of haploid, describing mating behavior, are often called mating types.18 All three cell types can divide mitotically under favorable environmental conditions—S. cerevisiae is able to grow on a modest array of fermentable and nonfermentable carbon sources (mostly six-carbon sugars). However, budding yeasts and other predominantly diploid species—many other yeast species, for example, K. lactis, S. pombe, are primarily haploid—do not undergo, after germination of the meiotic spore, haploid phase of cell divisions (or only a very short one), and as soon as a partner (i.e., haploid cell of opposite mating type) is found will fuse to form a diploid cell. Haploid cells secrete pheromones to signal mating, and respond by growing a mating projection toward a potential mate. Following contact of two partner cells and their fusion, diploids will continue asexual growth and will upon induction by nutrient-limiting environmental conditions—specifically starvation of nitrogen in the presence of a nonfermentable carbon source—complete the sexual cycle that results in the production of meiotic offspring.16
The rise of genomics and personalized medicine
Published in Priya Hays, Advancing Healthcare Through Personalized Medicine, 2017
How is the human genome, the complete set of genetic information, organized? A human inherits 3 billion base pairs from each parent. The sperm and egg contain a haploid set of chromosomes; a haploid cell contains 3 billion base pairs (or 6 billion bases), or 23 chromosomes. A diploid cell results containing 6 billion base pairs (twice the DNA content of a haploid cell) and 23 pairs (or 46) chromosomes when sperm and egg unite. There are 23 pairs of chromosomes, including 22 autosomes and sex chromosomes in each diploid cell. The sex chromosomes consist of the X and Y chromosomes, with females having a pair of X chromosomes and males having one X chromosome and one Y chromosome. Chromosomes range in size from 42 million base pairs (chr22) to 240 million base pairs (chr1).
Cigarette smoking and its toxicological overview on human male fertility—a prospective review
Published in Toxin Reviews, 2021
R. Parameswari, T. B. Sridharan
Semen is a male reproductive fluid, which is composed of spermatozoan and seminal fluid/plasma. Spermatozoan, a haploid cell, flagellate, swims in this fluid, capable of fertilizing ova, and is ejaculated from a male reproductive system and involved in human fertilization. The seminal fluid is secreted by various secreting glands that are present in a male reproductive system, such as urethral glands (5%), vas deferens (10%), seminal vesicle (40%), prostate gland (20%), seminiferous tubules of testicle (5–10%) and epididymis (5%) (Owen and Katz 2005). The quality of the semen is determined by the following parameters as per World Health Organization (WHO) (2010) as follows:
Per- and polyfluoroalkyl substances impact human spermatogenesis in a stem-cell-derived model
Published in Systems Biology in Reproductive Medicine, 2018
Alyse N. Steves, Adam Turry, Brittany Gill, Danielle Clarkson-Townsend, Joshua M. Bradner, Ian Bachli, W. Michael Caudle, Gary W. Miller, Anthony W. S. Chan, Charles A. Easley
Haploid cell production and cell cycle progression were assessed by generating cell cycle plots revealing haploid cell, G0/G1, S phase, and G2 peaks using the Muse® Cell Cycle Assay Kit (MilliporeSigma, Billerica, MA) by staining fixed cells with propidium iodide as per manufacturer’s instructions to prepare samples for flow cytometry. Samples were run on the Muse® benchtop flow cytometer (MilliporeSigma, Billerica, MA). For each flow cytometry-based experiment, 5,000 events were analyzed for three replications (n = 3) per chemical concentration and DMSO-only control. Haploid peaks were analyzed using guavaSoft™ 3.1.1 (MilliporeSigma, Billerica, MA).