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Preimplantation Genetic Testing for Structural Rearrangements
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Inmaculada Campos-Galindo, Vanessa Peinado
Most balanced carriers of chromosome rearrangements do not display an obvious phenotype: if there are no genetic material gains or losses or no truncation of a gene in the breakpoints, all of the necessary genetic information is present. However, these carriers may present with reduced fertility, repeated miscarriage, or offspring with an abnormal phenotype. In particular, heterozygotic carriers of balanced chromosome rearrangements are predisposed to produce unbalanced gametes during meiosis, through unequal meiotic segregation in translocation carriers or recombination events in inversion carriers during gametogenesis [15,16]. Thus, their condition can remain undetected until they attempt to reproduce [17].
Endocrine Therapies
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
After secretion into the bloodstream, GnRH travels via the portal blood to the pituitary gland where it acts on its own receptor known as the Gonadotropin-Releasing Hormone Receptor (GnRHR), a seven-transmembrane G-Protein-Coupled receptor (Figure 8.24). This stimulates production of the beta-isoform of Phosphoinositide Phospholipase C, which then mobilizes calcium and Protein Kinase C. This results in the activation of proteins involved in the synthesis and secretion of the two pituitary hormones, Luteinizing Hormone and Follicle-Stimulating Hormone from the anterior pituitary. These hormones induce the production of estrogen and progesterone in the ovaries in females, and testosterone in the testes in males. This, in turn, induces ovulation in females and gametogenesis in males. GnRH is the target of various regulatory processes within the hypothalamic–pituitary–gonadal axis, and is inhibited by rising levels of estrogen or testosterone in females and males, respectively (i.e., via a feedback loop).
Preimplantation Genetic Testing for Aneuploidies: Where We Are and Where We're Going
Published in Darren K. Griffin, Gary L. Harton, Preimplantation Genetic Testing, 2020
Andrea Victor, Cagri Ogur, Alan Thornhill, Darren K. Griffin
Aneuploidy results from erroneous chromosome segregation during cell division, which can occur during meiosis in gametogenesis or during mitosis in embryonic development. Both meiosis and mitosis are highly complex, coordinated processes that depend on the correct formation of an intricate network of microtubules known as the spindle, responsible for physically moving chromosomal content during cell division. Compromised formation of the spindle can prevent correct segregation of chromosomes or chromatids to daughter cells.
Effect of anti-Müllerian hormone in hypothalamic Kiss-1- and GnRH-producing cell models
Published in Gynecological Endocrinology, 2021
Aki Oride, Haruhiko Kanasaki, Tuvshintugs Tumurbaatar, Zolzaya Tumurgan, Hiroe Okada, Satoru Kyo
Mammalian reproductive function is controlled by the pituitary gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which concomitantly regulate gametogenesis and steroid synthesis. Gonadotropin synthesis and secretion in pituitary gonadotrophs are mainly under the control of gonadotropin-releasing hormone (GnRH) from the hypothalamus. Furthermore, hypothalamic kisspeptin, which is encoded by the Kiss-1 gene, governs GnRH release [1,2]. Kisspeptin-producing neurons (Kiss-1 neurons) in the hypothalamus regulate GnRH neurons which are distributed in the preoptic area and anterior hypothalamus in rodents. At present, it is generally agreed that Kiss-1 neurons in the anteroventral periventricular (AVPV) region regulate the estradiol (E2)-induced GnRH/LH surge. On the other hand, Kiss-1 neurons in the arcuate nucleus (ARC) regulate the pulsatile release of GnRH, which is under the control of E2-induced negative feedback mechanisms [2]. This concept is based on work showing that E2 upregulated Kiss-1 expression in the AVPV region but repressed that in the ARC region [3,4].
Sexual dimorphism in ultradian and 24h rhythms in plasma levels of growth hormone in Indian walking catfish, Clarias batrachus
Published in Chronobiology International, 2021
Raj Naresh Gopal, Dhanananajay Kumar, Vinay Kumar Singh, Atanu Kumar Pati, Bechan Lal
In fish, GH has been further reported to influence gametogenesis (Kajimura et al. 2004), gonadal steroidogenesis (Singh et al. 1988), vitellogenesis (Björnsson et al. 1994; Mosconi et al. 2002), and oocyte maturation (Sarang and Lal 2005). A previous report (Peng and Peter 1997) revealed that GH secretion is controlled by several metabolic and reproductive hormones. These metabolites, sex steroids, thyroid hormones, and neuroendocrine secretions interact and coordinate together to regulate GH secretion and maintain its rhythmicity (Peng and Peter 1997). In catfish, in-vivo injection of sGnRH, testosterone, and morphine caused a significant increase in plasma GH secretion. Whereas, 5-hydroxy tryptophan resulted in lowered GH levels in a dose-dependent manner (Lal and Singh 2005), indicating the role of several internal metabolic factors in regulating GH plasma production. Therefore, based on the published literature, we infer that such apparent 24 h variation in plasma GH in catfish seems to have physiological roles. For instance, GH may regulate gonadal and somatic growth and may affect reproductive processes in catfish. In female catfish, GH shows different effects on somatic growth and ovarian development. The differential effect of GH was observed to depend on the season and on the time during the 24 h of its administration (Singh and Lal 2008). Similarly, in male catfish, GH caused enhanced testicular steroidogenic and spermatogenic activities. This increase further shows dependence on photoperiod and water temperature (Gopal et al. 2014).
Therapeutic effect of adipose-derived mesenchymal stem cells on Cisplatin induced testicular damage in adult male albino rat
Published in Ultrastructural Pathology, 2019
Fatma Y. Meligy, Amal T. Abo Elgheed, Shymaa M. Alghareeb
The results obtained by Shlush et al. indicated that MSCs could differentiate into germ cells and Sertoli cells by adjusting the physiological conditions of spermatogenesis 82. Also, it could be concluded that treatment of ram BM-MSCs by BMP4, BMP8b, and TGFb1 growth factors resulted in germ cells which expressed DAZL gene(a GC-specific gene).82 The produced GCs in the TGFb1-treated culture did not express the meiotic marker, ACR, so it could be concluded that they did not enter meiosis. According to some other researchers, meiosis has been a great barrier for the achievement of complete gametogenesis from in vitro-derived GCs9,76; however, the use of Retinoic acid for induction of differentiation plays an important role in the observation of the haploid status of the differentiated cells.83