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Sperm Banking
Published in Botros Rizk, Ashok Agarwal, Edmund S. Sabanegh, Male Infertility in Reproductive Medicine, 2019
Rakesh Sharma, Alyssa M. Giroski, Ashok Agarwal
Experimental options are available for fertility preservation in prepubertal boys as spermatogenesis has not resulted in the formation of spermatids or spermatozoa. Testicular tissue and germ cell preservation in young patients with cancer is an experimental option. Spermatogonial stem-cell transplantation is a novel method where there is ongoing research for fertility preservation in both prepubertal and adult males. Spermatogonial germ cells are present in prepubertal testicular tissue and can be isolated and successfully cryopreserved [49]. These stem cells have the potential to be transplanted autologously into the testis where they are expected to recolonize the seminiferous tubules and initiate spermatogenesis. Autotransplantation is not recommended in cases where the potential for occult metastasis is high. In such situations, transplantation of human spermatogonial cells into animals can be performed (xeno-transplantation) under experimental conditions [50,51]. However, the risk of introducing animal infectious retroviruses into the human germ line is a possibility when these cells are used for conception [52]. Ischemic damage to transplanted testicular tissue, in vitro enrichment of stem-cell spermatogonia, and noninvasive transfer of germ cell suspension into the rete testis are some other challenges associated with this technology.
The mitotic phase of spermatogenesis
Published in C. Yan Cheng, Spermatogenesis, 2018
In healthy men, millions of sperm are produced daily in the testis through a process known as spermatogenesis, owing to the tremendous replenishing power of spermatogonia, a heterogeneous population consisting of both spermatogonial stem cells (SSCs) and committed progenitors.1 The spermatogonia need to undergo three phases—the mitotic phase, the meiotic phase, and the postmeiotic differentiation phase—to give rise to spermatozoa. In the mitotic phase, spermatogonia undergo a series of mitosis to expand the number of daughter cells. These daughter cells have two fates: (1) self-renewal to maintain the stem cell pool, and (2) committed to differentiation and give rise to primary spermatocytes that enter the meiotic phase. Since the primary spermatocytes will only undergo two rounds of meiotic division whereas the spermatids undergo differentiation without division, the mitotic phase is considered the foundation that provides a steady supply of a large number of committed progenies while maintaining the stem cell pool to sustain spermatogenesis. Perturbation of the homeostasis between spermatogonial self-renewal and differentiation has detrimental effects on spermatogenesis.
Processing and cryopreservation of testicular sperm
Published in David K. Gardner, Ariel Weissman, Colin M. Howles, Zeev Shoham, Textbook of Assisted Reproductive Techniques, 2017
Amin S. Herati, Mark C. Lindgren, Samuel J. Ohlander, Larry I. Lipshultz
A potential strategy for using the immature cryopreserved testicular tissue involves spermatogonial stem cells. Spermatogonial stem cells are capable of self-renewal and differentiation into mature spermatozoa for the sole purpose of transmission of the genome to the next generation. Germ cell transplantation was developed in rodent models and successfully performed by Brinster and Avarbock in 1994 (60). Microinjection of spermatogonial stem cell suspensions into the seminiferous tubules of infertile mice stimulated spermatogenesis. Cryopreservation of spermatogonial stem cells before the start of any cancer therapy followed by autologous intratesticular transplantation of these cells after cure offers potential for preserving fertility (60,61). Offering human spermatogonial stem cell auto-transplantation as an option for fertility preservation to patients becomes more tangible every day. There are institutions that recognize the realistic potential of this being a valid option for patients in the near future (61), so much so that they have begun to offer cryopreservation of testicular tissue in the hope that within the next 10 years science will have solved all of the intricacies of stem cell transfer to revolutionize the ability to preserve fertility.
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
There exists a need for an in vitro biomimetic testicular model to evaluate human testicular function, and to perform medication, drug and toxicology screens. The spermatogenic niche consists of somatic cells and supports spermatogenesis and testosterone production. These somatic cells consist of Sertoli cells, myoid cells, Leydig cells, endothelial cells, and macrophages. These cells help coordinate a complex, highly regulated sequence of processes to support the differentiation of spermatogonial stem cells (SSC) to haploid spermatids, referred to as spermatogenesis; as well as the morphologic maturation of round spermatids to elongated spermatozoa, termed spermiogenesis. The somatic cells of the testicular microenvironment govern the temporal and spatial regulation of these events through direct contact, juxtracrine and paracrine signaling.
Differentiation of neonate mouse spermatogonial stem cells on three-dimensional agar/polyvinyl alcohol nanofiber scaffold
Published in Systems Biology in Reproductive Medicine, 2020
Marzieh Ziloochi Kashani, Zohreh Bagher, Hamid Reza Asgari, Mohammad Najafi, Morteza Koruji, Fereshteh Mehraein
Since spermatogenesis begins shortly after birth in rodents, the testicular cells of 3–6-day-old mice were used in this research work. During this period, a population of undifferentiated spermatogonial stem cells arises from a subset of gonocytes which are located within the center of seminiferous tubules (Drumond et al. 2011). These undifferentiated cells are called type Asingle spermatogonia and have classically been considered as the SSC population (Ehmcke et al. 2006). Mitotic division of Asingle produces committed progenitor spermatogonia (i.e., Apaired and Aaligned) which, along with Asingle cells, are collectively regarded as undifferentiated A-spermatogonia according to morphological characteristics (Clermont and Bustos-Obregon 1968; Fayomi and Orwig 2018). Further mitotic divisions of undifferentiated A-spermatogonia generate a series of differentiating spermatogonia, including A1, A2, A3, A4, intermediate, and B spermatogonia. Eventually, type B spermatogonia differentiate into primary spermatocytes that will undergo two meiotic divisions to generate round spermatids. Morphological differentiation (spermiogenesis) of these haploid cells leads to the development of mature sperms.
Repeated administrations of Mn3O4 nanoparticles cause testis damage and fertility decrease through PPAR-signaling pathway
Published in Nanotoxicology, 2020
Xiao Zhang, Zongkai Yue, Haijun Zhang, Lu Liu, Xiaomeng Zhou
It is well known that spermatozoa are produced from spermatogonial stem cells by a series of process involving mitosis, meiosis and cellular differentiation, and spermatogenesis is essential for sexual reproduction (Oliva and Castillo 2011). Meanwhile, spermatogenesis process is subjected to the neuroendocrine hypothalamic-pituitary-gonadal (HPG) axis (Huleihel and Lunenfeld 2004). In addition, hormones secreted by hypothalamus are transported to the pituitary gland via the blood and then induce the production and secretion of gonadotropins which in turn are transported to testes by the blood (Kong et al. 2014). LH stimulates the Leydig cells in the testes to synthesize and secrete the testosterone (Li et al. 2013). FSH and T stimulate Sertoli cells to produce androgen binding protein and improve the formation of the BTB, meanwhile, FSH and T could support and nourish the sperm cells during their maturation (Sofikitis et al. 2008). In this study, the serum T, FSH, and LH levels in serum of rats were determined to investigate the effect of Mn3O4-NPs on sex hormones. The serum T and FSH levels were significantly decreased in Mn3O4-NPs-120 d compared with those in the Mn3O4-NPs-0 d and Mn3O4-NPs-60 d, indicating that the serum T and FSH were suppressed in a time-dependent manner after administrated with Mn3O4-NPs. All results suggest that Mn3O4-NPs can disturb the normal HPG axis function which correlated with the malfunction in spermatogenesis and male infertility.