PubMed · 14042506
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H ELFTMAN. 1963. SERTOLI CELLS AND TESTIS STRUCTURE.. https://doi.org/10.1002/aja.1001130104
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Medical assistance in reproduction by its very nature requires the intrusion into the physical and psychological intimacy of two human beings, linked by love and the desire to have one or more children together. Infertility and its consequences, the intrusion of the medical third-party, can also bring disequilibrium to a couple, making it more fragile, leading to a short-term or definitive separation... but can also strengthen it. In this context, it is useful in the middle of these difficult and constraining treatments, to take the time to reflect for a while on what could arise with the employment of active listening and open conversation: the psychological consultation.
Intratubular germ cell neoplasia of unclassified type (IGCNU) is the precursor lesion of adult testicular germ cell invasive tumors. Primordial germ cells (PGCs) are recognized as the cells of origin of testicular germ cell tumors (TGCTs) because of the genetic and phenotypic characteristics analyzed. The most important risk factors responsible for abnormal development of PGCs are environmental, including the testicular dysgenetic syndromes that generate a better microenvironmentfor survival of IGCNU cells, an abnormal relationship with Sertoli cells, and an abnormal hormonal exposure at the time of testicular differentiation in utero. Furthermore, a familial TGCT susceptibility gene (TGCT1), localized at Xq27, is associated with a higher risk for bilateral tumors and possibly cryptorchidism. The normal tetraploid pattern and the consequent genomic instability of germinal cell DNA are considered sufficient per se for neoplastic transformation. The altered expression of oncogenes and suppressor genes due to nonrandom chromosomal numerical aberrations are involved in the development of IGCNU. Some of these genes are considered responsible for bilaterality, while other genes characterize the similarity between IGCNU cells and PGCs or are involved in the neoplastic transformation, histotype differentiation, and invasivity. In spite of the monomorphic seminomatous appearance of cells in IGCNU, it is becoming increasingly evident that they hide an intrinsic heterogeneity capable of committing neoplastic cells to an embryonal and pluripotent development associated or not with a seminomatous phenotype.
This is the first report on gamma-tubulin and microtubule arrays during microsporogenesis in a gymnosperm. Meiosis in Ginkgo biloba is polyplastidic, as is typical of the spermatophyte clade, and microtubule arrays are organized at various sites during meiosis and cytokinesis. In early prophase, a cluster of gamma-tubulin globules occurs in the central cytoplasm adjacent to the off-center nucleus. These globules diminish in size and spread over the surface of the nucleus. A system of microtubules focused on the gamma-tubulin forms a reticulate pattern in the cytoplasm. As the nucleus migrates to the center of the microsporocyte, gamma-tubulin becomes concentrated at several sites adjacent to the nuclear envelope. Microtubules organized at these foci of gamma-tubulin give rise to a multipolar prophase spindle. By metaphase I, the spindle has matured into a distinctly bipolar structure with pointed poles. In both first and second meiosis, gamma-tubulin becomes distributed throughout the metaphase spindles, but becomes distinctly polar again in anaphase. In telophase I, gamma-tubulin moves from polar regions to the proximal surface of chromosome groups/nuclei where interzonal microtubules are organized. No cell wall is deposited and the interzonal microtubules embrace a plate of organelles between the two nuclear cytoplasmic domains (NCDs) of the dyad. Following second meiosis, phragmoplasts that form between sister and non-sister nuclei fuse to form a complex six-sided structure that directs simultaneous cytokinesis. Gamma-tubulin becomes associated with nuclei after both meiotic divisions and is especially conspicuous in the distal hemisphere of each young microspore where an unusual encircling system of cortical microtubules develops.