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During adolescence, androgens are responsible for the development of secondary sexual characteristics, pubertal growth, and the anabolic effects on bone and muscle mass. Testosterone is the most abundant testicular androgen, but some effects are mediated by its conversion to the more potent androgen dihydrotestosterone (DHT) or to estradiol. Androgen deficiency, requiring replacement therapy, may occur due to a primary testicular failure or secondary to a hypothalamic-pituitary disorder. A very frequent condition characterized by a late activation of the gonadal axis that may also need androgen treatment is constitutional delay of puberty. Of the several testosterone or DHT formulations commercially available, very few are employed, and none is marketed for its use in adolescents. The most frequently used androgen therapy is based on the intramuscular administration of testosterone enanthate or cypionate every 3 to 4 weeks, with initially low doses. These are progressively increased during several months or years, in order to mimic the physiology of puberty, until adult doses are attained. Scarce experience exists with oral or transdermal formulations. Preparations containing DHT, which are not widely available, are preferred in specific conditions. Oxandrolone, a non-aromatizable drug with higher anabolic than androgenic effects, has been used in adolescents with preserved testosterone production, like Klinefelter syndrome, with positive effects on cardiometabolic health and visual, motor, and psychosocial functions. The usual protocols applied for androgen therapy in boys and adolescents are discussed.

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OBJECTIVE: To study the outcomes of testicular sperm extraction (TESE) among men with pure Sertoli cell-only histology identified during diagnostic testicular biopsy. METHODS: This retrospective cohort study involved 1680 cases of patients with nonobstructive azoospermia (NOA) diagnosed with pure Sertoli cell-only histology who underwent testicular biopsy with TESE in a reference center in Brazil by a single surgeon. Sperm retrieval rates (SSR) were the main outcome measure. RESULTS: Overall, 14.83% of patients with Sertoli cell-only had sperm retrieved with TESE in quantity that allowed the performance of ICSI. No differences were observed in SSR based on testis volume (<15 mL vs. <15 mL) or serum FSH level. CONCLUSIONS: Patients with Sertoli cell-only histology can be counseled that they have some likelihood of sperm retrieval with TESE. Based on the findings, patients to be submitted to testicular biopsy for histologic analysis may be concomitantly prepared for ICSI with TESE in case sperm is available.

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Últimamente ha cobrado gran interés en la comunidad médica y científica, el avance experimentado por la medicina regenerativa, la ingeniería de tejidos y el uso de terapias celulares en base a células autólogas maduras, como también el uso de células madre. Desde que se levantó en Estados Unidos, la prohibición de investigar con células madre embrionarias, se ha producido un aumento de las investigaciones en este campo. El interés por estas investigaciones, se ha traspasadoa la comunidad no científica, que se encuentra expectante frente al progreso que se logre, con las terapias derivadas de tales estudios. En medicina reproductiva, existe la esperanza de poder producir células germinales tanto femeninas como masculinas (ovocitos o sus precursores y espermatozoides o sus precursores), a partir de células madre, para tratar pacientes con falla gonadal (ovárica o testicular), que hasta ahora resuelven su problema de infertilidad, mediante el uso de gametos donados, prevaleciendo la falla endocrina, que se resuelve con la administración de reemplazo hormonal. Las células madre son células indiferenciadas, toti potenciales que bajo ciertas condiciones, pueden diferenciarse a células especializadas. La medicina regenerativa se vale de la ingeniería de tejidos y las terapias celulares con células autólogasmaduras y también con células madre. Este artículo es una revisión bibliográfica sobre las últimas investigaciones en el campo de la medicina regenerativa y el uso de células madre en medicina reproductiva. Se describen los diferentes tipos de células madre y los tejidos que se ha logrado reproducir in vitro hasta ahora, como también algunos estudios en animales y su aplicación en humanos.

In the last years, the scientific and non-scientific community have been motivated by the great advances in the field of regenerative medicine, tissue engineering and cell therapies (using either mature autologous cells or stem cells). Since the beginning of 2009, once the prohibition of research in embryonic stem cells was abolished, there has been an increase in research in this field. There is great expectation, specially in the field of reproductive medicine and infertility where there exists the hope to produce germinal cells (oocytes and sperms) to treat couples with gonadal failure (ovarian o testicular). In these patients, gamete donation and permanent hormonal replacement therapy have resolved their fertility and/or endocrine problems. Regenerative medicine uses tissue engineering, and cell therapies to repair the function of a damaged organ. Stem cells are undifferentiated, toti potentially cells, that under certain conditions or milieu may differentiate to specialized cells. This article is a bibliographic review of the most recent investigations in the field of regenerative medicine and stem cell therapies, using animal models and their application to humans.

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