La importancia del sexo fetal en la ecografía morfológica: genitales ambiguos y disgenesia gonadal mixta / The importance of fetal sex in morphological ultrasound: ambiguous genitalia and mixed gonadal dysgenesis

La identificación del sexo fetal forma parte de la ecografía de segundo trimestre. En ocasiones se presentan anomalías genitales que no permiten definirlo adecuadamente, lo que se conoce como genitales ambiguos. La importancia de los mismos se debe a su asociación con desórdenes del desarrollo sexual, patologías más complejas y graves. En la mayoría de casos el diagnóstico y el manejo es postnatal, estando bien establecido. El diagnóstico prenatal, en cambio, es poco frecuente, limitado y menos conocido. Presentamos el caso de una gestante de 20 años con el hallazgo de genitales ambiguos en semana 29 y posteriormente se diagnosticó de disgenesia gonadal mixta (AU)

Fetal sex identification is a well-established part of the second trimester ultrasound. Sometimes there are genital abnormalities that prevent proper identification, called ambiguous genitalia. Its importance is based on its association with development sex disorders, a far more severe and complex diseases. In most of the cases, diagnosis and management are postnatal and well systematized. Prenatal diagnosis, however, is less frequent and more limited. We present the case of a 20 year old pregnant with a finding of ambiguous genitalia at 29 week and a diagnosis of mixed gonadal dysgenesis (AU)

Production of androgenetic diploid loach by cold-shock of eggs fertilized with diploid sperm.

Diploid androgenotes were produced without egg irradiation in the loach, Misgurnus anguillicaudatus. Eggs of wild-type diploid females were fertilized with diploid sperm of a neo-tetraploid male and then cold-shock treated at 3 °C (range, ±0.5 °C) for 30 minutes just after fertilization to eliminate the female nucleus. After hatching, ploidy status of the hatched larvae was analyzed by flow cytometry, which revealed putative diploid androgenotes as well as larvae possessing other ploidies. Five independent microsatellite DNA markers were genotyped to confirm all-male inheritance of the resultant diploid larvae. The mean ± SD yield rate of diploid androgenetic larvae to total eggs used was 12.29 ± 3.25% in the cold-shock group and 22.23 ± 13.42% in the UV-irradiated group (P > 0.05). No diploid androgenetic larvae were detected in the intact control group. To our knowledge, this is the first report demonstrating successful induction of diploid androgenotes without egg irradiation in fish.

Estrogen rescues masculinization of genetically female medaka by exposure to cortisol or high temperature.

Medaka (Oryzias latipes) is a teleost fish with an XX/XY sex determination system. Recently, it was reported that XX medaka can be sex-reversed into phenotypic males by exposure to high water temperature (HT) during gonadal sex differentiation, possibly by elevation of cortisol, the major glucocorticoid produced by the interrenal cells in teleosts. Yet, it remains unclear how the elevation of cortisol levels by HT causes female-to-male sex reversal. This paper reports that exposure to cortisol or HT after hatching inhibited both the proliferation of female-type germ cells and the expression of ovarian-type aromatase (cyp19a1), which encodes a steroidogenic enzyme responsible for the conversion of androgens to estrogens, and induced the expression of gonadal soma-derived growth factor (gsdf) in XX gonads during gonadal sex differentiation. In contrast, exposure to either cortisol or HT in combination with 17ß-estradiol (E2) did not produce these effects. Moreover, E2 completely rescued cortisol- and HT-induced masculinization of XX medaka. These results strongly suggest that cortisol and HT cause female-to-male sex reversal in medaka by suppression of cyp19a1 expression, with a resultant inhibition of estrogen biosynthesis. This mechanism may be common among animals with temperature-dependent sex determination.