Development of urogenital system in the Spix cavy: A model for studies on sexual differentiation.

This study documented, for the first time, the morphological patterns of differentiation of male and female genital organs of Spix cavy (Galea spixii) using histological and ultrastructural analyses, with immuno-localization of steroidogenic enzymes, cytochromes P450 aromatase (P450arom) and 17α-hydroxylase/17, 20-lyase (P450c17), involved in the synthesis of estrogens and androgens respectively throughout fetal sexual development. Undifferentiated gonads of Spix cavy develop into ovaries in females after 25 days of gestation (DG), exhibiting P450arom immunoreactivity. After 25 DG, paramesonephric ducts develop and form oviducts, uterine horns and cranial portion of the vagina. The caudal portion of the vagina originates from the urogenital sinus, and a vaginal closure membrane is present at the end of gestation. Partial channeling of the urethra into the clitoris occurs after 40 DG, but complete channeling never occurs. A preputial meatus emerges near the tip of organ. In males, undifferentiated gonads develop into testes at 25 DG and develop immunoreactivity for P450c17, which is required for androgens synthesis and likely maintenance of mesonephric ducts. Mesonephric ducts develop subsequently, forming the epididymis and ductus deferens. The pelvic urethra develops after 25 DG with channeling into the penis occurring around 30 DG. This is the first morphological study describing the process of sexual differentiation during gestation in a hystricomorph rodent and one of the most comprehensive analyses conducted in any mammal. Male genital organ development follows the general pattern described in other domestic mammals, but does not include formation of the baculum as occurs in mice and rats. In females, clitoral development includes partial canalization by the urethra and development of a preputial meatus. Further studies are required to clarify the mechanisms involved in the differentiative processes described.

Identification of fetal sex ln uterus of goats and ewes by ultrasonography / Identificação do sexo de fetos em úteros de cabras e ovelhas utilizando a ultra-sonografia

ln this work the objective was to identify the fetal sex in pregnant uterus, between 5 and 10 weeks of gestation, of goats and ewes obtained in slaughterhouses. The sex was defined taking into consideration the localization of the genital tubercle (GT) and visualization of external genitalia. The uterus of goats (n =108) and ewes (n = 64) were examined after immersion in a water containing recipient, with 6.0 and 8.0 MHz linear transducer. In single pregnancies, the correct fetal determination was 85.7% (48/56) in goats and 94.7% (36/38) in ewes and in twin pregnancies it was 76.9% (40/52) in goats and 84.6% (22/26) in ewes. There were no mistakes in fetal quantification and the accuracy of all fetuses scanned was of 81.5% (88/108) in goats and 90.6% (58/64) in ewes, not being observed difference (P > 0.05) between species, by analysis of standard errors of the difference between proportions. The results allow to conclude that the ultrasonography is efficient to previously identify the fetal sex in small ruminants and that the experience of the operator is important to minimize and even eliminate the failures in diagnose.

Neste trabalho, o objetivo foi de identificar o sexo fetal em úteros, entre 5 e 10 semanas de gestação, de caprinos e ovinos obtidos em matadouro. O sexo foi definido levando-se em consideração a localização do tubérculo genital (TG) e a visualização da genitália externa. Os úteros das cabras (n =108) e ovelhas (n =64) foram examinados após imersão em recipiente contendo água, com transdutor linear de 6.0 e 8.0 MHz. Nas gestações simples, o acerto na identificação do sexo fetal foi 85,7% (48/56) nos caprinos e de 94,7% (36/38) nos ovinos e nas gestações duplas foi de 76,9% (40/52) nos caprinos e de 84,6% (22/26) nos ovinos. Não ocorreram erros na determinação do número de fetos e de todos os fetos examinados. A acurácia da sexagem foi de 81,5% (88/108) nos caprinos e de 90,6% (58/64) nos ovinos, não sendo observada diferença (P > 0,05) entre espécies, pelo cálculo do erro padrão da diferença entre as proporções. Os resultados permitem concluir que a ultra-sonografia é eficiente para identificar precocemente o sexo fetal nos pequenos ruminantes e que a experiência do operador é fundamental para minimizar e até mesmo eliminar a emissão de diagnósticos equivocados.

Identification of fetal sex ln uterus of goats and ewes by ultrasonography / Identificação do sexo de fetos em úteros de cabras e ovelhas utilizando a ultra-sonografia

ln this work the objective was to identify the fetal sex in pregnant uterus, between 5 and 10 weeks of gestation, of goats and ewes obtained in slaughterhouses. The sex was defined taking into consideration the localization of the genital tubercle (GT) and visualization of external genitalia. The uterus of goats (n =108) and ewes (n = 64) were examined after immersion in a water containing recipient, with 6.0 and 8.0 MHz linear transducer. In single pregnancies, the correct fetal determination was 85.7% (48/56) in goats and 94.7% (36/38) in ewes and in twin pregnancies it was 76.9% (40/52) in goats and 84.6% (22/26) in ewes. There were no mistakes in fetal quantification and the accuracy of all fetuses scanned was of 81.5% (88/108) in goats and 90.6% (58/64) in ewes, not being observed difference (P > 0.05) between species, by analysis of standard errors of the difference between proportions. The results allow to conclude that the ultrasonography is efficient to previously identify the fetal sex in small ruminants and that the experience of the operator is important to minimize and even eliminate the failures in diagnose.

Neste trabalho, o objetivo foi de identificar o sexo fetal em úteros, entre 5 e 10 semanas de gestação, de caprinos e ovinos obtidos em matadouro. O sexo foi definido levando-se em consideração a localização do tubérculo genital (TG) e a visualização da genitália externa. Os úteros das cabras (n =108) e ovelhas (n =64) foram examinados após imersão em recipiente contendo água, com transdutor linear de 6.0 e 8.0 MHz. Nas gestações simples, o acerto na identificação do sexo fetal foi 85,7% (48/56) nos caprinos e de 94,7% (36/38) nos ovinos e nas gestações duplas foi de 76,9% (40/52) nos caprinos e de 84,6% (22/26) nos ovinos. Não ocorreram erros na determinação do número de fetos e de todos os fetos examinados. A acurácia da sexagem foi de 81,5% (88/108) nos caprinos e de 90,6% (58/64) nos ovinos, não sendo observada diferença (P > 0,05) entre espécies, pelo cálculo do erro padrão da diferença entre as proporções. Os resultados permitem concluir que a ultra-sonografia é eficiente para identificar precocemente o sexo fetal nos pequenos ruminantes e que a experiência do operador é fundamental para minimizar e até mesmo eliminar a emissão de diagnósticos equivocados.