Prenatal Morphogenesis of Testis in Sheep (Ovis aries)

Abstract

The present study was undertaken to elucidate the developmental changes in the testis. The study was conducted on 38 embryos and foetuses of sheep collected from local abattoirs from 37 to 122 days (0.7 to 41 cm CRL) were collected and divided into three age groups basing on gestation periods. In group I, at 42 days of gestation, testes were located in between the metanephric kidneys medially and mesonephros laterally in the lumbar region and scrotal bud was first observed in the inguinal region. At 59 days of gestation, the testes were located at caudal pole of kidney. At 94 days of age, the descent of testes into the scrotum was completed. At 122 days of gestation, testes were located in the scrotal sac. At 44 days of gestation, testes were oblong in shape but testes were changed to oval at 46 days of foetal life later became elongated at 60 days of gestation. The genital ridge was first observed between the mesonephoros and primitive gut in 37 day old sheep foetus. At 39 days of gestation, the gonadal anlages protruded into the coelomic cavity as paired oval-shaped structures on either side of the dorsal mesentery of the hindgut medial to the mesonephros.