Folia Histochemica et Cytobiologica (Oct 2011)
Reproductive biology of the endangered percid Zingel asper in captivity: a histological description of the male reproductive cycle
Abstract
The endemic Rhodanian percid Zingel asper (Linnaeus, 1758), is usually found throughout the Rhônebasin, but this fish is now in sharp decline. Understanding its reproductive physiology is important so as to be ableto artificially control its reproduction with a view to re-introducing it. This study was carried out on a populationobtained by artificial fertilization and bred in external tanks. Fishes were observed from the juvenile stages throughto adulthood. Patterns of testicular development were defined from histological observations. Testes of Z. asperwere paired, elongated and fusiform dorsocaudal organs. The two lobes of each gonad joined together to forma duct that extended to the urogenital papillae. They showed a lobular structure. The testicular lobules were of theunrestricted spermatogonial type. Up to 10 months-old, most of the males were immature: their testes showed onlytype A spermatogonia. The appearance of type B spermatogonia in the lobules of a testis indicated the beginningof spermatogenesis in 10 months-old fish. Spermiogenesis occurred 24 months after the fertilization and, in 26months-old fish, the cyst opened and released spermatozoa into the lumen of lobules. The spermiation belonged toa cystic type. During the third year, histological observations pointed to the same evolution of adult gonads asduring the second year. Sexual maturity was reached in captive Z. asper after two years. The spawning occurred inMay in the breeding conditions. (Folia Histochemica et Cytobiologica 2011, Vol. 49, No. 3, 486–496)
