ENDOCRINE ASPECTS OF AGEING IN GUPPY LEBISTES RETICULATUS (PETERS) .3. TESTIS

A histological study was made of the testes of guppies ranging in age from 2 1 2 to 59 months. The testis showed a gradual loss of spermatogenic tissue and a progressive infiltration of connective tissue with age. The connective tissue sheath of the testis had thickened considerably in old fish. Atrophic and degenerate cysts were also found in senile fish, but these usually occurred side by side with apparently normal cysts. Even in extreme old age apparently normal spermatozoa were produced by the testis. Some of the changes in the senile testis of Lebistes resembled those occurring in the testes of hypophysectomized fish, and it is possible that these may result in part from a decline in the output of pituitary gonadotrophins in old age. © 1969.