"In vitro" assay of rat spermatogonial chalone in prepuberal seminiferous tubules.

The spermatogonial chalone activity is analyzed in correlation to the germinal cell population present in the seminiferous tubules of prepuberal rats. The assay is done in an "in vitro" system and aims at identifying the cell type that produces the chalone. It was found that the spermatogonial chalone is produced by the germinal cells, its production increases with the age of the animals and attains its maximum in 40 days old rats. There is a direct relationship between the amount of chalone produced and the number of spermatocytes present in the seminiferous tubules of prepuberal rats. The response of the germ cells to the chalone is maximal by 25 days of age. The apparent decrease of response in 40 days old rats may be related to the establishment of a complete germ cell line.