Appearances and chronological changes of mummichog Fundulus heteroclitus FSH cells and LH cells during ontogeny, sexual differentiation, and gonadal development.

To examine relationships between gonadal stages and the initial appearance and subsequent development of gonadotrophs, hatched larvae of the mummichog Fundulus heteroclitus were reared until first maturity under suitable conditions for maturation (20 degrees C-16L). Evident FSH cells generally appeared 1-2 weeks after hatching (wah), around or slightly before the morphological sex differentiation which occurred at 2 wah. During this period, 3beta-hydroxysteroid dehydrogenase positive cells also appeared in the gonads.