FSH- and LH-cells originate as separate cell populations and at different embryonic stages in the chicken embryo.

The histological distribution of gonadotrophs containing either LH or FSH, but not both gonadotropins, has been demonstrated before in the juvenile and adult chicken throughout the caudal and cephalic anterior pituitary lobes. In the present investigation, the distribution of FSH- and/or LH-containing gonadotrophs was further investigated in the chicken embryo by use of the same homologous antibodies as used in our earlier study. Fluorescent dual-labeling immunohistochemistry revealed that during embryogenesis LH and FSH reside exclusively in separate gonadotrophs, as has been described before in the post hatch bird.