FSH- and TSH-binding cells in the ovary of the developing chick embryo.

The numerical density (Nv) and location of thyroid stimulating hormone (TSH)- and follicle stimulating hormone (FSH)-binding cells in the left ovary of the chick embryo were determined on Days 6.5 through 19.5 of incubation. From Days 6.5 to 11.5, TSH- and FSH-positive cells were located in the medullary cords and there was no statistically significant difference in the Nv of these two cellular populations. However, beginning on Day 12.5 and continuing through Day 19.5, TSH and FSH were bound principally to cells of the cortical cords and there was a significant difference (P less than 0.05) between the Nv of TSH-positive and FSH-positive cells. Results are discussed in terms of a prevalent hypothesis that throughout chick embryo development the left ovary lacks specific receptors for TSH and FSH.