Estrogen, progesterone and testosterone receptors in human fetal cartilaginous tissue: immunohistochemical studies.

Computerized image analysis was used to study the distribution in cartilage of receptors to estrogen, progesterone, and testosterone during human fetal development. We have examined three histologically distinct cell groups (hypertrophic, proliferating, and reserve zones) in long bones, vertebrae, and trachea from 19 fetuses. Comparisons were made across gender and gestational age. Contrasting with controls, we examined the density of receptors, the size of the nuclear area in which the receptors were detected, the number of hormone receptor-bearing cells, and the total receptor quantity per sample. We found that estrogen, progesterone, and testosterone receptors were detected in the nuclei of all cell types, in both female and male embryonic cartilaginous tissue. Gender differences were small and inconsistent. Changes associated with gestational age depicted a pattern of hormone receptor manifestation, shifting from the immature cell types to more differentiated cells. This was evident from the receptor densities and from the cellular area in which receptors were sighted. These dynamics are accompanied by a general increase in receptor content per sample, brought about by the concomitant increase in receptor containing area size and cell number. The increase in receptor levels seems to reflect the maturation and growth of the fetal skeleton.