Summary. Several Introduction.

In the upper third of the vagina of the immature rat, the innermost epithelial layer was formed by secretory cells in which mucus appeared at day 14 of postnatal life and increased thereafter until day 30. Histochemical examination showed that the mucus was a glycoprotein material rich in sialic acid and containing some sulfate. The luminal glycocalyx of the mucous cells, barely recognizable at day 10 with the periodic acid-Schiff procedure (PAS), was distinctly shown with Alcian blue and increased with age. The glycocalyx contained a glycoprotein rich in sulfate with little sialic acid. Castration at day 25 reduced the mucous content as well as the glycocalyx components. Castrated 10-day-old rats which received estrogens showed keratinization but no mucif ication at day 16, whereas estrogens plus progesterone induced mucification and glycocalyx development. 10-day-old rats injected with pregnant mare serum gonadotropin hormone (PMSG) revealed mucification and glycocalyx development at day 16, whereas PMSG plus human chorionic gonadotropin hormone (HCG) inhibited mucification but notably increased the glycocalyx components. HCG alone had no effect on mucification or on the glycocalyx. Our observations indicated that certain constituents of the glycocalyx of the mucous cells of the vagina of the immature rat are synthesized before these cells become capable of producing the glycoprotein(s) of the intracellular mucous material.