In this investigation, the observations were made on the secretion materials in the surface epithelium of the quail uterus, with reference to their histochemical properties and their quantitative changes related to the egg formation. These results are summarized as follows:
1. The mucous surface epithelium in the uterus of the quail consisted of the apical ciliated cells and the basal mucous cells as described in the domestic fowl by RICHARDSON (1935) and JOHNSTON et al. (1963).
2. Three types of secretion materials were found in the epithelium; the pigment granules (porphyrin) and the PAS-positive granules in the apical cells and the basophilic mucin granules in the basal cells.
3. Histochemically, the pigment granules were presented as pigment protein, the PAS-positive granules as neutral mucopolysaccharide-protein complex and the mucin granules as acid mucopolysaccharide-protein complex.
4. The PAS-positive granules and the pigment granules showed parallel appearances in their quantitative changes in the cells; they were maximum in the stage of the shell formation, then released into the uterine lumen to form their mingled structures, which were considered as the cuticular material.
5. The mucin granules in the basal cells were maximum in the stage of shell-membrane formation, and then released into the lumen, prior to the pigment and the PAS-positive granules. They were considered as related to the formation of the organic matrix of the shell.