Lectin binding and stage-specific embryonic antigen-1 (SSEA-1) immunoreactivity were studied in the developing submandibular glands of young Syrian golden hamsters (Mesocricetus auratus) from postnatal day 1 (the day of birth) to day 28. The submandibular glands were fixed in a solution containing 6% mercuric chloride, 1% sodium acetate, and 0.1% glutaraldehyde (HgCl2-G) or 4% paraformaldehyde (4P), and embedded in paraffin. Sections from HgCl2-G fixation were stained with three lectin-peroxidase conjugates: peanut agglutinin (PNA), Ulex europeus I agglutinin (UEA I), and wheat germ agglutinin (WGA). Sections from the 4P-fixed tissues were immunostained with monoclonal antibodies against SSEA-1, sialyl SSEA-1 and fucosyl SSEA-1. On the day of birth, the terminal unit of the submandibular gland was composed of fetal type secretory cells and proacinar cells. The secretory cells were PNA, UEA I, and WGA positive. The number of secretory terminal tubule cells decreased rapidly, and lectin-positive secretory cells were replaced by adult secretory cells that did not show PNA or UEA I stainings but were weakly positive for WGA. Fetal secretory cells were positively immunostained for SSEA-1 and sialyl SSEA-1, and immature ductal cells were stained for fucosyl SSEA-1. The positive stainings disappeared with regression of the fetal epithelial cells. Hence, modulation of glycoconjugate expression in the submandibular glands, which reflects changes in secretory cells from the fetal type to adult type during postnatal development, is revealed by lectin staining and immunostaining for SSEA-1 and related antigens.