The spatial distribution and temporal expression of alpha-D-mannosyl(glucosyl)-, N-acetyl-D-glucosaminyl- and beta-D-galactosyl residues as detected by peroxidase-conjugated lectins correlated with early odontogenic events in six principal developmental stages (fetal days 13.5, 14, 15, 17, 18.5 and 19.5). The odontogenic epithelium of 13.5- and 14-day-old fetuses was characterized by strong concanavalin A (Con A) binding and between days 17 and 19.5, the stellate reticulum displayed strong peanut agglutinin (PNA) binding. Between 15 and 19.5, differentiation of dental ectomesenchyme was characterized by a rhythmic expression of terminal galactosyl residues shown by PNA-binding. At the developing dental basement membrane, there were various carbohydrate-specific regions. At days 13.5 and 14, the odontogenic basement membrane was specific for N-acetyl-D-glucosamines detected by wheat-germ agglutinin (WGA). The results suggest that the carbohydrates present at the inner dental basement membrane at days 17 to 19.5 may be involved in cell-matrix interactions during cytodifferentiation.