Two or three weeks after the rupture of the buccopharyngeal membrane, when the embryo is about 6 weeks old, certain areas of basal cells of the oral ectoderm proliferate more rapidly than do the adjacent areas. This leads to the formation of the primary epithelial band which is a band of epithelium that has invaded the underlying ectomesenchyme along each of the horseshoe-shaped future dental arches. About 7th week the primary epithelial band divides into an inner (lingual) process called the dental lamina.

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Dental lamina is the first evidence of tooth development.
Total activity of dental lamina extends over a period of at least 5 years