Mitotic activity in the rat palatal shelves during their fusion in vitro]

Rat palatal shelves explanted on gestational day 15 or 16 are cultivated with their medial-edge epithelial surface in contact. Observations of histological sections showed that, before and during the fusion of the processes, mitotic activity is always lower in the epithelium of the expected fusion zone (EFZ) than in the oral epithelium and progressively decreases during the processus of the fusion.