A brief survey of the modifications in sensory-secretory organs of the neonatal rat tongue.

Recent data obtained on rats suggest that in the days immediately following birth several events take place in the circumvallate papillae of the oral cavity. A phylogenetically primitive system of solitary chemosensory cells develops and is rapidly replaced by taste buds. The lipase-secreting von Ebner gland, which is associated with taste organs, begins to develop by forming short tubules. The intrinsic nervous system of the gustatory organs rapidly completes its maturation showing fast proliferation of fibers and immunocytochemical maturation. Intraepithelial lipid accumulation is visible in the non-receptorial mucosa of the tongue, showing aspects which suggest an active lipid secretion. These data demonstrate that in the rat the structure of the sensory-secretory organs of the newborn's tongue shows a typical conformation with respect to the adult and rapidly changes its organization in the first week after the birth. At the present level of knowledge, it is difficult to link the anatomical structures to peculiar functional roles but the rather simple organization of the neonatal gustatory epithelium could be in relation to the dietary regimen. The data obtained in laboratory animals underline the necessity of studies on human newborns to update the anatomical knowledge of the oral chemoceptive system.