The influence of retinoic acid on growth and morphology of rat exorbital lacrimal gland acinar cells in culture

The lacrimal gland transports and metabolizes retinoids and may require vitamin A for normal function. To study effects of retinoic acid on morphology and growth of the lacrimal gland, rat lacrimal acinar cells were cultured in medium with serum or in serum-free medium in the presence or absence of retinoic acid. In the presence of serum, the acinar cells have a somewhat fibroblastic morphology and form confluent layers. Addition of retinoic acid to these cultures causes formation of tubule-like structures. Retinoic acid inhibits the growth of lacrimal cells in medium with serum and the cells do not reach confluence; however, the labeling of the cells with bromodeoxyuridine is not affected by retinoic acid. In serum-free medium the growth of acinar cells is reduced, but their morphology is epithelial and structures resembling secretory domes are present. Retinoic acid causes a further reduction in growth, domes are absent, and cell spreading and enlargement occurs. The effects of retinoic acid on growth and morphology of lacrimal acinar cells in culture are complex and the relevance of these observations to lacrimal function in vivo is unclear; the study demonstrates, however, that these cells are responsive to retinoic acid.