Lipoprotein secretion during the formation of the axial skeleton in Leptogorgia virgulata (Cnidaria: Gorgonacea).

A lipoprotein-secreting role is associated with a population of skeletogenic cells in the gorgonian coral, Leptogorgia virgulata (Lam.). Electron-microscopical and cytochemical studies show that these cells, the medullocytes, occur almost exclusively at the growing skeletal tip and are morphologically and functionally distinct from those cells that thicken the skeletal cortex. It is postulated that the lipoprotein serves as a hydrophobic substratum onto which cortical collagen is secreted.