Development of the acinous and accessory salivary glands in Nucella lapillus (Neogastropoda: Muricoidea)

Abstract

The acinous and accessory salivary glands in Nucella lapillus are derived from two distinctly separate sites; the acinous salivary glands evaginate from the walls of the buccal cavity, whilst the accessory salivary glands arise as paired invaginations of the epithelium of the ventral lip of the mouth. During the development of the oesophagus, the acinous salivary glands grow posteriorly and come to lie behind the nerve ring, but are pulled anteriorly through it when the proboscis elongates during development. The ducts of the accessory salivary glands fuse to form a single duct with paired tubular glands during proboscis formation. The secretory cells in both pairs of salivary glands differentiate prior to the crawlaway's emergence from the egg capsule. The ontogeny of the salivary glands in Nucella shows that the accessory salivary glands cannot be homologous with the acinous salivary glands or venom apparatus of the Conoidea.