Light and scanning electron microscopic studies on the esophageal spines in the Pacific ridley turtle, Lepidochelys olivacea.

The peculairly specialized esophagus of the Pacific ridley turtle, Lepidochelys olivacea, was described by light and scanning electron microscopic studies. The esophagus is lined by a stratified squamous epithelium with remarkable keratinization, and its major part forms a number of large spines which have been called "pharyngeal teeth." The epithelium consists of three strate: stratum germinativum, stratum spinosum and stratum corneum. The surface of the spine is covered by a scaly keratin of possibly sloughing cells, and the cornified layer on the spine is very thick (more than 100 mu), reaching 3 to 7 times the depth of the corresponding layer in other parts. This peculiar structure in the marine turtle without toothed jaws prabably is used for breaking food into small pieces.