(C) Neural crest # MERKEL CELLS, which are believed to be derived from the neural crest, contain many large (50-100 nm) dense-cored vesicles, presumably containing transmitters, which are concentrated near the junction with the axon. F.S. Merkel referred to these cells as Tastzellen or "touch cells" Merkel cells are found in the skin and some parts of the mucosa (stratum germinativum) of all vertebrates. In mammalian skin, they are clear cells found in the stratum basale (at the bottom of sweat duct ridges) of the epidermis approximately 10 pm in diameter. They also occur in epidermal invaginations of the plantar foot surface called rete ridges. Most often, they are associated with sensory nerve endings, when they are known as Merkel nerve endings (Merkel cell-neurite complex). They are associated with slowly adapting (SA1) somatosensory nerve fibers. They are associated with the sense of light touch discrimination of shapes and textures. They can turn malignant and form the skin tumor known as Merkel cell carcinoma.DERIVATIVES OF NEURAL CRESTDerivative of neural crestDeveloping partsNeurons1. Spinal posterior nerve root ganglion (dorsal root ganglia) 2. Sensory ganglia of V, VII, VIII, IX & X cranial nerves 3. Sympathetic gangliaPiamater & Arachnoid mater (Not duramater)--Schwann cellsNeurolemmal sheaths of all peripheral nervesAdrenal medullaChromaffin tissuePigment cells of skinMelanoblasts; Merkel's cells of epidermisMesenchyme of dental papilla & Odontoblasts--Cells from cranial part of neural crest (Somatomeres)Development of musculature of head & in formation of face