HISTOLOGY 



97 



Most types of receptor neurons are epithelial. In some of these 

 the receptor cell itself produces a nerve fiber which conducts to the central 



Fig. 91. — Types of nerve cells. A, multipolar cell; B, portion of nerve fiber with 

 sheaths; C, unipolar cell (such a cell may arise by modification of a bipolar cell as shown 

 in Fig. 93); D, pyramidal cell (from cerebral cortex), a, axon; c, collateral; cb. cell- 

 body; d, dendrites; m, medullary sheath; n, nucleus of cell of Schwann's sheath; r, node 

 of Ranvier; s, sheath of Schwann; t, telodendron. (From Kingsley.) 



Fig. 92. Cell-bodies of neurons showing arrangement of neurofibrils. .4, from 

 human spinal ganglion; two cut fragments of the neuraxon lie near the cell-body. B, 

 "giant pyramidal cell" from human cerebral cortex. Highly magnified, a, neuraxon. 

 (From Morris, "Human Anatomy.") 



organ— e.g., an olfactory cell and its fiber (Figs. 83C, 3485). In 

 such cases, one neuron serves as both receptor and conductor. In other 



