368 THE PERIPHERAL NERVOUS SYSTEM 



The ciliary ganglion is related by a ramus communicans to the ophthalmic division 

 of the trigeminal nerve and receives fibers from the oculomotor nerve. Its cells 

 are probably derived entirely from the semilunar ganglion. The sphenopalatine, 

 submaxillary, and otic ganglia probably take their origin from migrating cells of 

 the semilunar ganghon, but as they are connected with the geniculate ganghon of 

 the facial nerve, the latter may contribute to their formation. The sphenopala- 

 line ganglion is connected directly with the semilunar ganglion by two com- 

 municating rami. The submaxillary ganglion is intimately related through the 

 mandibular division of the trigeminal nerve to the semilunar ganghon, while the 

 otic ganglion is united to the latter by a plexus and is related to the glossopharyn- 

 geal nerve through its tympanic branch. 



The cervical ganglia lose their segmental arrangement and represent the fusion 

 of from two to five gangha of the cervical and upper thoracic region. The more 

 distally located prevertebral ganglia (of the cardiac, coeliac, hypogastric, and pelvic 

 plexuses) are derived from cells of the neural crest which migrate to a greater dis- 

 tance ventrally (Fig. 366). The visceral ganglia (of the myenteric and submucous 

 plexuses), and the prevertebral cardiac plexus as well, are derived by Kimtz 

 chiefly from migratory cells from the hind-brain and from the vagus gangha. 



The sympathetic nerve cells give rise to axons and dendrites, and are thus 

 typically multipolar cells. Their axons possess a neurilefnma sheath, but remain 

 unmyelinated. 



D. CHROMAFFIN BODIES: SUPRARENAL GLAND 



Certain cells of the sympathetic gangha do not form nerve cells, but are 

 transformed into pecuhar gland cells which produce an internal secretion. The 

 secretion formed by these cells causes them to stain brown when treated with 

 chrome salts, hence they are called chromaffin cells. Cells of this t3^e derived 

 from the ganghonated cord of the sympathetic system give rise to structures known 

 as chromaffin bodies. Chromaffin derivatives of the ccehac plexus, together with 

 mesenchymal tissue, form the anlage of the suprarenal gland, an organ which 

 reaches a relatively large size in human embryos (Fig. 232). 



The Chromaflin Bodies of the ganghonated cords are rounded cellular 

 masses partly embedded in the dorsal surfaces of the gangha (Fig. 367). At birth 

 they may attain a diameter of 1 to 1.5 mm. In number they vary from one to 

 several for each ganglion. 



Similar chromaffin bodies may occur in all the larger sympathetic plexuses. 

 The largest of these structures found in the abdominal sympathetic plexuses are 



