(g) 





Fig. 2-1 (5^) 



Fig. 2-1 . Cells derived from the nervous system, (a) Typical motor 

 nerve cell with branched dendrites (de), cell body with Nissl bodies 

 (n.b.) in cytoplasm, nucleus (nu) w4th nucleolus, and long axon 

 (ax) branching to motor end-plates (mot.e.p.) on muscle fibres 

 (m). (b — d) Neurosecretory cells with stainable granules (gr) : (b) 

 with dendrites, from supraoptic nucleus of dog (after Scharrer and 

 Scharrer, 1954ft); (c) wdthout dendrites, the blunt axon is swollen 

 with secretory granules that pass to a blood vessel (b.v.) from gang- 

 lionic-X-organ of crab, Sesarma (after Enami, 1951). {d) cell with 

 shorter axon, from epistellar body of Eledone (after Young, 1936). 

 All drawn roughly to upper scale, ie) and (/) Gland cells with secre- 

 tory granules (s.g.) but no histological characters of neurons (drawn 

 to lower scale) : {e) cells from corpus cardiacum of beetle, Hydrous 

 (cf. Fig. 2-9 after de Lerma, 1956); (/) cells round blood space 

 (b.v.) from adrenal medulla of a tetrapod, with "chromaffin" gran- 

 ules (e.g.) (after Maximow and Bloom, 1942). The differences in 

 quantity of secretion are not characteristic of these cells, but 

 indicate different phases of secretion (cf. Fig. 2-2). {g) Electron 

 micrograph of a highly enlarged section across the axon of a 

 neurosecretory cell from the neurohypophysis of a cat, showing 

 fine granules (Gr) 0.1 to 0.3 [x in diameter, and mitochondria 

 (Mit) that are larger (from Bargmann, 1958). 



