590 



VETERINARY PHYSIOLOGY 



to lie in close juxtaposition and so to constitute a single 

 organ according to anatomical nomenclature. 



I, From the Nervous System. 



1. Chromaffin Tissue (Medulla suprarenalis). 



2. Hypophysis Cerebri. <=- 



II. From the Buccal Cavity. 



3. Thyreoid.^ 



4. Pituitaiv.^-^ 



III. From the Intestine. 



5. Pancreas. 



6. Mucosa of Small Intestine. 



IV. From the Branchial Arches. 



7. Parathyreoids.< 



8. Thymus. 



V. From the Mesothelium of the Genital Ridge. 



9. Gonads. 

 10. Inter-renal Bodies (Cortex suprarenalis). < — 



The pairs which occur in anatomical juxtaposition are indicated 

 by joining lines. 



I. From the Nervous System. 



I. CliromaflB.n Tissue. 



Tliis in mammals is chiefly disposed as the medullary part 

 of the suprarenal bodies. But smaller masses are found along 

 the aorta and some of the large arteries. In fishes it lies 

 entirely separate from the equivalent of the cortex suprarenalis — 

 the inter-renal tissue. 



1. Development. — It is developed from the emigrating cells 

 which form the true sympathetic or visceral system of nerves 

 (p. 54). 



2. Structure. — It consists of rather large irregular cells 

 containing granules which stain of a brown colour with chrome 

 salts — hence the names of the tissue. These cells occupy 

 spaces between large sinusoid capillary vessels. 



3. Physiology. — (I) It is impossible to reTnove the chromaffin 

 tissue in mammals without removing the inter-renal tissue of 



