XXVl] DUCTLESS GLANDS 203 



staining cells, generally peripherally placed, and smaller cubical 

 or columnar cells ; here and there, especially at the outer portion, 

 stained secretion may be seen in the lumina of the tubes. 



Note in the posterior lobe (a) the central rather fibrous 

 mass with scattered nuclei and some angular cells, forming the 

 nervous or infundibular portion, (b) the glandular investment, 

 consisting of polyhedral or cubical cells arranged in clumps, or 

 anastomosing columns, or forming tubes. 



4. Section of supra-renal body of cat 1 , cut trans- 

 versely to its long axis. (Flemming's fluid, cut frozen.) 

 Stain with hsematoxylin (better with Ehrlich-Biondi 

 fluid). Note 



The thin connective tissue capsule. 

 The cortex, consisting of bands of cells stretching 

 inwards from the capsule. The medulla fairly sharply 

 marked off from the cortex; it consists of a network 

 of rather tubular-looking cell-masses, and generally 

 shows some conspicuous, thin-walled veins. 



If stained with Ehrlich-Biondi fluid, the cortex will be a darker 

 red than the medulla ; if the gland is hardened in mercuric chloride 

 and stained with picrocarmine the cortex will be yellowish, and the 

 medulla red. 



5. Distinguish the zones of the cortex, viz. (1) an outer 

 narrow zone, the zona glomerulosa, consisting of cylinders of cells ; 

 at right angles to the surface there are usually two elongated 

 cells from side to side of the cylinder, and the nuclei are nearer the 

 centre than the basement membrane ; (2) a broad zone, zona 

 fasciculata, consisting of cell-columns continuing the line of the 

 cylinders but for the most part having a single row of polyhedral 

 cells. (The arrangement resembles somewhat that of the liver 

 cells.) The columns here and there communicate ; (3) a narrow 

 zone, the zona reticulata, consisting of a cell-plexus, generally 

 two cells from side to side of a strand ; the cells are polyhedral 

 and smaller than those of the preceding zone. 



1 The appearance varies somewhat in different mammals. 



