Chap. XLIII.] THE DUCTLESS GLANDS. 341 



more commonly, elongated, masses of epithelial cells. 

 The cells are polyhedral or cylindrical, each with a 

 spherical or oval nucleus. In some animals as the 

 dog, horse the cells are thin and columnar, and 

 arranged in a transverse manner. Occasionally a sorfc 

 of lumen can be discerned in some of these cell masses. 



501. Next follows the middle zone, or zona 

 fasciculata. This is the most conspicuous and 

 broadest part of the whole gland. It consists of 

 vertical columns of polygonal epithelial cells, each 

 with a spherical nucleus. The cell substance is trans- 

 parent, and often contains an oil globule. The columns 

 anastomose with their neighbours. Between the 

 columns are fine septa of connective tissue carrying 

 blood capillaries. 



Between the cell columns and the connective septa 

 are seen here and there lymph spaces, into which lead 

 fine channels, grooved out between some of the cells of 

 the columns. 



502. Next follows the inner zona, or zona reticu- 

 laris, composed of smaller or larger groups of poly- 

 hedral cells, with more or less rounded edges. These 

 cell-groups anastomose with one another. The indi- 

 vidual cells are slightly larger, and their substance is 

 less transparent than those of the zona fasciculata. In 

 the human subject they are slightly pigmented. 



503. In the medulla we find cylindrical streaks 

 of very transparent cells ; the streaks are separated by 

 vascular connective tissue. The cells are polyhedral, 

 columnar, or branched. These cell-streaks anasto- 

 mose with one another, and are directly continuous 

 with the cell-groups of the zona reticularis of the 

 cortex. 



504. The cortex is richly supplied with dense 

 networks of capillary blood-vessels ; their meshes are 

 polyhedral in the outer and inner zone, elongated in 

 the middle zone, or zona fasciculata. In the medulla 



