GENERAL HISTOLOGY 



69 



liver, kidney and sweat glands of man; to the acinous belong the salivary 

 glands, not only of vertebrates, but also of arthropods and molluscs. 



FIG. 31. Tubular glands (after Toldt). A, glands of Lieberkiihn from the 

 human intestine; A', of the conjunctiva of the eye; B, of the cat's stomach; C, from the 

 medullary pyramids of the dog's kidney; D, from the cortex of the rabbit's kidney. 



Sexual Epithelium. The sexual cells may be considered in connec- 

 tion with glandular epithelium. As the secretion of some glands must 

 be expelled from the body, so the sexual cells are elements which must 



FIG. 32. Acinous salivary gland of the aph'd Orthezia catapliractti ('after List). In 

 some acini the nuclei and boundaries of the cells are shown. 



reach the exterior in order to perform their function. Just as the 

 gland-cells are usually scattered among ordinary epithelial cells, so 

 the sexual cells almost invariably lie imbedded in epithelium of the skin 



