Glands 105 



simple saccular glands found in the human body are a few of the sebaceous 

 glands of the skin. In compound glands the lumen, or inner part of the 

 canal of the glands, is branched ; in many glands the lumen branches re- 

 peatedly, so that the canal structure is very complex. Compound glands 

 may be tubular, saccular, or sacculo=tubular {acino-tubular ; tubo-alveo- 

 lar). The compound saccular glands are often designated as racemose 

 glands. The kidneys and the majority of the gastric glands are compound 

 tubular. The salivary glands 18 and most of the sebaceous glands of the 

 skin, the Meibomian (or tarsal) glands in the edges of the eye-lid, and 

 the mucous glands in the oral, nasal and respiratory passages are compound 

 saccular. 



The pancreas, and Brunner's glands in the small intestine, are types 

 of compound sacculo-tubular glands. The acini (sacs) in these glands are 

 long and narrow like the lumen-branches of the compound tubular glands, 

 but are distinguishably larger in diameter than the ducts into which they 

 discharge. 



The liver is a duct-gland, but it does not belong to either the saccular 

 or tubular classes. In glands of these classes there is a cavity (tube or 

 saccule), or a number of cavities, connected with the same duct, and the 

 secreting cells line these cavities. In the liver the secreting cells are ar- 

 ranged in solid masses (no cavities) and fine branches of the bile duct run 

 everywhere between them. It is therefore classed as a solid gland (Cun- 

 ningham). 



The compound duct-glands are in most cases surrounded by capsules 

 of connective tissue and from this connective tissue, if the gland is very 

 complex, septa extend into the gland, dividing it into lobes and lobules. 

 Each lobe or lobule contains saccules or tubules opening into a common 

 branch of the duct. The secreting cells in the case of the complex glands 

 are confined to the saccules or tubules, the cells of the epithelial lining of 

 the duct proper being non-secreting. In the simple glands the entire lining 

 of the cavity may be secretory, but usually in these also the secreting cells 

 are confined to the deeper part or fundus, the more superficial portion 

 being merely a duct. 



The glands are all supplied with blood vessels and lymph vessels. Most 

 glands are supplied with nerves, in some cases from both the autonomic 

 and the direct cerebro-spinal systems. 



Some of the gland nerve fibres run to the muscular cells of the blood 

 vessels, some to the muscles of the ducts, and some to the secreting cells 



18 According to Cunningham. Howell describes them as tubular; Pierson as tubo- 

 alveolar. 



