SUSTENTACULAR CONNECTIVE TISSUE. 



195 



is a compound racemose gland, of the fatty type (secreting 

 also a serous and albuminous fluid), and is situated in the 

 subcutaneous tissue. It is divided by septa into fifteen to 



FIG. 74. 



Secreting alveoli of mammary gland of guinea-pig during lactation (Michaelis). 



twenty lobes, and these again into lobules, each of which is 

 made up of a number of the ultimate alveoli (Fig. 74). 



Each of the lobes has a separate outlet-duct opening at the 

 nipple, each lobe thus being essentially a distinct gland. 



The sustentacular connective tissue consists of interlobar 

 septa, interlobular septa, and a small amount of interalveolar 

 connective tissue lying between the alveoli. Adipose and 

 areolar tissue is also abundant, filling the intervals between 

 the lobes and lobules. 



The ultimate secreting alveoli are large oval or elongated 

 saccules, with large open lumina, and are lined with a layer 

 of granular spheroidal epithelium-cells, which secrete the 

 milk. Within these cells globules of oil develop and are 

 discharged into the lumen to form the fat-particles of the 

 secreted milk. 



The alveoli empty into ducts, called lactiferous or galac- 



