50 



FOURTH LECTURE. 



posus disappears ; though certain parts, like the orbital cavity 

 and the medulla of the central portion of the hollow bones, 

 still obstinately retain the fatty contents 

 within their cells. 



Adipose tissue is of a secondary nature. 

 It is entirely wanting in the earlier embryo- 

 nic life. The fat cell arises from a metamor- 

 phosis of the cells of the connective tissue. 

 The ordinary flat, lapped and pointed ele- 

 ments of the latter (Fig. 50, a) take up fat 

 drops in increasing quantity (b) ; these flow 

 together, the cell becomes rounder, losing 

 its processes (c), and finally assumes the 

 well-known appearance (d). There is also 

 another coarsely granular connective-tissue 

 cell, to which more attention has only re- 

 cently been called, and which may possibly 

 be transformed into a fat cell. We regard the so called cell 

 membrane as a boundary layer formed from the adjacent 

 connective tissue. 



Fig. 50. — Transfor- 

 mation of the connect- 

 ive tissue corpuscles 

 into fat cells, from a 

 human muscle, serving 

 at the same time as a 

 diagram of the embryo- 

 nic origin. 



