424 E. T. Bell. 



cords of fibrous tissue. This adipose tissue begins to develop early. 

 In an 11 cm. foetus a small mass of mesenchyme is present l^etween 

 the ventral surface of the sternum and the overlying pectoral muscles. 

 This tissue is present in somewhat greater quantity in a 13 cm. 

 foetus, but no true adipose cells are ytt i)resent. The tissue is some- 

 what reticular in structure. 



A 22 cm. foetus shows a considerable mass of tissue in the situa- 

 tion above described. Little clumps of fat cells are present around 

 the blood vessels. The coarse bundles of fibrous tissue are partially 

 differentiated. In some places there is a considerable amount of 

 preadipose tissue around the nests of fat cells. None of the pre- 

 adipose tissue is sharply marked off from the developing fibrous 

 tissue. 



The tissue which forms the fat of the brisket is not then formed 

 into preadipose tissue until a short time before it is transformed into 

 adipose ; but a somewhat reticular connective tissue is present in this 

 region for some time previous. ^^ 



In its further growth the small masses of adipose tissue formed 

 around the blood vessels increase in size and become crowded together, 

 except where they are separated by the cords of fibrous tissue which 

 characterize this region. 



Subcutaneous preadipose tissue. 



Text Fig. 1 shows the preadipose tissue around the blood vessels 

 of the subcutaneous tissue over the sternum of a 24 cm. foetus. The 

 preadipose tissue is developed to a considerable extent in advance 

 of the fonnation of true fat cells. It seems to be formed only a 

 short time before fat impletion begins. Its structure is similar 

 to that of renal preadipose tissue except that the processes of 

 the cells are somewhat thinner (Text Fig. 6). In the inguinal 

 region, the preadipose tissue forms around the blood vessels as above 

 described, but does not follow them so closely. Larger areas of pre- 



"In the section of the brisket a mass of preadipose tissue was noticed on 

 the internal surface of the sternum in the thoracic cavity. This mass is 

 fairly well-defined and contained no fat cells at 13 cm. It was not studied 

 further. 



