62 



HISTOLOGY. 



one lacuna. The lacunae also have increased in size. The matrix in 

 this region stains a deeper blue with haematoxylin than elsewhere, due 

 to the deposition of lime salts within it. On the left a cavity is seen ex- 



Osteogenic 

 tissue. 



Hyaline carti- 

 lage (cells in 

 groups). 



._ 'aline car- 

 tilage (cells 

 ilarged). 



Periosteum. 



Osteoblasts. 



Osteoblasts. Blood 

 vessels. 



Osteoclasts. 



Endochondral bone. 



Marrow 

 cells. 



FIG. 67. FROM A LONGITUDINAL SECTION OP THE PHALANX OP THE FIRST FINGER OP A HUMAN FETUS 



OP FOUR MONTHS. X 220. 



cavated by the perichondral tissue. Several such buds of tissue will form, 

 invading the cartilage from all sides, and uniting in the center of its shaft. 

 The 'calcified matrix of cartilage dissolves before their advance, setting 



