ZONE OF CARTILAGE I'll 

 EROSION 



ARTICULAR CARTILAGE 



Ul APH YSIS 



PERIOSTEUM 



Fig. 324. Development of long bones of the appendages. (B and E have been modified 

 to show conditions present in the fore- and hind appendages at about 8 weeks. For de- 

 tailed description of limb development consult Bardeen, '05, Am. J. Anat., 4; Lewis, '02, 

 Am. J. Anat., 2.) (A) Forelimb at II mm. (B) Forelimb at about eighth week, 

 showing centers of ossification in humerus, radius and ulna. (C) Hindlimb at II mm. 

 (D) Hindlimb at 14 mm. (E) Hindlimb at about eighth week, showing centers of 

 ossification in femur, tibia, and fibula. 



The heavy strippling in A, C, D represent centers of chondrification; the black areas 

 in B and E portray ossification centers within cartilaginous form of the long bones. 



F-J represent stages in joint development. 



692 



