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PRACTICAL HISTOLOGY. 



[XIV. 



LESSON XIV. 

 BONE AND ITS DEVELOPMENT. 



BONE is developed either in connection with cartilage or membrane. 

 The former is called endochondral and the latter intramem- 

 branous ossification. With the exception of a part of the skull 

 its sides and vault and nearly all the facial bones, all the bones 

 are laid down in hyaline cartilage. 



1. Development of Bone T.S. of Fostal Bone. Decalcify the 

 shaft of. the femur or other long bone, e.g., the radius and ulna, 



FIG. 155. T.S. Radius and Ulna of an Embryo Dog. I- Interosseous ligament ; p. Peri- 

 osteum ; me. Medullary cavity ; insp. Subperiosteal tissue; lo. Osseous trahecuhu ; 

 n. Point where the ligament enters the bone ; n'. Union of ligament with the perios- 

 teum. Observe that at first the interosseous membrane is inserted into a depression 

 in the bone ; when the membrane becomes ossified a ridge is formed. 



of a newly-born kitten in picric acid (p. 37). Make transverse 

 sections, and stain them with picro-carmine. Mount one in 

 Far rant's solution. 



(a.) (L) Observe the periosteum (fig. 156, a, &), composed ex- 

 ternally of connective tissue, with fusiform corpuscles stained red. 

 Under this, one or more layers of cubical or somewhat flattened 

 nucleated cells, osteoblasts (<"). They pass into and line the Haver- 

 sian spaces, thus reaching the cancelli and medullary cavity, which 



