HISTOLOGY BY THE PROJECTION MICROSCOPE 







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Fig. 2. X-ray micrograph showing the terminal 

 ramification of the subrnaxillarj' gland in the rat. 

 Note the conglomerate appearance of the acinar 

 cells and dark radiolucent cells of the granular 

 tubules. Mag. X185 



as the formation of the cell cords and fol- 

 licles. 



General microscopic structure, such as the 

 glomerular and tubular pattern of the kid- 

 ney, is readily recorded and in addition, even 

 unstained sections reveal cj^tological features 

 such as the distinctive cells of the collecting 

 tubules and brush border of the proximal 

 convoluted tubules. 



Mineralized tissues, such as developing 

 teeth, cartilage and bone are well suited to 

 study by projection x-ray microscopy, yield- 

 ing contrasty micrographs. Both low and 

 high power views of ordinary or decalcified 

 bone can be obtained, and the mineraliza- 

 tion process and cells connected with osteo- 

 genesis readily studied. The region of the 

 epiphyseal disc, for example, shows the zone 

 of young proliferating cartilage, with its col- 

 umns of wedge shaped cartilage cells sepa- 

 rated by bundles of collagen fibers, giving 



way to the zone of maturing and calcified 

 cartilage, where the large cartilage cells 

 undergoing dissolution are separated by par- 

 titions of calcified intercellular substance. 

 Osteoblasts can be seen lining the adjacent 

 marrow spaces, and also bone newly laid 

 down on the persisting cores of cartilage 

 matrix in the process of trabecular forma- 

 tion (Fig. 3). The blood vessels and other 

 contents of the marrow spaces can be re- 

 corded, and fully formed and developing 

 Haversian systems, as well as the trabecu- 

 lar patterns of normal and pressurized bone, 

 can be clearly visualized. 



The x-ray projection microscope is a par- 

 ticularly versatile laboratory instrument 

 many applications of which have yet to be 

 explored. It is particularly suited to micro- 

 angiography and microlymphangiography, 

 providing a good method of studying the 



Fig. 3. X-ray micrograph showing the epiphys- 

 eal growth zones at the proximal end of decalci- 

 fied rabbit tibia. Young, maturing and calcifying 

 cartilage is seen, also marrow spaces, osteoblasts, 

 and newly formed bone. The blood vessels in the 

 marrow spaces contain Micropaque. 



585 



