X-RAY MICROSCOPY 



Fig. 7. Microangiogram showing the pial ar- 

 teries, veins and capillaries on the surface of the 

 human brain. The small club-like projections rep- 

 resent the commencement of cortical and trans- 

 cerebral arteries which descend vertically into the 

 brain substance. Foetus CR.14.5. X5.5 



cortical, transcerebral and central vessels of 

 the cerebral microcirculation have been so 

 recorded (14), for example the coarse dis- 

 tributor network and fine capillary bed 

 formed by the pial vessels on the brain sur- 

 face, as well as the myriads of small trans- 

 cerebral arteries which arise therefrom to 

 traverse the entire thickness of the brain 

 (Fig. 7). These last terminate in a subepen- 

 dymal capillary plexus about the central 

 cavity or lateral ventricle of the brain (Fig. 

 8). The vessels contributing to the intra- 

 spinal circulation such as the radicular, pe- 

 ripheral and central arteries of the spinal 

 cord have been similarly recorded (Fig. 9). 

 The blood supply of human peripheral 

 nerves, such as the sciatic nerve and its 

 branches, has also been studied by projec- 

 tion microscopy. The vessels (arteriae nervo- 

 rum) contributing to the extraneural and 

 intraneural vascular pattern can be easily 



traced by taking successive micrographs 

 along the length of the nerve trunk. The in- 

 traneural arterioles and capillaries, by re- 

 peated division and anastomosis, form a con- 

 tinuous network along the length of the 

 nerve. In view of the size and multiplicity 

 of these vessels it is not surprising that pe- 

 ripheral nerves bleed when severed. 



The vascular pattern of developing and 

 adult dental pulp vessels of the human tooth 

 can be demonstrated by both contact (15) 

 and projection methods (16), and viewed 

 stereoscopically, without destruction of the 

 vessels such as occurs in histological section- 

 ing. The vessels within the foetal jaws and 

 dental germs are prepared by retrograde 

 aortic injection with Micropaque at low 

 pressure, prior to excision of both foetal 

 jaws and removal of the contained dental 

 germs for x-ray microscopy. The dental pulp 

 vessels of the extracted adult human tooth 

 can be filled with Thorotrast by suction in- 



FiG. 8. Microangiogram of human brain show- 

 ing the long transcerebral arteries passing through 

 the brain substance and terminating in a sub- 

 ependj'mal capillary plexus about the lateral ven- 

 trical. X17 



634 



