14 



ADVANCED PHYSIOLOGY 



A study of the organs and tissues of an organism as seen 

 with unaided eye is called a study of its macroscopic anatomy. 

 If a microscope is used, one is said to 

 be studying its microscopic anatomy. 



MICROSCOPIC ANATOMY 



After the invention of the micro- 

 scope by two Dutchmen, Hans and 

 Zacharias Janssen, about the year 1600, 

 curiosity gradually led to the examina- 

 tion of all kinds of animal and plant 

 substances under high magnification. 

 Of special interest to us here is a fact 

 established in 1838-1839, that all tis- 

 sues in plants and animals are made up of definitely formed 

 parts or units, somewhat in the manner in which the walls of 

 brick buildings are made up of separate bricks. 



FIG. 4. CARTILAGE 



CELLS 



Embedded in an abundant 

 intercellular matrix. 



A 



BloodVessel ~ 



FIG. 5. THE MICROSCOPIC STRUCTURE OF BONE 



A, cross section; B, longitudinal section; C, a single young bone cell. 



These small units had been seen two hundred years earlier and 

 at that time were called cells, since it was thought that they were 

 practically empty pockets. But to Schleiden and Schwann, 

 who first demonstrated that all tissues are made up of such 



