TISSUES, ORGANS, AND SYSTEMS. 



77 



from the middle of the cervix, up the Fallopian tubes, as far as the outer 

 surface of thefanbrite, 



(5.) With rounded ciliated cells (simple ciliated pavement-epithelium). 



Epithelium of the cerebral cavities of embryos. 



b. Epithelium in many layers : 



(1.) With cylindrical or rounded cells below, rounded, polygonal, more 

 or less flattened cells above (laminated pavement-epithelium). 



Epithelium of the oral cavity, of the lower half of the pharynx, of 

 the oesophagus, of the lachrymal canals, of the conjunctiva, of the tym- 

 panic cavity, of the vagina and female urethra, of the urinary bladder, 

 of the ureters and pelves of the kidneys, and of certain synovial mem- 

 branes. 



(2.) With rounded cells below, more elongated ones in the middle, and 

 ciliated conical ones above (laminated ciliary epithelium). 



Epithelium of the larynx, trachea, and larger bronchise ; of the nasal 



Fig. 17. 



cavity, with the exception of the regio 

 olfactoria ; of the lachrymal sac and 

 duct; of the upper half of the pharynx. 

 Among the epidermic tissues, we 

 may also enumerate the crystalline lens and the enamel.* The former 

 consists of long tubular cells filled with albumen, which, as the study of 

 development teaches, are formed by the metamorphosis of a part of the 

 epidermis. The latter contains prismatic, densely-ossified long fibres, 

 which, in all probability, are also nothing more than excessively elon- 

 gated epithelial cells of the enamel organ of the embryonic tooth sac. 



The epidermic tissue is found through almost the whole animal king- 

 dom, and as regards its elements, it exhibits no very considerable devia- 



FIG. 17. A simple papilla with manifold vessels and epithelium, from the gums of a 

 child ; magnified 250 diarn. 



Fig. 18. Ciliated epithelium from the trachea of a man; magnified 300 diam.; a. outer- 

 most part of the elastic longitudinal fibres ; 6, homogeneous outermost layer of the mucous 

 membranes; c, deepest round cells ; rf, median long cells; e, outermost ciliated cells. 



* [Vide infra, note on the Teeth.] 



