NER VE-ENDINGS. 



305 



not of great value. In the following description the nerve- 

 endings will be taken up according to the tissues in which they 

 occur. 



(1) Intra-epithelial Nerve- endings. 



We can, in the first place, distinguish free nerve-endings (Fig. 

 227), which innervate especially the epithelium of the mucous 

 membranes and epidermis. The nerve fibres run in bundles 

 in the underlying connective tissue up to the margin of the 



HB Free intra- 



riOepithelial 



~-\^H / nerve-endings 





Papilla 



Stratum 

 Malpigkii* 



Medullie<l_\_ 

 nerve fibres I; 



] MerkeVs 

 ^-tactile 

 I corpuscle 



Vertical section through the skin of a pig's snout, which contains free intra-epithelial 

 nerve-endings and Merkel's tactile corpuscles. Stained with gold chloride. X 300. 



epithelium. Here they lose their various sheaths and the 

 naked axis cylinders pass over into the epithelium and break 

 up into fine branches. Such fibres reach often up to the outer 

 layers of the epithelium (e. g., in the epidermis to the stratum 

 grarmlosum) ; in some cases (urinary bladder) they run back 



20 



