44 



TISSUES 



mucin. On filling they resemble a goblet. When 

 the secretion has been discharged these cells become 

 long and slender, the part containing the nucleus 

 extending on either side. They are found in the 

 gastro-intestinal and respiratory tracts. 



FIG. 21 



nut tie by 



Cell body 



Nucleus 



V-Cell membrane 



ijp- Protoplasm 



Xncleus 



Two ciliated cells and two goblet cells isolated from the frog's esophagus. 

 X 520. 



6. Transitional Cells. These are stratified cells be- 

 longing to neither the squamous or columnar groups. 

 They are polygonal; found in the pelvis of the ureter, 

 in the ureter, bladder, the first part of the male and 

 almost the entire length of the female urethra. 



7. Pigmented Cells. These are polygonal or colum- 

 nar in shape, the protoplasm containing pigment. 

 They are found in the epidermis of the colored races, 

 and around the nipple and genitals of the Caucasians, 

 as polygonal cells, and in the retina of the eye where 

 they assume the columnar shape. 



8. Neuro-epithelial Cells. These are cells which have 

 become so differentiated as to perform a special sense 

 function. These are found in the retina of the eye, in 



