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STUDENTS HISTOLOGY 



8. The abrupt transition from columnar to flattened cells in 

 the epithelium of the external os. (a) The shortening of the 

 columnar cells as the point of change is approached. (Sections 

 must be examined until one is found showing this point well. The 

 illustration [Fig. 125] is not exaggerated, and a properly cut and 

 selected specimen must exhibit clearly the last columnar and the 

 adjoining flattened cell.) 



9. The vaginal epithelium (Figs. 125 and 126). (a) That it is 



FIG. 125. EXTERNAL Os OF FIG. 124. MORE HIGHLY MAGNIFIED (X400). 



A. Muscular tissue of the os uteri, with numerous blood-vessels. 



B. Capillary plexuses of subepithelial tissue mucosa. 



C. Ciliated columnar cells covering the os. 



D. Vacuolated cells. 



E. Shortening of the columnar cells preparatory to 



F. Change from typical uterine epithelium ciliated columnar cells to flattened 



stratified cells. 



G. Papillary structure of the niucosa of the external os, after change of epithelium. 



of the stratified squamous variety, (b) The deepest line of cells 

 following the sinuous line formed by sectioning the papillary mucosa. 

 (c) That the cells are more or less flattened. (d) That their 

 edges, excepting those of the surface, are serrated, (e) The 



