i:^ 



cells usually a liltk' sjjiu'c cau he seen, wliich is o! prelly 

 near Ihe same size all oxci-; in oilier woi'ds, Ihe cells arc 

 apparently not in direct contact with i-ach other, but leave 

 open a small space of about one-foui'th [lie size of the cell. 

 By higher magnificalions, il can be seen that the cells are 

 connected by means of protoplasmic processes which are 

 extremely delicate. (Pig. 11. The cytoi)lasm is finely granu- 

 lated sometimes filled with pigment. The nucleus usually 

 contains one large nucleolus. Numerous mitotic figures can 

 be beautifully seen, because of the unicellular layer. (Fig. 

 12.) In many of the surface-grown ei)ithelial cultures the 

 cells arrange themselves in rings and appear as a cross 

 section of a gland; often this glandular arrangement can be 

 seen formed around a giant cell or cells in mitotic division. 

 fFig. 13. Some cultures, when stained, remind oiu' very 

 much of a strongly metaj)las[ic epithelium, as it is known 

 from cei'tain malignant epithelial i)roliferations. All iliffe- 

 rent shapes and sizes of cells can be observed in these 

 cases; sometimes il can be directly seen how quickly the 

 proliferation must have taken place. Such prolifei"alion cen- 

 tres are not unusual and Ihey frequently give an impres- 

 sion that a proliferation of an almost explosive character 

 has taken place, (Fig. 14). N\ e have very frequently found 

 two cells Nvhich had i)ractically not quite separated l)y 

 division before the two new cells showed new mitotic figures. 

 Many stages of amitotic cell division can be seen in the 

 cultures. When the culture of epithelium gets older, i. e., 

 not transferred into a new medium after forty-eight hours, 

 but allowed to remain in the same culture medium for a 

 longer time, the cells can be seen with big vacuoles and 

 often filled with pigment. At the same lime giant cells 

 appear. These cells may contain 10 — 15 nuclei and are many 

 times larger than the normal cells. Around such a giant 

 cell normal epithelial cells can be seen in fairly regulai' 

 circular arrangement. 



