et_07. Transitional epithelium (urothelium)
(Ureter, hematoxylin-eosin)
1. Find the epithelial layer lining the internal walls of the ureter. Study thoroughly the morphpology of the transitional epithelium:
- find the basal layer made up by the tiny cells with dark-colored nuclei, their wider side sticking to the basal membrane;
- the intermediate layer is composed of elongated epithelial cells, their narrower side sticking to the basal layer, the cells are arranged tile-like one row over another;
- the superficial layer makes up the surface and contains large often binuclear cells having dome-like shape (if the wall of the organ is unstretched).
2. Draw and point out:
- I - loose connective tissue,
- II - basal membrane,
- III - transitional epithelium
(1 - basal layer, 2 - intermediate layer, 3 - superficial layer).
3. Define and write significant features of the epithelium and its embryonic origin