Assertion: epithelium's layer | /r/HasProperty | exterior
Facets:
Source sentences:
text: In this particular case, the most apical layers (exterior) of cells are dead and lose their nucleus and cytoplasm, instead contain a tough, resistant protein called keratin.
text: In keratinized epithelia, the most apical layers (exterior) of cells are dead and and contain a tough, resistant protein called keratin.
text: In keratinized epithelia, the most apical layers (exterior) of cells are dead and lose their nucleus and cytoplasm.