Epithelial cells get clues about the nature of their neighbors from:

Zonula adherens or adhering junctions provide such clues to epithelial cells, leading eventually to formation of a coherent epithelium. Zonula adherens and desmosome helps to hold cells together, and the hemidesmosome and focal adhesions attach cells to their basal laminas. The gap junction makes - cytoplasmic "tunnel" for diffusion of small molecules (< 1000 Da) between two neighboring cells.