Mystery of biology 8 : Polarity in epithelial cells & tissues.

POLARITY IN EPITHELIAL CELLS

Epithelial tissue has it's own unique role in metabolic activities as well as in lining the inner wall of several organs. Amazing fact is cells in constituting the epithelial tissues are NOT identical.

SQUAMOUS EPITHELIUM

CILIATED EPITHELIUM

There are two types of cells in epithelial tissue..; namely, 

1.       Polarized epithelial cells
2.       Non polarized epithelial cells.

Polarized epithelial cells form boundaries between an external or luminal compartment and the extracellular fluid compartment. The biological roles of these cells relate to their location between compartments. First, sheets of polarized epithelial cells form barriers of very selective permiability between compartments. Secondly, they regulate the composition of the two compartments by carrying out specialized vectorial transport between the compartments, manifest as absorption, transcytosis and secretion.

                  The fundamental characteristic of polarized epithelial cells is organization of its plasma membrane into structurally and functionally distinct domains. 

         Whereas in non polarized cells, it's plasma membrane is not well organized into distinct domain, they exhibits indistinct characteristic features.

UPPER ONE IS NON POLARIZED LOWER ONE IS POLARIZED

UPPER ONE IS NON POLARIZED LOWER ONE IS POLARIZED

Polarity plays an important role in accurate functioning of tissue...

Very important point here is, similar to these epithelial cells, even in plant tissue polarity has been observed and is very much distinct when compared to animals.