Histology Guide virtual histology laboratory

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Histology Guide

Chapter 2 - Epithelium

Epithelium are sheets of cells that cover the externel surface and line the internal surfaces of the body. It is classified by the shape of the surface cells and whether it has a single or multiple layers of cells. All epithelia make a basement membrane that forms a boundary between it and the underlying connective tissue.

Epithelial cells are polarized. Basal refers to those cells or parts of cells next to the basement membrane. Apical refers to those cells or parts of cells found next to the free surface or lumen.


Fig 008 Epithelium

It is not necessary to learn the names of specific tissues for this chapter, but rather learn to recognize variations in epithelia.

Simple Squamous Epithelium

A simple squamous epithelium consists of a single layer of flattened cells. It often occurs at sites of metabolite, fluid or gas exchange across or between cells.

EM 072 Mesothelium

EM 073 Endocardium

EM 080 Bowman's Capsule

Simple Cuboidal Epithelium

A simple cuboidal epithelium consists of a single layer of cells of similar height and width. It may simply serve as linings in ducts or be structurally adapted for secretion or absorption.

EM 074 Interlobular Duct

Simple Columnar Epithelium

A single columnar epithelium consists of a single layer of cells that are taller than they are wide. It is primarily associated with secretion and absorption.

Cilia and Microvilli

EM 077 Respiratory Epithelium

EM 097 Cilia

EM 093 Microvilli

EM 301 Microvilli

Small intestine

EM 017 Small Intestine

EM 034 Small Intestine

EM 079 Brush Border

EM 298 Intercellular Junctions

EM 069 Intercellular Junctions

EM 065 Gap Junctions


EM 082 Gallbladder

EM 081 Gallbladder

EM 078 Gallbladder

EM 075 Gallbladder

EM 083 Gallbladder

Pseudostratified Epithelium Epithelium

A pseudostratified columnar epithelium can appear stratified because: (1) not all cells reach the surface, (2) the nuclei appear at different levels and (3) the cells appear closely packed due to varying cellular shapes. However, it is a form of a simple columnar epithelium since all the cells rest on the basement membrane.

EM 076 Respiratory Epithelium

EM 070 Respiratory Epithelium

Stratified Squamous Epithelium

A stratified squamous epithelium has two or more layers of cells. Only the basal layer of cells rests on the basement membrane. Its name arises from the squamous appearance of the surface layer of cells.

EM 084 Thin Skin