Foundations - Introduction to Histology

From CellBiology



A tissue is a functional aggregation of similar cells and their intercellular materials that combine to perform common functions. An organ is an anatomically discrete structure (e.g. heart, skin) with 1 or more functions. Four tissues are considered basic or primary: epithelial, connective, muscular and nervous. Many organs contain all 4 types of tissues e.g. skin (covering, packing, muscles, nerves).

Specific Objectives

  1. Obtain an understanding of the histological appearance of the basic tissues namely epithelium, connective tissue, muscle and nervous tissue.
  2. To examine unique cellular characteristics of each of the basic tissues.

Learning Activities

Virtual Slides Introduction to Histology: Cells and Tissues


Epithelium forms continuous layers of cells that cover surfaces and line cavities of the body.

Activity 1 Simple Epithelium - Gallbladder

Activity 2 Stratified Epithelium - Oesophagus

Links: Blue Histology - Epithelia


Glandular epithelia are aggregates of epithelial cells clustered together to perform a specific secretory or excretory function.

Activity 3 Glands - Skin

Links: Blue Histology - Glands

Connective Tissue

Connective tissues (CT) are the supporting framework for all tissues and organs of the body.

Activity 4 Connective Tissue - Lymph node-silver stain, Lymph node (H&E) and Skin, Hyaline cartilage, Decalcified rib.

Links: Blue Histology - Connective Tissues


Muscle cells (fibers; the cell is longer than wide) produce force which can be used for movements such as locomotion, contraction of organs (e.g. bladder) and pumping movements of the body.

Activity 5 Skeletal-smooth-cardiac muscle and Tongue- circumvallate papillae.

  • Identify the type of muscle found in these virtual histology slides.
  • Locate the muscle cell nuclei and banding pattern (striations) in the muscle cells, identify bundles (fascicles) of muscle cells.
Links: Blue Histology - Muscle | IOWA Virtual Slidebox

Nervous Tissue

The brain and spinal cord comprise the central nervous system (CNS). The nerves that emerge from the spinal cord and brain to pass to parts of the body are the peripheral nervous tissue (PNS).

Activity 6 Peripheral Nerve.

Links: Blue Histology - Nervous Tissue

Additional Information

Histology Stains


  • Stains cytoplasm pink to red; red blood cells are also bright red.
  • Common counterstain to hematoxylin.
  • Stain intensity varies with the formula as well as the fixative.


  • Stains nuclei blue to dark-blue.
  • Stains the matrix of hyaline cartilage, myxomatous, and mucoid material pale blue.
  • Stains myelin weakly but is not noticeable if combined with eosin stain.

Silver Impregnation

  • Stains collagen grey/brown.
  • Stains reticular fibres (type III collagen) black.

Histology Terminology

  • Parenchyma - functional cells
  • Stromal - structural cells, connective tissue
Histology terminology cartoon.jpg Epithelia cartoon.jpg Epithelia cartoon 2.jpg

Electron Microscope Images

Bronchiolar epithelium 3 - SEM.jpg

Bronchiole epithelium ciliated and non-ciliated cells.