Histology Guide

virtual histology laboratory

Chapter 3 - Connective Tissue

Connective tissue supports and protects organs. It has three primary components: fibers, extracellular matrix and cells. The composition of these elements is the basis of which connective tissues are classified.

This chapter examines the basic types of connective tissue, while subsequent chapters examine specialized connective tissues such as cartilage, bone and blood.


Mesenchyme is an early form of connective tissue found in embryos. Mesenchymal cells can differentiate into other cell types such as fibroblasts, fat cells, cartilage and bone.

MH 020a Fetal Pig Snout

MHS 241 Umbilical Cord

Connective Tissue Fibers

Connective tissue contains three types of fibers: collagen, elastic and reticular.

MH 024-025-026 Mesentery

(H&E / azan / Verhoeff)

MH 078 Lymph Node



Connective tissue is classified based on the density of fibers (loose or dense), the arrangement of fibers (irregular or regular) and the predominate fiber or cell type.

MH 021-022-023 Connective Tissue

(H&E / azan / Verhoeff)

Loose Connective Tissue

Loose (areolar) connective tissue has a sparse and random arrangement of fibers.

MH 024 Mesentery

MH 260 Mesentery

Dense Regular Connective Tissue

Dense regular connective tissue contains many collagen fibers arranged in parallel bundles.

MH 029a Tendon

Dense Irregular Connective Tissue

Dense irregular connective tissue contains collagen fibers that are more randomly arranged.

MH 091 Thick Skin


Although connective tissue has fewer cells than most tissues, the cells found in connective tissue are still important. Fibroblasts and adipocytes do not leave connective tissue.


Fibroblasts are widely distributed within connective tissue and synthesize the components of the extracellular matrix. They are also capable of differentiating into other types of connective tissue cells.

MH 020a Fetal Pig Snout

MH 021 Connective Tissue

MHS 227b Eye


Adipocytes (or fat cells) are specialized for the synthesis and storage of lipids. They may occur singly but are more often found as clusters within loose connective tissue.

MH 021 Connective Tissue

MHS 213 Lymph Nodes



Neutrophils, eosinophils, basophils, lymphocytes, and monocytes are immune cells that migrate from the blood into connective tissues.


Eosinophils are involved in many inflammatory processes, including parasitic infections, allergic diseases, and asthma.

MH 094 Parotid

Mast Cell

Mast cells are widely distributed in connective tissue. They release molecules that dilate blood vessels and recruit more immune cells to the site of an infection.

MH 008 Pancreas (aldehyde fuchsin)

MH 003 Toluidine Blue


Plasma Cell

Plasma cells produce large quantities antibodies against specific antigens.

MH 016 Simple Epithelia

(small intestine)


Monocytes differentiate into macrophages within tissues. Macrophages are avidly phagocytic cells that engulf and digest microbes, cellular debris and foreign substances.

MH 024-026 Mesentery