AN66.1-2 | Connective tissue histology — Glossary

The most common resident cell of connective tissue; synthesises collagen, elastic fibres, and ground substance via abundant RER and Golgi apparatus

A modified fibroblast containing alpha-smooth muscle actin that contracts to close wounds; dysregulation leads to keloid formation

A connective tissue cell with metachromatic granules containing histamine and heparin; mediates IgE-dependent hypersensitivity reactions

A phagocytic cell derived from blood monocytes; contains lysosomes and phagosomes; functions in innate immunity and antigen presentation

A terminally differentiated B lymphocyte with clock-face chromatin, abundant RER, and perinuclear hof; secretes immunoglobulins (antibodies)

The most abundant collagen; provides tensile strength; found in skin, bone, tendons, ligaments, and organ capsules

Reticular collagen forming fine networks; found in lymph nodes, spleen, bone marrow, and early wound healing (replaced by type I during remodelling)

Non-fibrillar collagen forming the sheet-like meshwork of basement membranes underlying epithelium and endothelium

Fibres composed of an elastin core surrounded by fibrillin microfibrils; provide recoil and stretch to tissues such as aorta, lungs, and skin

The amorphous gel-like component of the ECM consisting of glycosaminoglycans (GAGs), proteoglycans, and glycoproteins that fills spaces between cells and fibres

Long unbranched polysaccharide chains (e.g., hyaluronic acid, chondroitin sulphate, heparan sulphate) that attract water and create turgor in the ECM

Loose connective tissue with loosely arranged collagen and elastic fibres, abundant ground substance, and multiple cell types; found in subcutaneous tissue and lamina propria

Connective tissue with thick randomly oriented collagen I bundles providing multidirectional strength; found in dermis and organ capsules

Connective tissue with parallel-oriented collagen I bundles providing unidirectional tensile strength; found in tendons and ligaments

Connective tissue composed of type III collagen (reticular) fibres forming a delicate scaffold; supports cells in lymph nodes, spleen, and bone marrow

A change in staining colour from blue to red-purple seen with toluidine blue dye; characteristic of mast cell granules due to their high heparin content

An abnormal scar that extends beyond the original wound margins due to excessive type I collagen deposition by fibroblasts; common in Fitzpatrick skin types IV-VI

An abnormal scar that remains within the wound margins and is self-limiting; distinguished from keloid by its confined extent

A nodular collection of activated macrophages (epithelioid cells) surrounded by lymphocytes; seen in tuberculosis, sarcoidosis, and foreign body reactions

The non-cellular component of connective tissue comprising fibres (collagen, elastic, reticular) and ground substance (GAGs, proteoglycans, glycoproteins)

A type of necrosis seen in blood vessel walls and connective tissue where damaged tissue resembles fibrin; characteristic of rheumatoid nodules and vasculitis

A specialised mucous connective tissue found in the umbilical cord; rich in hyaluronic acid and type I and III collagen

A fat-storing cell; unilocular (white adipose, energy storage) or multilocular (brown adipose, thermogenesis via UCP1)

The pathological replacement of normal tissue by excess fibrous connective tissue (predominantly collagen I); seen in cirrhosis, pulmonary fibrosis, and chronic inflammation