Histology · Connective tissue, cartilage and bone
Connective tissue proper: cells and fibres !
- Tissue
The tissue that binds and supports the body: a few cells scattered in a matrix of fibres and gel.
Updated 2026-11-01
See it in 3D: Skin · Achilles tendon · Patellar tendon
What it is
Connective tissue is defined by abundant extracellular matrix and relatively few cells, the opposite of epithelium. Connective tissue proper is divided into loose (areolar) tissue, which supports epithelia and vessels, and dense tissue, irregular in the dermis and organ capsules or regular in tendons and ligaments. Its fibroblasts build the matrix; its wandering immune cells defend it.
Key facts
- Fibroblasts make collagen, elastin and ground substance; resting forms are called fibrocytes.
- Macrophages come from blood monocytes and clear debris and microbes.
- Mast cells hold granules of histamine and heparin and drive immediate allergic reactions.
- Plasma cells, lymphocytes and eosinophils pass through, especially in the gut lamina propria.
- Elastic fibres (elastin on a fibrillin scaffold) let skin, lungs and large arteries recoil; they stain with orcein or Verhoeff, not well with H&E.
- Collagen synthesis needs vitamin C to hydroxylate proline and lysine.
Structure
- Loose (areolar): scattered cells, thin fibres running in all directions and plenty of pale ground substance, as in the lamina propria and submucosa.
- Dense irregular: thick pink collagen bundles in all directions with few nuclei, as in the reticular dermis.
- Dense regular: parallel collagen bundles with rows of flattened fibroblast nuclei squeezed between them, as in tendons.
- Reticular tissue: a mesh of thin type III fibres, seen only with silver stain, forming the stroma of lymph nodes, spleen and marrow.
- Ground substance: glycosaminoglycans (hyaluronic acid), proteoglycans and adhesive glycoproteins that hold water; it washes out in routine sections.
Collagen types to know
| Type | Where | When it fails |
|---|---|---|
| I | Bone, skin dermis, tendon, ligament, dentin, mature scar | Osteogenesis imperfecta (brittle bones, blue sclerae) |
| II | Hyaline and elastic cartilage, vitreous body, nucleus pulposus | Some chondrodysplasias |
| III | Reticular fibres, blood vessel walls, uterus, early granulation tissue | Vascular Ehlers-Danlos syndrome (arterial and bowel rupture) |
| IV | Basal lamina of basement membranes, lens capsule | Alport syndrome; target in Goodpasture disease |
Clinical notes
- Scurvy: without vitamin C collagen is weak, giving bleeding gums, poor wound healing and perifollicular haemorrhages.
- Marfan syndrome: fibrillin-1 defects weaken elastic fibres, with aortic root dilation and lens dislocation.
- Ehlers-Danlos syndromes: defects in collagen or its processing cause stretchy skin, hypermobile joints and fragile tissues.
- Keloids are an overgrowth of dense collagen beyond the edges of a scar.
Test yourself
Think of the answer, then tap the question to see it.
Which collagen type is the main fibre of reticular tissue and early granulation tissue?
Type III collagen; it is later replaced by type I as a scar matures.
How do dense regular and dense irregular connective tissue differ, and where is each found?
Dense regular has parallel collagen bundles (tendons, ligaments); dense irregular has bundles in many directions (dermis, organ capsules).
Why does vitamin C deficiency impair wound healing?
Vitamin C is a cofactor for hydroxylating proline and lysine in procollagen; without it collagen triple helices are unstable and weak.
Which connective-tissue cell stores histamine and heparin?
The mast cell.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Extracellular matrix: collagen types, elastin, ground substance
- Adipose tissue: white and brown fat
- Cartilage: hyaline, elastic, fibrocartilage
- Bone tissue: cells, compact and spongy bone
- Basement membrane
- Wound healing: phases and scar
Related conditions
Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice.
Sources: 4.3 Connective Tissue Supports and Protects (OpenStax, 2022); Connective Tissue (National Cancer Institute, SEER Training Modules, 2024).
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Representative model, for educational purposes only.