Bone and cartilage

Histology of Bone and CartilageDr. Sama ul HaqueUnderstand the histology of bone.

Understand the histology of cartilage.

ObjectivesComposition of BonesCollagen: chief organic constituent (protein)Inorganic Calcium Salts: Vitamin D essential for absorption

A Chemical Analysis of Bone

Cells Osteoblasts: bone building, bone repairing cells in the periosteum and synthesize new matrix (Osteogenesis)

Osteocytes: osteoblast embedded within the bone matrix (mature bone cells)

Osteoclasts: cells that cause absorption of bone or dissolve bone matrix (Osteolysis)

PeriosteumDense, fibrous membrane covering bone

Contains blood vessels

Essential for bone cell survival and bone formation

Endosteum

Histological or MicroscopicallyCompact bone (dense)

Basic unit of compact bone is an osteon.

Osteocytes within lacunae arranged in concentric circles called lamellae.

This surround a central canal; complex is called Haversian system.

Weight Bearing.

Histological or MicroscopicallySpongy bone (cancellous)Contains trabeculaeFound at ends of Long Bones, Ribs, Sternum, Hips, Vertebrae, CraniumWeb-Like ArrangementLow Stress Areas Where Weight of Bone Would Be a Problem.

Compact and Spongy Bone

Compact and Spongy Bone

Compact and Spongy BoneOsteoblasts and Osteocytes

Lacunae and Canaliculi Communication

Periosteum and Endosteum

Mature Bone (Compact)

Mature Bone (Spongy)

Osteon

Lacunae (L)Canaliculi (C)Osteocytes (O)

CartilageType of Dense connective tissue ( Cells and fibers)

Perichondrium ( Fibro-vasculo-cellular membrane)

Cells = Characterized by Rigid with flexibility and Resilience. Avascular

Nerves and lymphatics are absent

Cells (Chondroblasts and chondrocytes)

Matrix => Connective tissue fibers (Collagen, Elastin)

Hyaline Cartilage Hyaline (Glass) Commonest form Bluish white, translucent and homogenous in appearance with collagen fibers. Sites:=> Articular cartilage=> Costal cartilage=> Tracheal cartilage

Ossifies to form bone in young age

Hyaline Cartilage and Perichondrium

Elastic Cartilage Yellow; Elastin fibers More elastic than hyaline Sites:=> Pinna of the ear=> Epiglottis=> Auditory tube Never ossifies

Elastic CartilageFibro-cartilage White, Opaque with collagen fibers Sites=> Intervertebral disc=> Intra articular disc => Menisci Ossifies in old age

Collagen (c)

Fibrocartilage Cartilages

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