CorpusHuman Anatomy
SkeletalCartilage

Epiphyseal plate

Lamina epiphysialis

Also known as: growth plate, physis, epiphyseal line, epiphyseal cartilage

A disc of hyaline cartilage between epiphysis and metaphysis that produces growth in length of long bones; after puberty it ossifies, leaving the epiphyseal line.

Show on body map Long Bone — Structure

Overview

Closure — girls≈14–16 years (most plates)
Closure — boys≈16–19 years (most plates)
Last to fuseMedial clavicle, iliac crest (≈20–25 years)

The growth plate is a primary cartilaginous joint (synchondrosis) organised into zones from the epiphysis towards the diaphysis: (1) reserve/resting zone — scattered chondrocytes anchoring the plate; (2) proliferative zone — chondrocytes dividing into longitudinal columns ("stacks of coins"); (3) hypertrophic (maturation) zone — cells enlarge ten-fold and secrete type X collagen and VEGF; (4) zone of calcification — matrix calcifies and chondrocytes die; (5) zone of ossification — invading capillaries and osteoblasts deposit bone on the calcified cartilage spicules. Because cartilage is added on the epiphyseal side as fast as it is replaced on the diaphyseal side, the plate stays about the same thickness while the bone lengthens.

Growth stops when chondrocyte proliferation ceases and the plate is replaced by bone (epiphyseal closure), under the influence of oestrogen in both sexes. Closure occurs earlier in girls (≈14–16 years for most plates) than boys (≈16–19 years); the last to close are the iliac crest, medial clavicle and ischial tuberosity (≈20–25 years). Skeletal (bone) age is estimated from an X-ray of the left hand and wrist.

Location

Between epiphysis and metaphysis of growing long bones.

Parts & subdivisions

  1. Zone of reserve (resting) cartilage
    Small, scattered chondrocytes; stem-like pool.
  2. Zone of proliferation
    Columns of flattened dividing chondrocytes — target of GH/IGF-1; defective in achondroplasia.
  3. Zone of hypertrophy
    Enlarged, glycogen-rich chondrocytes; signal vascular invasion.
  4. Zone of calcification
    Matrix calcifies, chondrocytes undergo apoptosis (zone of provisional calcification).
  5. Zone of ossification
    Osteoblasts lay bone on calcified cartilage — the primary spongiosa of the metaphysis.
  6. Epiphyseal line
    Bony remnant of the fused plate visible on adult X-rays and sections.

Anatomy

Histology

Hyaline cartilage with columnar chondrocytes; the hypertrophic zone is the weakest mechanically.

Function

  • Longitudinal (interstitial) growth of long bones
  • Determines final adult height and limb proportions
Regulation

GH and IGF-1 (proliferation), thyroid hormone (hypertrophy), PTHrP–Indian hedgehog feedback loop (pacing), oestrogen (closure), vitamin D (calcification).

Clinical significance

Salter–Harris fractures

Children’s fractures through the plate usually pass through the weak hypertrophic zone. Type II (through plate and metaphysis) is commonest; types III–V involve the germinal layer or articular surface and risk growth arrest and angular deformity.

Achondroplasia

Gain-of-function FGFR3 mutation suppresses chondrocyte proliferation → short limbs; intramembranous bone (skull vault) grows normally.

Gigantism vs acromegaly

GH excess before plate closure increases height (gigantism); after closure only appositional growth occurs (acromegaly — enlarged jaw, hands, feet).

Test yourself

In which zone of the epiphyseal plate do chondrocytes form longitudinal columns by mitosis — the zone affected in achondroplasia?
  1. Reserve (resting) zone
  2. Proliferative zone
  3. Hypertrophic zone
  4. Zone of calcification

Answer: Proliferative zone

Chondrocytes divide in the proliferative zone, forming stacked columns. Activating FGFR3 mutations in achondroplasia inhibit this proliferation, shortening the long bones while intramembranous growth is unaffected.

In a child, haematogenous osteomyelitis of a long bone usually begins in which region?
  1. Epiphysis
  2. Articular cartilage
  3. Mid-diaphysis
  4. Metaphysis

Answer: Metaphysis

The metaphysis has looping capillaries draining into large sinusoids with sluggish flow beneath the growth plate, which favours bacterial seeding (most commonly Staphylococcus aureus).

More skeletal system questions

Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.