Clinical_Rounds_in_Endocrinology_Volume_II_-_Pediatric_Endocrinology

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GH

IGF- 1

GC

T3

Pro-proliferative

Pro-proliferative

Growth arrest, inhibits

hypertrophic

differentiation

Antiproliferative,

promotes

hypertrophic

differentiation

Epiphysis

Vascular

invasion

Bone

Trabeculae

RZ

PZ

HZ

CZ

GH

T3

IGF-1

GC

T3

GH

IGF-1

GC

T3

GS

IGF-1

GH

GC

RZ - Resting zone

PZ - Proliferative zone

HZ - Hypertrophic zone

CZ - Calcification zone

GS - Gonadal steroids

GC - Glucocorticoids

EPIPHYSIS

METAPHYSIS

Resting Zone

Proliferative Zone

Hypertrophic Zone

a

b

Fig. 1.3 (a) Different zones of growth plate. (b) Site of action of various endocrine and paracrine
factors on growth plate

These terminally differentiated cells eventually undergo apoptosis. Later, the

growth plate is invaded by blood vessels and bone cell precursors from metaph-

ysis, resulting in remodeling of cartilage into bone, a process termed as endo-

chondral ossification. The various endocrine and paracrine factors that regulate

“chondro- osteogenesis” are depicted in the figure given below (Fig. 1.3).

1 Disorders of Growth and Development: Clinical Perspectives