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Fig. 2 | EvoDevo

Fig. 2

From: Identifying the homology of the short human pisiform and its lost ossification center

Fig. 2

Progression of mouse pisiform ossification. a Histological section of early stages (P4) of primary ossification. Note the hypertrophic chondrocytes (arrowhead) at the center of the cartilage model. b At P6, primary ossification (arrowhead) expands towards the dorsal end where an articular surface (*) with the ulnar styloid process (U*) and triquetral (Tq) has formed. The growth plate is forming at the palmar end (top). c At P11, primary ossification has completed at the dorsal end and is filled with trabecular bone (arrowhead). Early stages of epiphysis formation are present (arrow). d At P11, the individual reserve (R), proliferative (P), and hypertrophic (H) zones and following ossification front (O) can be identified. The bone collar with adjacent perichondrial ring flanking the growth plate is identified (arrowhead). A subchondral surface is located at the boundary of hypertrophic chondrocytes and the ossification front. e At P23, the pisiform epiphysis is ossified (arrow). f Medial view of a 1 month mouse wrist visualized by microCT. The pisiform (P), ulnar styloid process (U*) and triquetral (Tq) are indicated. The ossified pisiform epiphysis remains unfused at 1 month (arrow). g Slice through 1-month-old mouse pisiform shows the ossified epiphysis (arrow) and subchondral surface of primary ossification (arrowhead). In all panels, palmar is up, dorsal is down, proximal is left, and distal is right. Scale bars = 100 μm

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