Fig. 4

Safranin-Weigert staining of Hox mutant limbs. Arrowhead: radius, Arrow: ulna. a–d, E14.5. a: Wild type, note resting chondrocytes near ends, the proliferative zone more medial, and the hypertrophic compartment, with white spaces. b: Hoxa9,10,11 ^−/−;Hoxd9,10,11 ^+/−, shorter and thicker radius and ulna. c: Hoxa9,10,11 ^+/−;Hoxd9,10,11 ^−/−, shorter and thicker radius and ulna. d: Hoxa9,10,11 ^−/−;Hoxd9,10,11 ^−/−, nearly absent radius and ulna, with only resting chondrocyte morphology. e and f, E15.5. e: Hoxa9,10,11 ^−/−;Hoxd9,10,11 ^+/−, cells present in outgrowth of radius are rotated 90° (insert). f: Hoxd9,10,11 ^+/-, normal cell orientation and differentiation compartments (insert)