Development of the lizard limb as shown by the distribution of [35S]sulphate incorporation.

In the forelimb of the lizard, Chalcides ocellatus (Forskal), the chondrogenic pattern is laid down in a proximodistal direction commencing with the proximal regions. The chondrogenic skeletal pattern along the antero-posterior axis gives humerus, radius, ulna and the distal region. The radius and ulna differ in their length and level of sulphation. The end result is a periodic pattern resembling that in other amniotes. The peripheral areas and distal region show an almost uniform uptake of [35S]sulphate, the basement membrane taking up [35S]sulphate at a higher rate between embryonic stages with limb lengths 0.2 mm and 0.75 mm.