Embryo of the American Alligator Alligator mississippiensis at 33 days of development (approximately 50% of the entire embryonic period). All of the external structures, including characteristic jaws and limbs, are already in place and clearly visible.

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Embryo of the American Alligator Alligator mississippiensis at 33 days of development (approximately 50% of the entire embryonic period). All of the external structures, including characteristic jaws and limbs, are already in place and clearly visible. . Arkhat Abzhanov, Imperial College London. Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Source: Wellcome Collection.