About Carnegie Stage 21
Most embryos at stage 21 are approximately 52 postovulatory days old and measure 22-24 mm in length. Distinguishing criteria for this stage include swelling of the distal phalanges of the hand to form tactile pads, slight flexure of the wrists with the hands approaching the midline over the cardiac eminence, the feet meet or nearly touch at the midline, the toes are distinct, and the superficial vascular plexus of the head is now more than half the distance from the eye-ear level to the vertex of the head.