Early appearance of the secondary vertebral ossification centers.
D000365:Age Determination by Skeleton; D000367:Age Factors; D000886:Anthropometry; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D010012:Osteogenesis; D012737:Sex Factors; D013131:Spine / Q000000981:diagnostic imaging / Q000254:growth & development*