Carnegie Stages of Human Embryonic Development

Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo. Only the 60 days of a baby’s embryonic development are covered prior to them entering into their fetal stage of development.

Carnegie Stage 1 [1 Day – Two Unfused Pronuclei]

Carnegie Stage 2 [2-3 Days – Two-Cell Segmenting Egg]

Carnegie Stage 2 [2-3 Days – Mid-Serial Section Two-Cell]

Carnegie Stage 2 [2-3 Days – Two Mitotic Cell Divisions and Four Blastomeres]

Carnegie Stage 2 [2-3 Days – Early Morula Stage]

Carnegie Stage 3 [4-5 Days – Large Blastocoel]

Carnegie Stage 3 [4-5 Days – Blastocyst Hatching]

Carnegie Stage 4 [5-6 Days – Embryo Attached to Endometrium]

Carnegie Stage 5 [7-12 Days – Implantation Site]

Carnegie Stage 6 [13-16 Days – Gastrulation]

Carnegie Stage 7 [15-17 Days – Embryonic Disc]

Carnegie Stage 8 [17-19 Days – Neural Groove]

Carnegie Stage 9 [19-21 Days – Neural Folds]

Carnegie Stage 10 [22-23 Days – Neural Tube]

Carnegie Stage 11 [23-26 Days – Rostral Neuropore Closes]

Carnegie Stage 12 [26-30 Days – Forebrain]

Carnegie Stage 13 [28-32 Days – Leg Buds]

Carnegie Stage 14 [31-35 Days – Optic Cup]

Carnegie Stage 15 [35-38 Days – Hand Plate]

Carnegie Stage 16 [37-42 Days – Foot Plate]

Carnegie Stage 17 [42-44 Days – Finger Rays]

Carnegie Stage 18 [44-48 Days – Ossification Commences]

Carnegie Stage 19 [48-51 Days – Straightening of Trunk]

Carnegie Stage 20 [51-53 Days – Upper Limbs Bent at Elbow]

Carnegie Stage 21 [53-54 Days – Hands and Feet Turned Inward]

Carnegie Stage 22 [54-56 Days – Eyelids and External Ears]

Carnegie Stage 23 [56-60 Days – Rounded Head, Body and Limbs]

Embrace the humanity of these little ones in full motion…