Carnegie Stage 18 Definition

Age is approximately 44 postovulatory days

Length is approximately 13-17 mm

External Features Include: the body is more of a unified cuboidal mass, both cervical and lumbar flexures are indicated; the digital plate of the hand is definitely notched, the elbow region is usually discernable, toe rays can be identified in some specimens; eyelid folds are present in the more advanced specimens; a distinct tip of the nose can be seen in profile.


(O'Rahilly R and Muller F [1987] Developmental Stages in Human Embryos. Carnegie Institute, Washington, Publication no. 637)