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Stage 19 embryos have a greatest length of 16 to 18 mm and an estimated postfertilization age of approximately 45 to 47 days. The trunk is elongating and straightening. The head no longer forms a right angle with the back and is beginning to elevate. The hand and footplates contain distinct metacarpal and metatarsal condensations, respectively. The auricular hillocks are no longer evident and have blended forming definitive parts of the external ear. The cochlear duct begins its 2½ turn spiral with the tip turned upward.


New structures include abducens nucleus, cerebral aqueduct, middle cerebral artery, parotid gland bud, renal artery, tibia.

Section 366

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There are no published figures for this stage.