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Atlas of Human Embryos Chapter   Figure

S-3 somite, T-4 dermatome, T-4-T-5 intercrest region, T-5 dermatome, amnion, cloaca, cloacal membrane, common umbilical artery separating into right and left branches, common umbilical vein, hindgut, junction of allantois with urogenital sinus, left umbilical vein, neural tube, notochord, postcardinal vein, right umbilical vein, sclerotome, umbilical cord, urogenital mesentery

A section through the T-4–T-5 intercrest region and the cloacal membrane at the level of the S-3 somite.

Observe:
1. The separation of the umbilical cord from the ventral body wall and the attachment of the amnion.
2. The large vessels in the umbilical cord and the common umbilical artery separating into right and left branches.
3. The S-3 somite and its relation to the neural tube.
4. The cloacal membrane that is composed of ectoderm and endoderm and separates the cloaca from the exterior.
5. The junction of the allantois with the urogenital sinus.


Keywords: S-3 somite, T-4 dermatome, T-4-T-5 intercrest region, T-5 dermatome, amnion, cloaca, cloacal membrane, common umbilical artery separating into right and left branches, common umbilical vein, hindgut, junction of allantois with urogenital sinus, left umbilical vein, neural tube, notochord, postcardinal vein, right umbilical vein, sclerotome, umbilical cord, urogenital mesentery

Source: Atlas of Human Embryos.