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A Human Embryo of Streeter Age Group XIX

서울대학교 의과대학
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A human embryo was obtained incidentally from an operation specimen for uterine leiomyoma. The embryo was 19mm in crown to rump length. It was serially sectioned in 4μm and examined. The embryo was characterized by a thin cornea which ₩a s a layer of loose mesoderm, the optic stalk showing thread-like lumen and ependymal remnant along its whole length, and short up-turning tip of the cochlea. It also showed capillaries appearing in the mesoderm at the rostral surface of anterior lobe of the hypophysis which had a slender stalk from the oral epithelium, the pit-like vomeronasal organ, knob-like branches of the submandibular duct, haphazard orientation of metanephrogenic cells around the tertiary branches of ureter, and clearing centers in the chondrified bones. The embryo was supposed to be male according to the cord-like epithelial proliferation in the medulla of the testis and to the absence of fusion between the two paramesonephric ducts. From the above findings we concluded that this normal embryo belonged to the age group XIX of Streeter’s developmental horizon.

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