The development of the human body; a manual of human embryology . hich, as willbe seen in a subsequent chapter, takes place only at alater stage of development. From now on the tropho-blast and the layer of mesoderm lining it may together bespoken of as the chorion, the mesoderm layer being termedthe chorionic mesoderm. A human embryo of a somewhat greater age (Fig. 37),measuring about mm. in length, has been describedby Graf Spee as embryo , and was taken from anovum estimated to measure 6 by mm. in the much greater size of the ovum, THE EXTERNAL FORM OF
The development of the human body; a manual of human embryology . hich, as willbe seen in a subsequent chapter, takes place only at alater stage of development. From now on the tropho-blast and the layer of mesoderm lining it may together bespoken of as the chorion, the mesoderm layer being termedthe chorionic mesoderm. A human embryo of a somewhat greater age (Fig. 37),measuring about mm. in length, has been describedby Graf Spee as embryo , and was taken from anovum estimated to measure 6 by mm. in the much greater size of the ovum, THE EXTERNAL FORM OF THE BODY. 85 which is due to the continued increase in the size of theextra-embryonic ccelom, the embryo is but little advancedbeyond the stage which the Peters embryo had reached,and is probably in a late stage of the development of theprimitive streak. Confining the attention for the presentsolely to the embryo and the immediately adjoining parts,it will be seen that the thickening of the chorionic meso-derm which encloses the amniotic cavity has increased in. Fig. 37.—Ovum Measuring 6 >( mm. The Left Half ofthe Chorion has Been Re-moved to show the Embryo. a, Amniotic cavity; 6, belly-stalk;c, chorion; e, embryonic disk; v,chorionic villus; y, yolk-sac.—(von Spec.)
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
