The development of the human body; a manual of human embryology . ON Fig. 67.—Two Villi from the Chorion op an Embryo op 7 mm. These villi may at first be developed over the wholesurface of the chorion or they may be limited to a broadband situated at what may be termed the equator of theovum; but whichever arrangement occurs, only those de-veloped from that portion of the chorion to which thebelly-stalk is attached undergo further elaboration inlater stages, the rest gradually disappearing or remainingonly as minute rudiments. It is customary, consequently, 144 THE DEVELOPMENT OF THE HUMAN BO
The development of the human body; a manual of human embryology . ON Fig. 67.—Two Villi from the Chorion op an Embryo op 7 mm. These villi may at first be developed over the wholesurface of the chorion or they may be limited to a broadband situated at what may be termed the equator of theovum; but whichever arrangement occurs, only those de-veloped from that portion of the chorion to which thebelly-stalk is attached undergo further elaboration inlater stages, the rest gradually disappearing or remainingonly as minute rudiments. It is customary, consequently, 144 THE DEVELOPMENT OF THE HUMAN Fig. 68.—Transverse Sections through Chorionic Villi in (A) the Fifth and (B) the Seventh Month of Development. cj, Canalized fibrin; Ic, Langhans cells; s, syncytium.—(A, which is more highly magnified than B, from Szymonowicz; B from Minot.) THE CHORION. 145 to speak of that portion of the chorion in which the de-velopment of the villi proceeds as the chorion frondosum, todistinguish it from the remaining portion, which is termedthe chorion Iceve. The villi (Fig. 67) at first are irregularly lobed processesformed by a solid mass of trophoblast cells and projectingfully into the intervillous space, a lobe here and thereextending completely across the space (Fig. 76) and unit-ing with the maternal tissues to form roots of development proceeds the lobes become much moreslender and branch so that each villus assumes a dendriticform. In the mean time, however, processes from thechorionic mesoderm grow out into each villus, extendingout even into the terminal branches an
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
