File:A text-book on physiology - for the use of schools and colleges - being an abridgment of the author's larger work on human physiology (1866) (14768249685).jpg

Identifier: textbookonphysio00drap (find matches)
Title: A text-book on physiology : for the use of schools and colleges : being an abridgment of the author's larger work on human physiology
Year: 1866 (1860s)
Authors: Draper, John William, 1811-1882
Subjects: Human physiology Physiology
Publisher: New York : Harper & Bros.
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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place,enhanced by the presence of theovum in the organ, at once in-creases its vascularity; the folliclesbecome larger, cells are abundantlydeveloped in them, and the uterinecavity is filled with a liquid con-taining many nucleated cells. Thisplastic semi-fluid material receivesthe fringes of the villous coat ofthe chorion, now being developed;and these even find their way intothe mouths of the glandular tubes;from this exudation or secretion themembrana decidua forms, thoughby some it is represented as beinga metamorphosis of the mucousmembrane itself. Meantime the ovum is coated overwith a corresponding membrane, designated membranareflexa, because it was believed to originate in the cir-cumstance that, when the ovum reached the uterinemonth of the Fallopian tube, it there encountered theproper membrana decidua, and, not perforating it, butbearing it onward, gathered a fold, covering, or envelope. What does Fig. 136 illustrate ? In what manner does the decidu-ous membrane form ? P2
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Uterine tubes. 346 MEMBRANA DECIDUA AND PLACENTA. It is, however, now admitted that this description of theformation of the membrana reflexa is erroneous, for inreality the ovum is at no time on the outside of the mu-cous membrane, which is continuous from the cavity ofthe uterus through the Fallopian tube. The following,therefore, seems to be the more correct description. Thepresence of the ovum gives rise to an increased develop-ment of cells, rapidly spreading around it, and coating itall over, their points of origin being those portions of theuterine mucous membrane with which the ovum is incontact. In this way it receives its deciduous envelope,which, participating duly in its growth, is at the end of thethird month in contact with the uterine deciduaall over. At the stage we are now considering, the nutrition ofthe embryo is conducted in a special but very temporaryway. The yolk of the ovum has no stock of food tomaintain the nutritive processes beyond the brief spacetranspiring

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