A textbook of obstetrics . n as in the early stages ofdevelopment each placenta,even in unioval twins, isseparate. When the em-bryos are derived each froma separate ovum, thereshould be separate decidualreflexae, chorions, and pla-centae. Occasionally, how-ever, when the ova are im-planted close together, theplacentae may be joined,there may be but onedecidua reflexa, and itmay be difficult to detectthe double layer of chorionthat should separate thetwo ova. Although twins are notinfrequently born, the con-dition should be regarded aspathological in its influence,at least, upon the
A textbook of obstetrics . n as in the early stages ofdevelopment each placenta,even in unioval twins, isseparate. When the em-bryos are derived each froma separate ovum, thereshould be separate decidualreflexae, chorions, and pla-centae. Occasionally, how-ever, when the ova are im-planted close together, theplacentae may be joined,there may be but onedecidua reflexa, and itmay be difficult to detectthe double layer of chorionthat should separate thetwo ova. Although twins are notinfrequently born, the con-dition should be regarded aspathological in its influence,at least, upon the statistics collected bySchatz,2 it appears that intwins from different ova one would be born dead in everytwenty-three cases, while from the same ovum the death-ratewould be one in six. One fetus will, perhaps, outstrip its fellowin growth, and divert the greater part of the nourishment fromthe mother to itself, thus growing rapidly and encroaching soupon the room that should belong to the weaker fetus that the. Fig. ).—Fetus papyraceus(authors specimen). 1 Occasionally two fetuses are found in a single amniotic cavity, which is to beexplained | i) by the atrophy and absorption of the contiguous amniotic walls; (2) byrupture of the amnion in the latter months from the vigorous movements of thefetus; or (3) by the development of but a single amnion from the very beginning(Myschkin, Virchows Archiv, Bd. cviii, S. 133, 146). 2 Archiv f. Gyn., Bd. xxix, S. 438. Till-: FETAL APPENDAGES. <j\ latter is killed and finally pressed flat against the uterine wall(fetus papyraceus). Hydramnios is also very common in twinpregnancies, and occasionally one fetus is converted into anacardiae monster. If the fetuses of a twin pregnancy escapethe dangers of intra-uterine life, there are many complicationsawaiting them in labor. Should one fetus die during pregnane},it is usually retained until term, when the living and dead childrenare cast off together, widely different in appea
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Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
