Quain's elements of anatomy . cubatedegg, fiom the effect of change of temperature or other stimuli, activemotions may be perceived, caused by the alternate contraction and re-laxation of different parts of the membrane. In some of the mammalia the origin and early development of theallantois is nearly the same as in birds, but in a more advanced stage ofdevelopment the relations of this membrane to the other parts of theovum are greatly modified hj its combination with the chorion, moreespecially in the region of the placenta. In most mammalis the external or mesoblastic lamina of the allanto
Quain's elements of anatomy . cubatedegg, fiom the effect of change of temperature or other stimuli, activemotions may be perceived, caused by the alternate contraction and re-laxation of different parts of the membrane. In some of the mammalia the origin and early development of theallantois is nearly the same as in birds, but in a more advanced stage ofdevelopment the relations of this membrane to the other parts of theovum are greatly modified hj its combination with the chorion, moreespecially in the region of the placenta. In most mammalis the external or mesoblastic lamina of the allantoisimdergoes greater extension than the inner hy[3oblastic_sac, and this isremarkably the case in the human subject, in which it is still doubtfulwhether any internal vesicle is present beyond the lunits of the umbilicalcord. In the hmnan ovmn the external or mesoblastic vascular elementprobably spreads at a very early period over the whole interior of thechorion (placental and non-placental parts), while the internal or hypo-. MEMBEANES OF THE OVUM. 769 blastic vesicle either shrinks and atrophies at a very early period or iscomparatively small and has never reached the interior of the subject will again be referred to in the account of hmnan utero- gestation. Fig. 662,
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
