A system of obstetrics . c. The epiblasticspheres have now become markedly smaller than the hypoblastic(Fig. 15, d). The four hypoblastic sphere- next divide, giving rise, together withthe eight epiblastic spheres, to sixteen cells in all, which are aearlyuniform in size. Of the eight [hypoblastic] spheres, four soon pa— tothe centre, while the eight superficial [epiblastic] spheres form a kindof enp partially enclosing the [hypoblastic] spheres (Fig. 15, e). The[epiblastic] spheres now divide in their turn, giving rise t -ixteenspheres, which largely enclose the [hypoblastic] spheres. The seg
A system of obstetrics . c. The epiblasticspheres have now become markedly smaller than the hypoblastic(Fig. 15, d). The four hypoblastic sphere- next divide, giving rise, together withthe eight epiblastic spheres, to sixteen cells in all, which are aearlyuniform in size. Of the eight [hypoblastic] spheres, four soon pa— tothe centre, while the eight superficial [epiblastic] spheres form a kindof enp partially enclosing the [hypoblastic] spheres (Fig. 15, e). The[epiblastic] spheres now divide in their turn, giving rise t -ixteenspheres, which largely enclose the [hypoblastic] spheres. The segmen-tation of both [epiblastic and hypoblastic cells] continues; in thecourse of it the epiblastic sphere- spread farther and farther over thehypoblast, so that at the close of segmentation the hypoblast spheresconstitute a central solid mass almost entirely surrounded by the epi-blast spheres. In a small circular area, however, the hypoblast spheresremain for some time exposed on the surface (Fig- 16, A, lyp).. Optiml Sections of an Oosperm of a Rabbit, at two stages closely following upon segmentation(from Balfour,after Ed. v. Beneden): ep, epiblast; hy, primary hypoblast; bp, the openingin the epiblastic layer at one point, named blastopore by E. van Beneden: this Is not a trueblastopore. The Bhading ( the epiblasl and hypoblast i- diagrammatic. The whole process of segmentation is completed in the rabbitaboul seventy hours after impregnation. At its close the c]>i/>fl)l<isf alls are polygonal and granular, and some-what larger than the epiblast cells. THE EARLY STAGES OF DEVELOPMENT. 10:5 [The developing oosperm at the close of segmentation is named themorula or mulberry mass.] After its segmentation the [oosperm] passes into the uterus. Theepiblast cells soon grow over the blastopore [of Van Beneden, which ismerely an uncovered part of the hypoblast], (6p, Fig. 16,
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectobstetrics, bookyear1
