A manual of obstetrics . -i Fig 23—formation of the polarglobule I, zona pellucida, containingspermatozoa; 2,yelk; 3,4,germinal ves-icle ; 5, the polar globulci 48 A MANUAL OF OBSTETRICS. the polar globules (Fig. 23), take place from the contractedyelk into the clear space beneath the vitelline membrane. Anew nucleus now appears from the debris of the fadedgerminal vesicle, and to it has been given the name of thefemale pronucleus. In the center of the contracted yelk aclear vesicle appears, known as the vitelline nucleus, andthis is regarded as the first sign of impregnation. The changes in t
A manual of obstetrics . -i Fig 23—formation of the polarglobule I, zona pellucida, containingspermatozoa; 2,yelk; 3,4,germinal ves-icle ; 5, the polar globulci 48 A MANUAL OF OBSTETRICS. the polar globules (Fig. 23), take place from the contractedyelk into the clear space beneath the vitelline membrane. Anew nucleus now appears from the debris of the fadedgerminal vesicle, and to it has been given the name of thefemale pronucleus. In the center of the contracted yelk aclear vesicle appears, known as the vitelline nucleus, andthis is regarded as the first sign of impregnation. The changes in the oosperm or blastosphere consist pri-marily in a division of the vitelline nucleus, followed by. Fig. 24.—Formation of the blastodermic membrane from the cells of the muriform body : i,layer of albuminous material sunounding 2, the zom pellucida (after Joulin). segmentation of the vitellus. This process of division andsubdivision proceeds rapidly until the morula, muriformbody, or mulberry mass, as it is variously termed, is the center of this morula there appears an accumu-lation of a transparent fluid, which by its pressure crowdsthe morula, in the form of a thin layer of cell-like struc-tures, against the vitelline membrane. To this cellularlayer has been assigned the name of the blastoderm orblastodermic membrane (Fig. 24), and from it arc developed [J(jlyU*y\^ PREGNAV OR GESTATION. 49 the various fetal portioiW \ The entire ovum at this stage istermed the blastodcruitK vesicle The blastoderm undergoes a rapid series of layer^ may be disfting^ished, the outer of which is the ^iikktSL, the middle tlliypobhift^ Each of these lay^the development of
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectobstetrics, bookyear1
