The practice of obstetrics, designed for the use of students and practitioners of medicine . Fig. 56.—Segmentation of the Ovum, Rab-bit. Many-celled or Morula spermatozoa lie in the thick-ened egg membrane.—{After Bischoff.) Segmentation.—In the human ovum nothing is known of the process bywhich a single cell subdivides into many. In lower vertebrates and severalmammals the process has been carefully followed. In the latter, the segmenta-tion-nucleus divides, thus forming two cells which again divide. These four againdivide, and the process of subdivision is continued until a so
The practice of obstetrics, designed for the use of students and practitioners of medicine . Fig. 56.—Segmentation of the Ovum, Rab-bit. Many-celled or Morula spermatozoa lie in the thick-ened egg membrane.—{After Bischoff.) Segmentation.—In the human ovum nothing is known of the process bywhich a single cell subdivides into many. In lower vertebrates and severalmammals the process has been carefully followed. In the latter, the segmenta-tion-nucleus divides, thus forming two cells which again divide. These four againdivide, and the process of subdivision is continued until a soHd ball of cells is4 50 PHYSIOLOGICAL PREGNANCY. formed, the early blastula or morula, so called rom its resemblance to a mulberry(Figs. 54, 55, and 56). In Amphioxus and some other lower forms the morula. Fig. 57.—Segmentation of the Ovum. Sections of the Ovum of the Rabbit DuringTHE Later Stages of Segmentation, showing the Formation of the BlastodermicVesicle, a, Showing the outer layer and the inner cell mass before the formation of acavity; also the so-called blastopore *; b, showing the cavity formed by the absorptionof liquid; c, enlarged cavity; d, showing the cell mass forming a layer at one side of thethinned outer or Raubers layer; ent., inner mass of cells; ect., outer or subzonal the ovum attaches itself to the uterine wall, this laj^er becomes the trophoblast;, zona pellucida.—{After van Beneden.)
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectobstetrics, bookyear1
