Learn about Implantation of the Ovum in this educational video from dizzo95.
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Male Speaker: Within a few hours of fusion of the sperm and the ovum cell division begins the number of cells double with each successive division unto a hallow bowl of rapidly dividing cells is produced throughout the process the ovum is moving down the fallopian tube toward the uterus. 5-6 days after the fusion the ovum reaches the uterus and implants itself in the soft wall. The hallow ball of the cells now contains up to 100 cells arranged as an outer ring and an inner mask. The outer ring grows upward and penetrates to uterine tissue while the inner mask divides into two separate layers an inner endoderm and an outer ectoderm, these two layers become separated from the outer ring and by 9 days form two cavities within the hallow bowl. The ectoderm later spreads around the periphery of the smaller cavity forming a sac, the amnion which was surround and protect the developing embryo. The endoderm similarly encloses the larger cavity to form a yoke sac which will have a nutritive function.