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Reproduction in Lower and Higher Animals — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYReproduction in Lower and Higher Animals5 Marks
Question
Implantation
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Answer

  1. Implantation is the process by which the blastocyst is embedded into the endometrium of uterus in the fundus region.
  2. The implantation starts 7 days after fertilization and completed by the end of 10th day.
  3. The trophoblast cells of blastocyst at the embryonal knob can stick to the uterine endometrium. The trophoblast layer then divides into inner cytotrophoblast and outer syncytiotrophoblast due to contact with endometrial cells.
  4. Cytotrophoblast is the inner layer whose cells retain their cell boundaries.
  5. Syncytiotrophoblast is the outer layer of cells without plasma membrane. The cells of syncytiotrophoblast appear multinucleate. This layer projects invasively into the endometrium and destroys endometrial cells by releasing lytic enzymes. Due to this blastocyst is buried deeply in the endometrium.

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