vocabulary

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Across
  1. 4. that closely covers the human and various other embryos when first formed
  2. 5. cluster of dividing cells made by a fertilized egg of
  3. 6. the origin and development of the sperm cells within the male reproductive organs, the testes
  4. 8. the middle of the three primary germ layers of an embryo that is the source of many bodily tissues and structures
  5. 10. a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes
  6. 13. cells forming the outer layer of a blastocyst, which provides nutrients to the embryo, and develops into a large part of the placentaorgan that connects the developing fetus to the uterine wall, thereby allowing nutrient uptake, waste elimination, and gas exchange via the mother's blood supply
  7. 14. a series of mitotic divisions whereby the enormous volume of egg cytoplasm is divided into numerous smaller, nucleated cells.
  8. 16. a reproductive cell of an animal or plant.
  9. 17. the outermost of the three primary germ layers of an embryo that is the source of various tissues and structures
  10. 18. an organ that develops in the uterus during pregnancy.
  11. 19. a critical process during week 3 of human development
  12. 20. a small membranous structure outside the embryo with various functions during embryonic development.
  13. 21. early multicellular embryo, composed of two or more germinal layers of cells from which the various organs later derive
  14. 22. a thin membrane forming a closed sac about the embryos or fetuses of reptiles, birds, and mammals and containing the amniotic fluid
Down
  1. 1. the process by which the female gametes, or ova, are created
  2. 2. the innermost of the three basic layers of an embryo that forms the epithelium of the digestive tract and the parts of the body formed from it.
  3. 3. the production of gametes from haploid precursor cells
  4. 7. an extra-embryonic membrane of reptiles, birds, and mammals arising as a pouch, or sac, from the hindgut.
  5. 9. fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm)
  6. 11. consist of the chorion (the combination of trophoblast plus underlying extraembryonic mesoderm), amnion, yolk sac, and allantois
  7. 12. hollow sphere of cells, or blastomeres, produced during the development of an embryo by repeated cleavage of a fertilized egg
  8. 15. the union of two gametes