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Starter. Describe the function of each of the following parts. Testis Vas deferens Epididymis Seminal vesicle. Starter. Testis: sperm production / testosterone production. Vas deferens: carry sperm from testis / epididymis to urethra / penis.

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Starter

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  1. Starter • Describe the function of each of the following parts. • Testis • Vas deferens • Epididymis • Seminal vesicle

  2. Starter • Testis: sperm production / testosterone production. • Vas deferens: carry sperm from testis / epididymis to urethra / penis. • Epididymis: sperm mature here/sperm stored here. • Seminalvesicle: addsugarto sperm.

  3. Starter • The diagram shows a section through an ovary. • Name and describe the process that has occurred at A.

  4. Starter • The diagram shows a section through an ovary. • Name the hormone the corpus luteumproduces. • Describe the function of this hormone.

  5. Starter • Explain why the testes need to be outside the body to make healthy sperm. • Explain why a man must have a high sperm count if his partner is to become pregnant.

  6. Implantation Embryo Development

  7. Embryo Development • After fertilization the zygote begins to divide by mitosis, first into 2 cells, then 4, then 8, etc. • Eventually a solid ball of cells, called a morula, is formed.

  8. Embryo Development • By the time the ball of cells reaches the uterus it has developed a fluid filled cavity and is called a blastula.

  9. Embryo Development

  10. Blastocyst

  11. Developing oocyte surrounded by follicle.

  12. Released ovum with polar body.

  13. Fusion of the sperm and ovum nucleus.

  14. Mitotic division of the zygote.

  15. Implantation • Implantation is the event where the blastocyst becomes buried in the lining of uterus. • The blastocyst develops villi to increase the surface area for food absorption.

  16. Implantation • Eventually these villi become concentrated in one area (early placenta).

  17. The Placenta • The placenta is a temporary organ that develops partly from the mother and partly from the embryo.

  18. The Placenta • The placenta has two main functions: • It facilitates the transfer of substances (nutrients and wastes) between the mother and the embryo.

  19. The Placenta • Early on the corpus luteum keeps producing oestrogen and progesterone. • Eventually the corpus luteum dies and it is the placenta that takes over production of these hormones that are essential in maintaining pregnancy.

  20. The Placenta • The blood of the mother and embryo come close but never mix. • Mixing of blood could allow for the transfer of pathogens. • The mother and baby could have different blood types.

  21. Villi Wall Capillary Wall Maternal Blood Foetal Blood Carbon Dioxide Oxygen Amino Acids Urea Glucose

  22. The Placenta • The embryo is very delicate and requires protection from potential impact. • The amnion is a membranous sac which surrounds and protects the embryo. • Within the amnion is about 1 litre of amniotic fluid that acts to cushion the embryo and allow it to move freely in the uterus.

  23. Placenta

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