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Genitourinary System

Genitourinary System . Part 2. Spermatogenesis. The production of spermatozoa Produced in the testis:. Seminiferous Tubules Micrograph. Stages of Spermatogenesis. Oogenesis – the production of an ovum. Ovary cross sectional micrograph. Stages of Oogenesis. Gametes.

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Genitourinary System

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  1. Genitourinary System Part 2

  2. Spermatogenesis • The production of spermatozoa • Produced in the testis:

  3. Seminiferous Tubules Micrograph

  4. Stages of Spermatogenesis

  5. Oogenesis – the production of an ovum

  6. Ovary cross sectional micrograph

  7. Stages of Oogenesis

  8. Gametes • Human Sperm – structure

  9. Hormonal Control of Spermatogenesis

  10. Semen Production • 3 main structures play a role • Epididymis – storage/holding area where sperm mature and become fully motile • Seminal vesicle and prostate gland – produce, store and expel fluid during ejaculation • Fluid mixes with sperm to increase volume of ejaculate; s.v. fluid contains nutrients (including fructose) and mucus (protection); • Fluid from p.g. contains mineral ions, and is alkaline (protection)

  11. Human Egg – structure: (n) nucleus; corona radiata; cortical granules; diameter 100um (1/10th mm)

  12. Guys Millions daily Released during ejaculation Starts during puberty Production continues throughout adult life Four functional gametes per meiosis Girls 1/28 days Released via ovulation Starts prenatally Stops at menopause 1 functional gamete per meiosis Spermatogenesis vs. oogenesis

  13. Fertilization

  14. Stages of Fertilization

  15. Stages of Early embryological Development

  16. Development of the Fetus

  17. Development of Fetus cont’d • By 8 weeks of development, bone and tissue start to develop, embryo now referred to as a fetus. • Placenta and umbilical cord develop

  18. Development of Fetus: Placenta cont’d • Site of nutrient and gas exchange • No mixing of maternal and fetal blood

  19. Amniotic Sac and Fluid • Support and protection • Basis for amniocentesis

  20. Hormonal Control of Pregnancy • Estrogen and progesterone – needed to stimulate the development of uterine lining throughout pregnancy. • Secreted by corpus luteum (c.l.) for first week following fertilization • Following implantation embryo secretes HCG = prevents degeneration of c.l. = continued secretion of est. and progest. • C.l. degenerates middle of term, placental cells now produce est. and progest. Until end of pregnancy

  21. Childbirth

  22. Childbirth cont’d • End of pregnancy signalled by fall in progesterone level • Oxytocin begins being secreted = stimulates smooth muscle (uterus) contraction • Positive feedback loop

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