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Human Reproduction

Explore the intricate process of how humans produce offspring through gamete formation, fertilization, and embryonic development. Learn about the stages and locations of gamete production in males and females, the fertilization process, and what happens after successful fertilization. Find out when gametes are produced and how they come together to create new life.

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Human Reproduction

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  1. Human Reproduction How do we produce offspring?

  2. What has to happen… • Each parent-to-be must produce gametes • The gametes have to be able to get together • The fertilized egg has to have a place to develop • The baby must be provided nourishment during fetal development period • The baby has to have a way to be delivered • The baby must be provided nourishment following birth

  3. How do we produce gametes? • Gametes: haploid sexual reproductive cells—eggs, sperm • Produced through meiosis cell divisions • 2 consecutive cell divisions which take chromosomal count from diploid (2n = 46) to haploid (n =23) • Meiosis • http://www.cellsalive.com/meiosis.htm

  4. Gametogenesis • Spermatogenesis http://www.soc.ucsb.edu/sexinfo/images/12-06-spermatogenesis.gif http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookREPROD.html • Oogenesis • http://www.tarleton.edu/~anatomy/oogenesis.html

  5. Where does gamete formation occur? Male • In testes in scrotal sacs (lowers T) • Meiosis occurs continuously in seminiferous tubules • Sperm stored in epididymis • 100,000,000 sperm per day! http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookREPROD.html http://en.wikibooks.org/wiki/Human_Physiology/The_male_reproductive_system

  6. Where does gamete formation occur? Female • In ovaries • Born with ~500,000 eggs • One egg matured per month, once puberty has been reached • Continues until menopause • http://en.wikipedia.org/wiki/Ovary

  7. When are gametes produced? Male • Continuously once puberty reached • 400 billion + in lifetime • Under control of hormones, particularly LH and testosterone Female • Monthly cycle • http://www.sumanasinc.com/webcontent/animations/content/ovarianuterine.html • http://www.embryology.ch/anglais/cgametogen/oogenese04.html

  8. Getting gametes together:fertilization Where • Outer third of fallopian tubes (oviducts) http://http://catalog.nucleusinc.com/enlargeexhibit.php?ID=4631 • http://health.howstuffworks.com/adam-200112.htm When • Within 12-18 hours of release of mature egg • If not fertilized, it degenerates and is discarded • Sperm can wait up to 5-6 days for egg (either side of ovulation) • 200-300million sperm per ejaculation (20% defective, 25% die immediately)

  9. Success! (if planned)! Egg fertilized …now what? • Undergoes repeated mitotic divisions to form blastocyst • Must reach this stage when entering uterus to be able to implant in uterine wall • http://www.biology.iupui.edu/biocourses/n100/2k4ch39repronotes.html • http://embryo.soad.umich.edu/carnStages/carnStages.htmlhttp://embryology.med.unsw.edu.au/

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