Gamete Development Differs in Males and Females
Spermatogenesis <ul><li>Spermatogenesis is the production of mature sperm cells. </li></ul><ul><li>Full sperm development ...
 
 
Oogenesis <ul><li>The production of a mature egg characterized by an unequal cytokinesis. </li></ul>
<ul><li>At birth, all primary oocytes for life are present in the body (at least 400,000) </li></ul><ul><li>The primary oo...
 
<ul><li>The cycle continues from puberty until menopause.  </li></ul><ul><li>How many eggs does a woman need? </li></ul><u...
Spermatogenesis and Oogenesis <ul><li>Spermatogenesis </li></ul><ul><li>Involves meiosis </li></ul><ul><li>Produces 4 hapl...
 
When can a woman get pregnant? <ul><li>The egg is viable for 12-24 hours after it has left the ovary (ovulation) </li></ul...
 
 
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Gamete Devloment

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Gamete Devloment

  1. 1. Gamete Development Differs in Males and Females
  2. 2. Spermatogenesis <ul><li>Spermatogenesis is the production of mature sperm cells. </li></ul><ul><li>Full sperm development occurs in the testes and usually takes about two months for full development. </li></ul><ul><li>The male ejaculate contains 100 – 200 million sperm. </li></ul><ul><li>This process begins at puberty and continues until death. </li></ul>
  3. 5. Oogenesis <ul><li>The production of a mature egg characterized by an unequal cytokinesis. </li></ul>
  4. 6. <ul><li>At birth, all primary oocytes for life are present in the body (at least 400,000) </li></ul><ul><li>The primary oocytes are ‘frozen’ before they have the chance to complete meiosis . </li></ul><ul><li>When a girl goes through puberty, hormones are made that stimulate one ‘frozen’ oocyte (at a rate of 1 per month) to continue meiosis. IF a sperm is present, meiosis will be completed and the sperm will fertilize the new egg. </li></ul><ul><li>[Fertilization triggers meiosis to be completed.] </li></ul>
  5. 8. <ul><li>The cycle continues from puberty until menopause. </li></ul><ul><li>How many eggs does a woman need? </li></ul><ul><li>12 per year for how many years… </li></ul><ul><li>35-40 years (at the most) = 420-480 eggs and she starts with 400,000… </li></ul><ul><li>The age of the egg = the age of the woman </li></ul>
  6. 9. Spermatogenesis and Oogenesis <ul><li>Spermatogenesis </li></ul><ul><li>Involves meiosis </li></ul><ul><li>Produces 4 haploid daughter cells </li></ul><ul><li>Each daughter cell develops into a sperm </li></ul><ul><li>Process begins at puberty (sperm are all ‘fresh’) </li></ul><ul><li>Process ends at death </li></ul><ul><li>Billions are produced at a time. </li></ul><ul><li>Oogenesis </li></ul><ul><li>Involves meiosis </li></ul><ul><li>Can produce 4 haploid daughter cells </li></ul><ul><li>One daughter cell becomes the egg; three polar bodies die </li></ul><ul><li>Process begins before birth (eggs are as old as the female) </li></ul><ul><li>Process ends at menopause </li></ul><ul><li>One egg matures monthly. </li></ul>
  7. 11. When can a woman get pregnant? <ul><li>The egg is viable for 12-24 hours after it has left the ovary (ovulation) </li></ul><ul><li>The sperm is viable for up to 72 hours (although most sperm retain their fertilizing power only for 12 to 48 hours after ejaculation.) </li></ul><ul><li>The ‘window of opportunity’ for fertilization – 72 hours prior to ovulation to 24 hours after ovulation. This equates to only 3 to 4 days a month. </li></ul>

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