1 / 11

Gamete Maturation

Gamete Maturation. Chapter 3: Meiosis & Development 3.3: Gamete Maturation. How do sperm form?. Spermatogenesis- formation of sperm cells Begins in testes with diploid stem cells called spermatogonia

zachery-cruz
Download Presentation

Gamete Maturation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Gamete Maturation Chapter 3: Meiosis & Development 3.3: Gamete Maturation

  2. How do sperm form? • Spermatogenesis- formation of sperm cells • Begins in testes with diploid stem cells called spermatogonia • Spermatogonia will divide into two daughter cells, one will stay in the stem cell niche and the other will begin process of spermatogenesis

  3. How do sperm form? • Spermatogonium accumulates cytoplasm & replicates DNA • Becomes diploid primary spermatocyte • Primary spermatocyte undergoes meiosis I and forms 2 equal sized haploid secondary spermatocytes

  4. How do sperm form? • Secondary spermatocytes undergo meiosis II and divide to form 4 equal sized haploid spermatids. • Spermatids will grow flagellum and become spermatozoa a.k.a. sperm cells

  5. What are the anatomical structures of a sperm? 3 Body Regions • Head- • Nucleus- holds DNA (23 chromosomes) • Acrosome- cap at the front end of sperm that holds enzymes that will be used to penetrate the egg. • Midpiece- has spiral mitochondria which provides energy for swimming • Tail- flagellum for movement

  6. How do eggs form? • Oogenesis- formation of egg cells • Begins in ovary with diploid stem cells called Oogonia • Each oogonium is surrounded by a follicle cell • A woman is born with all oogonia she is ever going to have.

  7. How do eggs form? • Oogoniumaccumulates cytoplasm & replicates DNA • Becomes diploid primary oocyte • Primary oocyte undergoes meiosis I and forms 2 unequal sized haploid cells: • First Polar Body- small cell with very little cytoplasm • Secondary oocyte- larger cell that will go on to meiosis II

  8. How do eggs form? • First Polar Body can have 2 fates: • Decompose & die • Divide & become second polar bodies which will be absorbed by body • Secondary oocyte divides unequally again in meiosis II and forms: • Second polar body- small cell with little cytoplasm that is absorbed by body • Ovum- egg cell with large volume of cytoplasm • This happens once a month after puberty starts

  9. What happens if a sperm fertilizes a polar body? • Very rare • Body responds as if pregnant • Cell division is unorganized- not considered an embryo • Body causes miscarriage called “blighted ovum”

  10. In females: In ovaries Produces: 1 mature egg, 3 polar bodies which break down Women born with all eggs they will have. Egg is much larger Have all X chromosomes Has no method of movement In males: In testes Produces:4 mature sperm Males begin to produce sperm after puberty, produced constantly until death Much smaller than egg May have X or Y chromosomes Have flagella to move Summary of gametogenesis in males vs. females

More Related