1 / 13

Fertilization

Fertilization. Growth and maturation of oocyte. Growth of the oocyte Essential for successful fertilization and embryonic development Before the ovulation. Immature oocyte surrounded by cumulus cells. Oocyte. Blastocyst stage embryo. Oocyte growth. Primordial. Primary. Secondary.

media
Download Presentation

Fertilization

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. Fertilization

  2. Growth and maturation of oocyte • Growth of the oocyte • Essential for successful fertilization and embryonic development • Before the ovulation Immature oocyte surrounded by cumulus cells Oocyte Blastocyst stage embryo

  3. Oocyte growth Primordial Primary Secondary Antral Growth and maturation of oocyte • Growth of oocytes • Primordial follicles • Commitment for development and differentiation Oocyte Cumulus cells Cumulus-oocyte complex

  4. Oocyte growth Primordial Primary Secondary Antral Growth and maturation of oocyte • Specialized granulosa cells that surround the oocyte • Cumulus cells • Assist growth of the oocyte • Produce growth factors and hormones that are essential for normal oocyte growth and development • Combined structure of the oocyte and cumulus cells • Cumulus-oocyte complex (COC) Oocyte Cumulus cells Cumulus-oocyte complex

  5. Growth and maturation of oocyte • The oocyte increases its size and volume during its growth phase • No mitosis • The maximal number of oocytes present on the ovaries • Set before birth • numbers decrease throughout fetal and adult life • Undergo meiosis • ultimately results in reduction of number of chromosomes by half (46 to 23) • Haploid cells

  6. Growth and maturation of oocyte • Process of meiosis • Begins before primordial follicles are formed • Arrested during oocyte growth • Growth of the oocyte • Almost completed by the time the follicle reaches the antral stage • Meiosis • Arrested until LH surge • Granulosa cells produce factors that inhibit premature resumption of meiosis

  7. Growth and maturation of oocyte • Oocyte after LH surge • Formation of a polar body • a small, round structure in the space between the cytoplasm (inside of the cell) and the clear outer membrane of the oocyte (zona pellucida) • Contains a portion of maternal chromosomes • Expelled as a part of meiosis in order to reduce number of chromosomes present in the oocyte Oocyte Zona pellucida Polar body

  8. Growth and maturation of oocyte • Resumption of meiosis • Changes in the function of cumulus cells • Loss of contact with each other and with the granulosa cells, • Essential for the oocyte to be released from the preovulatory follicle • Production of “sticky” mucus • Necessary for the COC to be picked up by fimbriae after being released from the preovulatory follicle

  9. Release of the oocyte • The COC • Expelled to the outer surface of the ovary after the ovulatory follicle ruptures • Covered with “sticky” mucus • Remains on the site of ovulation unless being picked up by the fimbriae of the oviduct

  10. Oocyte in the oviduct Ovary Infundibulum • The pickup of COC • The structural design of the fimbriae • Close proximity of the ovary to the oviduct • Coordinated contraction of ligaments surrounding the ovaries and uterus Ampulla Ampullary- Isthmic Junction Fimbriae Isthmus Uterotubal Junction Adapted from Hafez, 1993 Site of ovulation

  11. Oocyte in the oviduct Uterotubal Junction Ampullary- isthmic Junction Fimbriae Isthmus Ampulla • Lifespan of oocyte • 20 to 24 hours after being released from the ovulatory follicle Infundibulum

  12. Oocyte in the oviduct Uterotubal Junction Ampullary- isthmic Junction Fimbriae Isthmus Ampulla • Time to reach uterus from the infundibulum of the oviduct • Approximately 90 hours in cows • Approximately 48 to 72 hours in women • Oocyte must be fertilized at appropriate time to ensure survival of the embryo when it enters the uterus Infundibulum

More Related