The process of conception


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The process of conception

  2. 2. OVA<br />Released from the Graafian Follicle<br />Will be surrounded by a ring of mucopolysaccharide fluid (Zonapellucida) and a circle of cells (Corona radiata)<br />Zonapellucida and Corona Radiata protects the ova by serving as a buffer against injury<br />Moves from the ovary to the fallopian tube through the cilia and peristaltic movement of fallopian tube<br />
  3. 3. SPERM<br />Per ejaculation, 2.5ml semen containing 50-200M spermatozoa is released (ave 400M sperm/ejaculation)<br />Moves through the cervix, uterus, fallopian tube because of their flagella and uterine contractions<br />Undergoes CAPACITATION (changes in the plasma membrane of the sperm head to reveal sperm binding receptor sites) before penetrating into the corona radiata<br />
  4. 4. Sperm clusters around coronal cells<br />Will release HYALURONIDASE (proteolytic enzyme) to dissolve the corona radiata<br />Sperm penetrates the cell; cell membrane of ova changes composition to become impenetrable to other sperm<br />
  5. 5. Sperm and ova fuse carrying 23 pairs of chromosomes each<br />If sperm carries X sex chromosome paired with the ovum X chromosome = female zygote<br />If sperm carries Y sex chromosome paired with the ovum X chromosome = male zygote<br />
  6. 6. IMPLANTATION<br />Zygote move from fallopian tube to uterus<br />It will undergo series of mitotic divisions resulting to a cleavage formation, 1 in every 22 hour, with the cleavage division happening 24 hours after fertilization<br />Once it reaches the uterus, zygote is now composed of 32 -50 ball of cell termed as a MORULA<br />
  7. 7. Another 3-4 days, morula becomes a BLASTOCYST consisting of:<br />An inner cell mass which will become the future embryo<br />Trophoblast which will become the placenta and membranes<br />
  8. 8. At approx 8-10 days after fertilization, blastocyst attaches to the endometrium<br />Sheds off last residues of corona radiata and zonapellucida<br />Brushes against endometrium (apposition) and settles down<br />A slight vaginal bleeding is experienced during implantation stage because capillaries are ruptured by the implanting trophoblast cells<br />
  9. 9. EMBRYONIC & FETAL STRUCTURES<br />DECIDUA – uterus that has grown thick and vascular<br />3 areas<br /><ul><li>Deciduabasalis – lies directly under the embryo (portion where the trophoblast establish communication with maternal blood vessel)
  10. 10. Deciduacapsularis – portion that stretches or encapsulates the surface of the trophoblast
  11. 11. Deciduavera – the remaining portion of the uterine lining</li></li></ul><li>CHORIONIC VILLI<br /><ul><li>Miniature villi similar to probing fingers that appear on the 11th or 12th day
  12. 12. They begin the formation of the placenta
  13. 13. Consists of a central core of connective tissue and fetal capillaries</li></li></ul><li>Consists of 2 layers of trophoblast cells:<br />Syncytiotrophoblast(syncitial layer) – produces HCG, somatomammotropin (human placental lactogen), estrogen and progesterone<br />Cytotrophoblast (middle or Langhan’s layer) – functions in early pregnancy to protect the growing embryo and fetus from infection (eg syphilis)<br />
  14. 14. PLACENTA<br /><ul><li>15-20CM IN DIAMETER, 2-3 CM DEEP, 400-600g at full term
  15. 15. Has 25-30 cotyledons (placental compartments that lie on the maternal side)
  16. 16. Has 2 sides
  17. 17. Maternal – dirty rough
  18. 18. Fetal – shiny smooth</li></li></ul><li>FUNCTIONS:<br /><ul><li>Serves to conduct oxygen and nutrients for the fetus
  19. 19. Secretes endocrine hormones (syncytial cells)
  20. 20. hCG – 1st placental hormone</li></ul> - enusures corpus luteum to continuously produce progesterone and estrogen<br /> - supresses maternal immunologic reaction so that placental tissue is not detected and rejected as a foreign substance<br />
  21. 21. - if fetus is male, stimulates the testes to begin producing testoterone<br /> - at 8 week, begins progesterone production, as a result, CL disintegrates and hCG production decreases<br /><ul><li>ESTROGEN (estriol) – “hormone of women”</li></ul> - contributes to mammary gland development of mother in preparation for lactation<br /> - stimulates uterine growth to accommodate growing fetus<br />
  22. 22. <ul><li>PROGESTERONE - “Hormone for Mothers”</li></ul> - necessary to maintain endometrial lining of the uterus during pregnancy<br /> - reduces contractility of uterus during pregnancy preventing preterm labor<br /><ul><li>HUMAN PLACENTAL LACTOGEN (human chorionic somatomammotropin)</li></ul> - with both growth promoting and lactogenic (milk producing) properties<br /> - promotes mammary gland (breast) growth in preparation for lactation<br />
  23. 23. - regulates maternal glucose, protein and fat levels so that adequate amounts of these are always available to the fetus<br />AMNIOTIC FLUID<br /><ul><li>800-1200ml
  24. 24. Slightly alkaline pH 7.2
  25. 25. Fetal urine adds to its volume</li></li></ul><li>Functions:<br /><ul><li>Shields fetus against pressure or blow to the mother’s abdomen
  26. 26. Protects fetus from temperature change
  27. 27. Aids in muscular development because it allows fetus’ freedom to move
  28. 28. Protects the umbilical cord from pressure protecting fetal oxygen supply</li></li></ul><li>Hydramnios – excessive amniotic fluid<br /> - more than 2000ml or pockets of fluid larger than 8cm on UTZ<br />Oligohydramnios – reduction in the amount of amniotic fluid<br /> - less than 300ml or no pockets of fluid larger than 1 cm on UTZ<br />
  29. 29. AMNIOTIC MEMBRANES<br /><ul><li>Chorionic membrane – the outermost fetal membrane; purpose is to form a sac that contains the amniotic fluid
  30. 30. Amniotic membrane – 2nd membrane lining the chorionic membrane; forms beneath the chorion</li></ul> - produces amniotic fluid<br /> - produces phospholipid that initiates the formation of prostaglandins which can cause uterine contractions and may be the trigger that initiates labor<br />
  31. 31. UMBILICAL CORD<br /><ul><li>Formed from the amnion and chorion
  32. 32. 53cm (21 in) length; 2 cm thick
  33. 33. Wharton’s jelly – a gelatinous mucopolysaccharide that forms the bulk of the umbilical cord giving it its body; prevents pressure on the veins and arteries
  34. 34. Outer surface is covered with amniotic membrane
  35. 35. Composed of 1 vein (carrying blood from placental villi to the fetus) and 2 arteries (blood from fetus back to palcentalvilli)</li></li></ul><li><ul><li>Blood flow is 350ml/min at term
  36. 36. Walls are with smooth muscles, no nerve supply
  37. 37. Function:
  38. 38. Transports oxygen and nutrients to the fetus from placenta and return waste products from fetus to placenta</li></li></ul><li>