OB CONCEPTION

1. THE PROCESS OF CONCEPTION

2. OVA Released from the Graafian Follicle Will be surrounded by a ring of mucopolysaccharide fluid (Zonapellucida) and a circle of cells (Corona radiata) Zonapellucida and Corona Radiata protects the ova by serving as a buffer against injury Moves from the ovary to the fallopian tube through the cilia and peristaltic movement of fallopian tube

3. SPERM Per ejaculation, 2.5ml semen containing 50-200M spermatozoa is released (ave 400M sperm/ejaculation) Moves through the cervix, uterus, fallopian tube because of their flagella and uterine contractions Undergoes CAPACITATION (changes in the plasma membrane of the sperm head to reveal sperm binding receptor sites) before penetrating into the corona radiata

4. Sperm clusters around coronal cells Will release HYALURONIDASE (proteolytic enzyme) to dissolve the corona radiata Sperm penetrates the cell; cell membrane of ova changes composition to become impenetrable to other sperm

5. Sperm and ova fuse carrying 23 pairs of chromosomes each If sperm carries X sex chromosome paired with the ovum X chromosome = female zygote If sperm carries Y sex chromosome paired with the ovum X chromosome = male zygote

6. IMPLANTATION Zygote move from fallopian tube to uterus 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 Once it reaches the uterus, zygote is now composed of 32 -50 ball of cell termed as a MORULA

7. Another 3-4 days, morula becomes a BLASTOCYST consisting of: An inner cell mass which will become the future embryo Trophoblast which will become the placenta and membranes

8. At approx 8-10 days after fertilization, blastocyst attaches to the endometrium Sheds off last residues of corona radiata and zonapellucida Brushes against endometrium (apposition) and settles down A slight vaginal bleeding is experienced during implantation stage because capillaries are ruptured by the implanting trophoblast cells

10. Deciduacapsularis – portion that stretches or encapsulates the surface of the trophoblast

12. They begin the formation of the placenta

15. Has 25-30 cotyledons (placental compartments that lie on the maternal side)

16. Has 2 sides

17. Maternal – dirty rough

19. Secretes endocrine hormones (syncytial cells)

20. hCG – 1st placental hormone - enusures corpus luteum to continuously produce progesterone and estrogen - supresses maternal immunologic reaction so that placental tissue is not detected and rejected as a foreign substance

24. Slightly alkaline pH 7.2

26. Protects fetus from temperature change

27. Aids in muscular development because it allows fetus’ freedom to move

30. Amniotic membrane – 2nd membrane lining the chorionic membrane; forms beneath the chorion - produces amniotic fluid - produces phospholipid that initiates the formation of prostaglandins which can cause uterine contractions and may be the trigger that initiates labor

32. 53cm (21 in) length; 2 cm thick

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. Outer surface is covered with amniotic membrane

36. Walls are with smooth muscles, no nerve supply

37. Function: