Fertilization

Question 1

sperms anatomical journey once ejaculated

Answer 1

• swim up the cervical canal

- drawn up through the uterus and fallopian tubes by muscular contractions and ciliary movemements

Question 2

fertilization occurs where in the uterin (fallopian) tube?

Answer 2

ampulla

-however, it may occur elsewhere in the tube but not in the uterus

Question 3

what the does the actual act of fertizilation begin with

Answer 3

-contact between the sperm and secondary oocyte (eureka moment)

Question 4

fertilization ends with

Answer 4

-intermingling of maternal and paternal chromosomes at metaphase of the first zygotic division approximately 24 hours later (the end of eureka day)

Question 5

corpus luteums role in supporting pregnancy in the first 20 weeks

Answer 5

-secreting progesterone that helps maintain a functional endometerial layer in the uterus

Question 6

Leutinizing hormone and hCG produced by the embryo..

Answer 6

-keep the corpus luteum in tip-top, progesterone secreting shape

Question 7

one of the top 3 causes of spontaneous shmashmortion

Answer 7

-insufficient progesterone production

Question 8

progesterone supplementation

Answer 8

-for women who have had two or more spontaneous abortions

Question 9

sperm transport

Answer 9

-sperm are mostly propelled by contraction of uterine smooth muscle cells

Question 10

capacitation

• why do we need it, 2 reasons
• what happens if we dont have it
• IVF mimic

Answer 10

• this reaction is critical to fertility because it enables sperm to swim well
• prepares them for the acrosome reaction
• if this does not occur than the sperm are useless and infertility will result
• mimicked in IVF clinics by washing the sperm with base

Question 11

acrosome reaction

Answer 11

• happens when the sperm come in contact with the follicular cells surrounding the oocyte
• the acrosome membrane perforates, releasing enzymes that can chew up the matrix and the zona pellicuda
• this allows the sperm to enter the zona pellicuda and fuse with the oozyte plasma membrane (eureka!)

Question 12

cortical reaction

Answer 12

• fusion of the sperm and oocyte plasma membrane causes calcium pulses in the oocyte
• this triggers the cortical granules to exocytose (secrete) their contents (enzymes)
• these enzymes cross link the proteins in the zona pellucida preventing any addition sperm penetration
• this is critical in blocking polyspermy which can lead to aneuploidy and embryonic/neonate lethals

Question 13

sequence of events in fertilization

Answer 13

1. ejaculation
2. capacitation
3. acrosome reaction
4. fusion of sperm and oocyte membranes
5. cortical reaction
6. completion of meiosis 2 in oocyte
7. fusion of the male and female pronuclei