MCP 22: Fertilization

Question 1

How many cells in human body?

Answer 1

10 trillion

Question 2

How many different types of cells?

Answer 2

250 (including some stem cells)

Question 3

oviduct

Answer 3

Fallopian tube-like structure in non-humans

Question 4

ampulla region

Answer 4

where fertilization occurs in Fallopian tube

Question 5

other terms for fertilization

Answer 5

conceptions, fecundation, syngamy

Question 6

granulosa cells

Answer 6

cells that surround the secondary oocyte

Question 7

corona radiata

Answer 7

collection of granulosa cells that surround the secondary oocyte, multiple sperm make contact with the corona radiata

Question 8

secondary oocyte

Answer 8

egg is arrested in metaphase II

Question 9

active forward motility

Answer 9

how the sperm approaches the egg, tail spins to propel it forward

Question 10

hyperactive motility

Answer 10

other way for sperm to meet with egg, tail flails around, not as effective as active forward motility

Question 11

acrosome

Answer 11

tip of sperm

Question 12

hyaluronidase

Answer 12

decreases adhesions between the granulosa cells so the sperm can wiggle in

Question 13

acrosin

Answer 13

enzyme that eats away ate zona pellucida

Question 14

zona pellucida

Answer 14

egg shell, thick later of extracellular matrix material surrounding the oocye

Question 15

theories for egg/sperm fusion

Answer 15

1. ) sperm membrane protein fertilin binds to integrin receptors on egg 2.) sperm releasing calcium and activating tyrosine receptors on egg
   * *multiple theories could be correct so the sperm has multiple avenues to merge with the egg**

Question 16

fertilin

Answer 16

sperm membrane protein responsible for binding with egg

Question 17

What happens when the sperm binds to the egg?

Answer 17

1.) sperm does NOT bind head on 2.) egg releases a wave of calcium upon binding

Question 18

What happens after the egg releases calcium upon sperm/egg fusion?

Answer 18

1.) Meiosis is reactivated; forms mature ovum and second polar body 2.) signals organelles called cortical granules to exocytose contents between plasma membrane and zona pellucida

Question 19

cortical granules

Answer 19

blocks polyspermy by hardening the zona pellucida

Question 20

continuation of meiosis after fertilization

Answer 20

progress through S phase, nuclear material mixes once membranes fall apart, chromosomes undergo mitosis in a single cell creating a diploid organism

Question 21

3 to 4 days post fertilization

Answer 21

1.) division continues and each cell is called a blastomere

Question 22

blastomere

Answer 22

what each cell is called 3-4 days after fertilization until the cell reaches the morula (12-cell) phase, cells become progressively smaller because they are limited in size by the zona pellucida

Question 23

morula

Answer 23

when the 12-cell stage is reached, compaction occurs

Question 24

compaction

Answer 24

occurs at the 12-stage cell cycle 1.) cells begin to flatten and form junctions, differentiation begins because cells on the inside have different environments than those on the outside 3.) outer cells form Na/K ATPase pumps to set up concentration gradient

Question 25

inner cell mass

Answer 25

cells that are pluripotent (can differentiate into anything), source of stem cell controversy, embryo develops from these cells

Question 26

early blastocyst phase

Answer 26

formation of blastocyst occur in uterus, blastocoel cavity forms, if this doesn’t happen, zygote will degenerate

Question 27

blastocoel cavity

Answer 27

fluid-filled cavity that forms in the early blastocyst phase, Na/K ATPase pumps create sodium gradient which causes water to rush into cell and fill bastocoel

Question 28

late blastocyst phase

Answer 28

when the egg hatches from the zona pellucida and is ready to implant in the uterus

Question 29

three layers of the uterus

Answer 29

endometrium, myometrium, and perimetrium

Question 30

implantation in uterus

Answer 30

1.) hatched blastocyst implants into endometrium closest to the inner cell mass

Question 31

embryonic pole

Answer 31

the direction that the late blastocyst implants into the endometrium

Question 32

layers of the endometrium

Answer 32

basal, spongy and compact

Question 33

basal layer of endometrium

Answer 33

contains its own blood supply and is not sloughed off during menstruation

Question 34

timeline of hormones during early follicular phase

Answer 34

1.) hypothalamus secretes releasing factors that act on anterior pituitary 2.) anterior pituitary releases FSH 3.) FSH causes follicles to grow 4.) one follicle closes to the blood supply around 6-8 days will become the dominant follicle 5.) mature follicle secretes estrogen that inhibits FSH release and causes the epithelium to proliferate

Question 35

timeline of hormones during the mid follicular phase

Answer 35

1.) dominant follicle submits estrogen for 150pg/ml for ~36 hrs and estrogen starts to have a positive feedback mechanism on FSH production 2.) more follicles produced 3.) surge in LH 4.) LH surge increases progesterone 5.) progesterone stimulates enzyme to degrade wall of follicle and release egg

Question 36

timeline of hormones in luteal phase

Answer 36

1.) elevated progesterone levels inhibit FSH production, stops production of new follicles 2.)if not implantation occurs 12 days after ovulation, follicle degenerates, estrogen and progesterone production decreases, FSH production increases and new follicles are formed, mensus

Question 37

corpus luteum

Answer 37

unlucky follicles that did not become the dominant follicles

Question 38

What happens when implantation occurs?

Answer 38

corpus luteum remains intact and continues to secrete estrogen and progesterone, cells from implanted embryo (syncitiotrophoblast) will secrete human chorionic gonadotropin (hCG)on positive feedback loop on corpus luteum

Question 39

syncitiotrophoblast

Answer 39

trophoblast differentiated into this tissue when binds to endometrium, multinucleated, dissolves connections between the endometrium and allows embryo to invade, secretes human chorionic gonadotropin (hCG)on positive feedback loop on corpus luteum

Question 40

rise in body temperature

Answer 40

elevated levels of estrogen and progesterone raise woman’s body temperature

Question 41

RU486

Answer 41

birth control that acts as a competitive inhibitor of progesterone, 2mg daily low dose used for contraception, high 10mg dose used for Plan B; uterus thinks no progesterone is present

Question 42

twins

Answer 42

chances of having twins=1 in 90, chances of having triples 1 in 90 squared

Question 43

dizygotic twins

Answer 43

2/3 of twins are dyzygotic, two separate eggs and two separate sperm, different placents

Question 44

monozygotic

Answer 44

division occurs during the blastocyst phase when the inner cell mass divides, these cells are pluripotent, thus identical twins

Question 45

differences between clones and twins

Answer 45

clones have shortened ends of chromosomes, are less viable, may be larger and often exhibit premature aging

Question 46

cavitation

Answer 46

formation of blastocoel

Question 47

fertilization

Answer 47

starts with contact between sperm and secondary oocyte, ends with fusion of paternal and maternal nuclei

Question 48

zona reaction

Answer 48

when cortical granules on the innermost side of the oocyte plasma membrane are released into the perivitelline space

Question 49

perivitelline space

Answer 49

between zone pellucida and plasma membrane/cytoplasm of egg

Question 50

sperm plasma membrane

Answer 50

fuses with that of the egg, sperm head and tail enter ooctye but plasma membrane remains behind

Question 51

female pronucleus

Answer 51

mature oocyte that forms after meiosis resumes post fertilization, second polar body also formed

Question 52

formation of male pronucleus

Answer 52

after in the oocyte cytoplasm, nucleus of sperm decondenses, tail degenerates, and male pronucleus formed–difficult to discern male and female pronuclei, but female pronucleus is slightly larger