Part of Week 1 and All of Week 2 Human Development

Question 1

when does fertilization end?

Answer 1

intermingling of chromosomes at metaphase of zygote’s first mitotic division

Question 2

how long does fertilization take?

Answer 2

24 hours

Question 3

first 4 phases of fertilization

Answer 3

1 - sperm capacitated through uterus

2- sperm goes through corona radiate (help from hyaluronidase released from acrosome and tail)

3- sperm penetrates zona pellucida (help from across, esterase, and neuraminidase)

penetration by another sperm now impossible

4- sperm membrane fuses to oocyte membrane, nuclear material enters cell

Question 4

what part of the sperm does NOT enter the oocyte membrane?

Answer 4

sperm plasma membrane and mitochondria

Question 5

final phases of fertilization

Answer 5

5- sperm penetrates oocyte membrane, meiosis II completes&raquo_space; mature oocyte + second polar body

6- sperm tail degenerates

7- male and female pronuclei chromosomes replicate&raquo_space;ootid

8- pronuclei of ootid fuse to form zygote

9- chromosomes align on cleavage spinal

10- metabolic activation which causes cleavage

Question 6

maternal chromosomes decondense and form what?

Answer 6

female pronucleus

Question 7

nucleus of the sperm enlarges to form what?

Answer 7

male pronucleus

Question 8

when is meiosis II of the oocyte completed?

Answer 8

when penetration of oocyte occurs

Question 9

what are the results of fertilization?

Answer 9

• completes meiosis II of oocyte
• restores normal diploid number of chromosomes (46, 2N)
• creates genetic variation
• determines gender
• initiates cleavage of zygote

Question 10

what is used to stimulate ovarian follicle growth and maturity?

Answer 10

• clomiphene citrate

- gonatotropin

Question 11

when does cleavage occur?

Answer 11

30 hours after fertilization

Question 12

what is still surrounded by zona pellucida during cleavage?

Answer 12

blastomeres

Question 13

what are 12-32 blastomeres called?

Answer 13

morula

Question 14

when does the morula enter the uterus and blastocyst cavity starts to appear?

Answer 14

4 days after fertilization

Question 15

blastomere is separated into what 2 parts, because of the fluid?

Answer 15

• trophoblast (placenta, thin outer layer)

- embryoblast (embryo, centrally located)

Question 16

what do the trophoblast cells secrete?

Answer 16

early pregnancy factor

Question 17

when will early pregnancy factor appear in mother’s serum?

Answer 17

24-48 hours after fertilization

Question 18

what can expand when the zona pellucida degenerates after 2 days?

Answer 18

blastocysts

Question 19

what happens 6 days after fertilization?

Answer 19

• blastocyst attaches to endometrial epithelium

- trophoblasts proliferate

Question 20

2 layers of trophoblast proliferation

Answer 20

• cytotrophoblast (inner)

- synctiotrophoblast (outer)

Question 21

which trophoblast layer has a multinucleated mass and no cell boundaries?

Answer 21

synctiotrophoblast

Question 22

which trophoblast layer produces enzymes to erode maternal tissues so the embryo can burrow into the endometrium?

Answer 22

synctiotrophoblast (end of week 1)

Question 23

what hormone does the synctiotrophoblast secrete that maintains the hormonal activity of the corpus luteum?

Answer 23

hCG - human chorionic growth hormone

Question 24

what hormones does the corpus luteum secrete?

Answer 24

estrogen and progesterone

Question 25

what forms the amnion?

Answer 25

amnioblasts separated from the epiblast

Question 26

what forms the embryonic disc?

Answer 26

embryoblast

Question 27

2 layers of the embryonic disc

Answer 27

• epiblast

- hypoblast

Question 28

which layer of the embryonic disc is thicker columnar cells making the floor of the amniotic cavity?

Answer 28

epiblast

Question 29

which layer of the embryonic disc is thinner cuboidal cells and forms the primary umbilical vesicle?

Answer 29

hypoblast

Question 30

what makes up the primary umbilical vesicle?

Answer 30

• hypoblast
• roof of exocoelomic cavity
• exocoelomic membrane