Development

Question 1

the formation of primary germ layers begins at ______.

Answer 1

8 weeks

Question 2

ectoderm derives into (4)

Answer 2

• epidermis
• lens and cornea
• nervous system
• internal ear

Question 3

mesoderm derives into (4)

Answer 3

• skeleton
• muscle
• lymphoid tissues
• kidney and ureters

Question 4

endoderm derives into (3)

Answer 4

• gut
• respiratory epithelium and glands
• bladder

Question 5

placenta

Answer 5

• 3cm thick disc

- surface facing fetus is smooth and connected to umbilical cord

Question 6

placenta is important because it ensures_____

Answer 6

the fetal and mothers blood do not mix

Question 7

what increases as the placenta villi grow

Answer 7

conductivity

Question 8

placentation

Answer 8

• starts around day 11

- include both the mother and embryonic tissue

Question 9

syncytiotrophoblast… (during placentation) and the mesenchyme….

Answer 9

grows into chorionic villi; form blood vessels from the embryoblast

Question 10

chorionic vill… (during placentation)

Answer 10

digest lacunae spaces that fill with maternal blood

Question 11

what forms the placenta (2)

Answer 11

stratum deciduas with the chorionic villi

Question 12

ectopic pregnancy (2)

Answer 12

• blastocyst implants outside the uterus

- most of the time in the uterine tube that ruptures after 12 weeks

Question 13

capacitation

Answer 13

sperm must remove a layer of cholesterol and inhibitory factors from the acrosomal vesicle that require the females secretions

Question 14

following capacitation the sperm are

Answer 14

fragile, will last only 48 hours post ejaculation

Question 15

what is the window of opportunity for pregnancy (2)

Answer 15

48 hours before ovulation

12-24 hours after

Question 16

what is the last step of sperm for fertilization

Answer 16

capacitation

Question 17

the first sperms to arrive must? how is this accomplished

Answer 17

breakdown the corona radiata; release of hyaloronidases following the acrosomal reaction

Question 18

the second wave of sperm….

Answer 18

attach to receptors on the zona pellucida and also trigger acrosomal reaction

Question 19

the first sperm to penetrate the zona pellucida….

Answer 19

will fuse with the plasma membrane of the egg and release its pronuclei

Question 20

polyspermy

Answer 20

more than 1 sperm entering an egg

Question 21

what are the mechanisms to prevent polyspermy?

Answer 21

fast block

slow block

Question 22

fast block (3)

Answer 22

• penetration depolarizes the egg and causes opening of voltage sensitive sodium channels
• occurs throughout the egg
• inactivates sperm receptors on the egg

Question 23

slow block (3)

Answer 23

• depolarization of the fast block causes calcium sensitive channels to open
• calcium causes release of cortical granules that are spread between the egg and zona pellucida
• fluid begins to fill the area between the zona and egg

Question 24

zygote

Answer 24

fertilized egg

Question 25

cleavage (2)

Answer 25

• rapid mitosis without growth

- occurs 30 hours post fertilization

Question 26

hatching (3)

Answer 26

• cell mass no longer undergoing cleavage
• time egg feeds on uterine milk
• blastocyst begins to form

Question 27

blastocyst

Answer 27

a hollow sphere with an outer layer and inner layer

Question 28

inner layer of blastocyst

Answer 28

embryoblast (becomes embryo)

Question 29

outer layer of blastocyst

Answer 29

trophoblast (becomes chorion)

Question 30

chorion

Answer 30

fetal part of the placenta

Question 31

dizygotic twins (2)

Answer 31

• fraternal twins

- 2 eggs ovulated and fertilized

Question 32

monozygotic twins (2)

Answer 32

• splitting of the embryoblast

- maternal twins

Question 33

syncytiotrophoblast (3)

Answer 33

• fusion of the trophoblast
• secretes HCG
• becomes chorion