Fertilization and Gastrulation

Question 1

Obstetrical calendar (gestational calendar)

Answer 1

start date is based on when the LNMP was

- includes weeks -2, -1

Question 2

Ovulatory calendar

Answer 2

start date based on when fertilization occurred

Question 3

corona radiata

Answer 3

outermost layer of cells from the ovum; made of follicular cells that radiate out

Question 4

zona pellucida

Answer 4

glycoprotein mesh work outside the ovum; important in process of fertilization

Question 5

perivitelline space

Answer 5

the space between the zona pellucida and the cell membrane of an oocyte or fertilized ovum

Question 6

acrosome

Answer 6

part of sperm in the head; contains enzymes that are needed to get through the different layers outside the ovum

Question 7

why does the sperm have mitochondria in the tail

Answer 7

to produce ATP in order to propel the flagella of the sperm

Question 8

5 important events in week 1 of fertilization

Answer 8

1. fertilization
2. cleavage
3. formation of blastocyst
4. formation of inner cell mass (embryoblast)
5. implantation

Question 9

where does fertilization occur

Answer 9

in the ampulla of the uterine tube (fallopian tube)

Question 10

capacitation

Answer 10

the glycoprotein coat and seminal plasma proteins are removed from the plasma membrane of the sperm to allow the acrosome reaction; occurs int he uterus and uterine tubes; takes about 7 hours

Question 11

what enzyme is released by the sperm to get through the corona radiata

Answer 11

hyaluronidase

Question 12

what three enzymes does the sperm release to get through the zona pellucida

Answer 12

esterases, acrosin, neuraminidase

Question 13

what is the significance of the zona reaction

Answer 13

blocks polyspermy

Question 14

features of the zona reaction

Answer 14

• conformation change in the zona pellucinda
• mesh work becomes rigid
• blocks any more sperm to enter

Question 15

True or False: the sperm mitochondria enter the oocyte

Answer 15

false

Question 16

5 key results from fertilization

Answer 16

1. completion of second meiotic division
2. restoration of diploid # chromosomes
3. determination of chromosomal sex of embryo
4. metabolic activation of oocyte
5. initiation of cleavage

Question 17

Morula

Answer 17

develops at around day 3; consists of 12-32 cells; when it enters the body of the uterus fluid begins to diffuse in which forms the blastocyst cavity forming the blastocyst (at around day 5)

Question 18

what day does the blastocyst develop

Answer 18

day 5

Question 19

when does cleavage start

Answer 19

30 hours after fertilization

Question 20

when does the morula enter the uterus

Answer 20

day 3 or 4

Question 21

what does the inner cell mass give rise to

Answer 21

the epiblast

Question 22

when does the zona pellucida start to degenerate

Answer 22

day 5 (is gone by day 7)

Question 23

what does the trophoblast give rise to

Answer 23

the placenta

Question 24

what form is the embryo in at one week

Answer 24

one cell layer

Question 25

3 types of assisted reproductive strategies

Answer 25

1. in vitro fertilization and embryo transfer 2. cryopreservation of embryos 3. intracytoplasmic sperm injection

Question 26

in vitro fertilization and embryo transfer

Answer 26

- stimulate mother's ovaries and collect eggs - collect sperm from dad - capacitate the sperm - implant 1-3 embryos

Question 27

Cryopreservation of embryos

Answer 27

freezing embryos in liquid nitrogen; viable for up to 21 days

Question 28

intracytoplasmic sperm injection - when is it used - what is it

Answer 28

used when sperm count is low; inject the egg cell with the sperm cell so that it will become fertilized

Question 29

where do we get embryonic stem cells

Answer 29

cryopreserved embryos

Question 30

somatic cell nuclear transfer

Answer 30

taking the nucleus out of an adult cell and putting it in an oocyte without a nucleus --> therapeutic cloning

Question 31

the trophoblast gives rise to the

Answer 31

cytotrophoblast

Question 32

the cytotrophoblast gives rise to the

Answer 32

synctiotrophoblast

Question 33

cytotrophoblast

Answer 33

stem cell layer that is mitotically active; keeps multiplying and gives rise to the synctiotrophoblast

Question 34

synctiotrophoblast

Answer 34

multinucleated cells that contain proteolytic enzymes that are responsible for implantation; release chorionic gonadotrophin (HCG); don't have plasma membranes

Question 35

what releases human chorionic gonadotrophin (HCG)

Answer 35

the synctiotrophoblast

Question 36

hydatidiform mole

Answer 36

abnormal trophoblast proliferation with excessive amounts of HCG produced

Question 37

two ways in which a complete hydatidiform mole can occur

Answer 37

1. fertilization of an empty oocyte followed by duplication of the sperm (zona reaction occurred) 2. fertilization of an empty oocyte by two sperm (zona reaction did not occur)

Question 38

how can a partial hydatidiform mole form

Answer 38

fertilization of a normal oocyte by two sperm

Question 39

clinical features of a hydatidiform mole

Answer 39

``` positive pregnancy test vaginal bleeding pelvic pressure/pain enlarged uterus hyperemesis gravidarum (morning sickness) ```

Question 40

choriocarcinomas

Answer 40

malignant tumor that develops from hydatidiform mole; spread to liver, lungs, vagina, intestines, bone, and brain

Question 41

when does implantation start and finish

Answer 41

day 6 - day 10

Question 42

what three things does the epiblast give rise to

Answer 42

ectoderm amnion amnion cavity

Question 43

what does the hypoblast give rise to

Answer 43

extraembryonic endoderm

Question 44

endoderm gives rise to:

Answer 44

prechordal plate primary and secondary yolk sacs extraembryonic mesoderm

Question 45

prechordal plate

Answer 45

large group of cells that fuse to cells of the epiblast which is the location of the future mouth; the organization center for the formation of the head

Question 46

what does the hypoblast act as a placeholder for

Answer 46

the bilaminar disc

Question 47

extraembryonic coelom

Answer 47

hollow cavity outside the embryo

Question 48

what does extraembryonic somatic mesoderm line

Answer 48

lines the trophoblast and covers the amnion

Question 49

what does extraembryonic splanchnic mesoderm line

Answer 49

lines the yolk sac

Question 50

connecting stalk - origin - what does it become

Answer 50

part of the extraembyronic somatic mesoderm; forms at the embryonic pole; becomes the umbilical cord

Question 51

primitive blood - origin - where does it form

Answer 51

part of the extraembryonic splanchnic mesoderm; forms in the wall of the yolk sac

Question 52

chorion - origin - what's it made of - what does it become

Answer 52

part of the extraembryonic somatic mesoderm; one of the layers of the placenta; made up of cytotrophoblast and synctiotrophoblast

Question 53

placenta previa

Answer 53

vaginal bleeding beyond 20 weeks of gestation

Question 54

marginal placenta previa

Answer 54

placenta is right on the margin of the internal cervical os, causing vaginal bleeding

Question 55

partial placenta previa

Answer 55

placenta is covering half of the internal cervical os, causing vaginal bleeding

Question 56

total placenta previa

Answer 56

placenta is completely covering the internal cervical os, causing vaginal bleeding

Question 57

why must you do a US instead of a digital vaginal exam with placenta previa

Answer 57

palpation of the placenta can cause severe hemorrhage

Question 58

when does gastrulation occur

Answer 58

week 3

Question 59

gastrulation

Answer 59

the formation of the three primary germ layers

Question 60

the mesoderm gives rise to

Answer 60

- connective tissue layers of the body - muscle - bone - blood - heart - spleen

Question 61

the ectoderm gives rise to

Answer 61

- skin - hair - nails CNS (brain and spinal cord)

Question 62

the endoderm gives rise to

Answer 62

- lungs - GI tract organs - bladder - most of the glands (thyroid, parathyroid, etc.)

Question 63

primitive streak

Answer 63

marks the start of gastrulation, the process in which the inner cell mass in converted into the trilaminar embryonic disc, which is comprised of the three germ layers - forms in the caudal region

Question 64

the septum transversum develops into the

Answer 64

diaphragm

Question 65

the cardiogenic area develops into the

Answer 65

heart

Question 66

the cloacal membrane develops into the

Answer 66

urogenital system

Question 67

cleavage

Answer 67

increase in cell number and decrease in cell size; embryo size is unchanged; morula develops