Fertilization and Gastrulation

Question 1

What allows sperm to pass through the corona radiata?

Answer 1

hyaluronidase
mucosal proteins
mvmt of tail

Question 2

What stage of development is only present during week 2?

Answer 2

hypoblast

Question 3

What is the corona radiata?

Answer 3

layer of follicular cells from mom that surround the oocyte; the most superficial layer of ovum

Question 4

What does primitive blood come from and where is it formed?

Answer 4

from extraembryonic splanchnic mesoderm

forms in wall of yolk sac

Question 5

What is the prechordal plate?

Answer 5

part of hypoblast that eventually becomes the mouth and organizational center for the head

Question 6

What are the basic steps of egg penetration?

Answer 6

capacitation
passage of sperm through corona radiata
penetration of zona pellucida

Question 7

Where is the mitochondrial sheath on a sperm?

Answer 7

on middle piece of tail

Question 8

What forms the male pronucleus?

What degrades from sperm?

Answer 8

cytoplasmic contents form pronucleus

tail and mitochondria degrade (mito dna only from mom)

Question 9

In the obstetrical/gestational view, when does the calendar start?

Answer 9

Last menstrual period

Question 10

What happens to the primary yolk sac?

Answer 10

splits into 2: secondary goes up against epiblast primary goes to opposite side (remnant of primary umbilical vesicle?)

Question 11

What is the chorion?

Answer 11

3 layers:
extraembryonic somatic mesoderm
cytotrophoblast
syncytiotrophoblast

Question 12

What are the 3 parts of the sperm tail?

Answer 12

middle piece (with mitochondrial sheath)
principal piece
end piece

Question 13

What is the extraembryonic somatic mesoderm?

Answer 13

cells that line the trophoblast and cover the amnion

Question 14

What happens in week 1 of gestation?

Answer 14

Fertilization
Cleavage
Blastocyst
Inner cell mass
Implantation

Question 15

What can hydatidiform moles turn into?

What percentage of them do this?

Answer 15

choriocarcinomas = malignant tumor

3-5%

Question 16

When does the acrosomal reaction occur?

Answer 16

when the sperm touches the zona pellucida

Question 17

What is a complete mole from?

Answer 17

fertilization of empty oocyte –> duplication of sperm

or: fertilization of empty oocyte by 2 sperm

Question 18

What is the trophoblast? When does it occur?

Answer 18

Cells surrounding inner cell mass

day 5 –> degrades day 7

Question 19

When does cleavage occur?

Answer 19

~30 hours after fertilization

Question 20

What is the zona pellucida

Answer 20

meshwork of glycoproteins that surround the oocyte; just deep of corona radiata

Question 21

What is the bilaminar disc and when does it form?

Answer 21

2 discs are of epiblast and primary yolk sac formed of hypoblast
forms in week 2

Question 22

When is implantation?

Answer 22

day 6

Question 23

What is a blastomere?

Answer 23

One of first few cells after fertilization

Question 24

what are the 2 types of extraembryonic mesoderm?

Answer 24

somatic and splanchnic

Question 25

What is the extraembryonic splanchnic mesoderm?

Answer 25

cells that line the yolk sac

Question 26

What is a hydatidiform mole?

Answer 26

benign, giant thing of trophoblast that causes excessive amounts of hCG can be partial or complete

Question 27

Where do choriocarcinomas have a high likelihood to spread to? (6)

Answer 27

``` vagina lungs bone brain liver intestines ```

Question 28

What is the very basic structure of a sperm?

Answer 28

head neck tail

Question 29

What does the trophoblast differentiate into?

Answer 29

cytotrophoblast | cyncytiotrophoblast

Question 30

What is placenta previa?

Answer 30

When placenta implants over cervical os | can be marginal, partial, or total

Question 31

What is capacitation?

Answer 31

glycoprotein coat and seminal PM proteins removed from PM of sperm allow acrosomal reaction to occur

Question 32

What is the extraembryonic coelom?

Answer 32

hollow cavity outside of the embryo

Question 33

Where does fertilization occur?

Answer 33

ampulla of fallopian tube

Question 34

In the ovulatory calendar, when is day 1?

Answer 34

Fertilization

Question 35

What are the derivatives of extraembryonic mesoderm?

Answer 35

connecting stalk primitive blood chorion

Question 36

What is the syncytiotrophoblast and what does it do?

Answer 36

multibucleated cells above embryoblast responsible for implantation releases hCG --> signals to body that you are pregnant

Question 37

What is the cortical reaction?

Answer 37

release of lysosomal enzymes from granules near oocyte pm --> change membrane potential --> inactivates sperm receptors on zona pellucida

Question 38

Where does extaembryonic mesoderm come from? | Where does it go?

Answer 38

cells pull off from hypoblast --> go and coat trophoblast

Question 39

What happens right after the sperm reaches the pm of the oocyte? (step 3)

Answer 39

plasma membranes fuse | head and tail of sperm ender oocyte

Question 40

When is the blastocyst stage? | What is it formed from?

Answer 40

day 5 - 7 | morula cells --> fluid from uterus enters and makes cavity

Question 41

What is the acrosome and its importance?

Answer 41

on head of mature sperm | contains enzymes to penetrate egg

Question 42

What is the connecting stalk and what does it come from?

Answer 42

from extraembryonic somatic mesoderm | forms at embryonic pole and connects embryo to trophoblast

Question 43

What do you do with fertilized embryos that you don't use in IVF?

Answer 43

cryopreserve | good for 21 yrs

Question 44

What is the female pronucleus? what does it fuse with?

Answer 44

nucleus of ovum after it completes meiosis II --> fuses w/ male pronucleus

Question 45

What happens in cleavage?

Answer 45

increase in cell number decrease in cell size embryo size unchanged morula development

Question 46

What are the basic clinical features of a hydatidiform mole? (5)

Answer 46

``` high hCG vaginal bleeding pelvic pressure or pain enlarged uterus morning sickness ```

Question 47

What are the layers surrounding the ovum from outside in?

Answer 47

corona radiata zona pellucida perivitelline space

Question 48

What makes up the epiblast?

Answer 48

ectoderm amnion amniotic cavity

Question 49

What is the cytotrophoblast?

Answer 49

mitotically active stem cell layer surrounding embryoblast and blastocystic cavity

Question 50

When is the morula stage? What does it look like?

Answer 50

day 3 | looks like a bunch of grapes = 16-32 cells

Question 51

What is the zona reaction and when does it occur?

Answer 51

block to polyspermy | occurs once 1 sperm passes through zona pellucida to prevent other sperms to enter

Question 52

What is a partial mole from?

Answer 52

fertilization of normal oocyte by 2 sperms

Question 53

What is the perivitelline space?

Answer 53

layer just superficial of plasma membrane of the oocyte

Question 54

What must degrade for implantation? | At what stage does this occur?

Answer 54

``` zona pellucida blastocyst stage (day 5-7) ```

Question 55

When does gastrulation occur?

Answer 55

week 3

Question 56

What does the primitive streak form from?

Answer 56

epiblast

Question 57

What are the 3 germ layers that form in gastrulation?

Answer 57

ectoderm mesoderm endoderm

Question 58

In what half of the embryo does the primitive streak form?

Answer 58

caudal half

Question 59

What types of tissues are in the cloacal membrane and the prechordal plate? Why is this significant?

Answer 59

only endoderm and ectoderm | There is no blood supply, so membrane ruptures and opens, which is what you want

Question 60

What is a sacrococcygeal teratoma?

Answer 60

benign tumor that is a remnant of the primitive - contains all different types of tissues

Question 61

What is an orapharyngeal teratoma?

Answer 61

huge gross looking tumor coming out of the head of a fetus | we think it is either abnormal germ cell migration or remnant of primitive streak

Question 62

What is the primitive streak and what does it do?

Answer 62

fold in epiblast (which becomes ectoderm) where cells migrate down; ones at the bottom are endoderm, ones in the middle are mesoderm

Question 63

What is the fate of ectoderm?

Answer 63

skin CNS hair nails

Question 64

What is the fate of mesoderm?

Answer 64

connective tissue: blood, muscle, bones heart spleen

Question 65

What is the fate of endoderm?

Answer 65

lungs GI organs bladder glands

Question 66

Where is the notochord?

Answer 66

extends from primitive node anterior to prechordal plate (head/mouth)

Question 67

What is the notochord important for?

Answer 67

template for vertebral column (does not become spinal cord) | induces ectoderm above it to become neural tissue

Question 68

What tissue is the notochord made of? | where does it lie

Answer 68

mesoderm | in between endoderm and ectoderm

Question 69

When the notochord canal closes, what does it fuse with to form?

Answer 69

fuses with endoderm | forms notochordal plate

Question 70

What are chordomas? | What are they from?

Answer 70

Rare, slow-growing, yet aggressive tumors in skeleton; usually in skull and sacral regions arise from remnants of notochord

Question 71

What is the allantois?

Answer 71

loop of endoderm formed from wall of yolk sac at posterior midline template for umbilical arteries and vein

Question 72

What does the allantois become that is important for the bladder?

Answer 72

urachus

Question 73

What are the 3 types of mesoderm?

Answer 73

Paraxial Intermediate Lateral plate

Question 74

What is the fate of paraxial mesoderm?

Answer 74

somites: muscle, skeleton, dermis

Question 75

What is the fate of intermediate mesoderm?

Answer 75

urogenital: kidneys and gonads

Question 76

What is the fate of lateral plate mesoderm?

Answer 76

connective tissue: blood, lymph, mesenteries, cardiovascular

Question 77

What is the intraembryonic coelom?

Answer 77

space in intermediate mesoderm that becomes body cavities