Lecture 1

Question 1

Human embryonic development takes an average of ____________ and is composed of two stages __________

Answer 1

38 weeks.

• embryonic period
• Fetal period

Question 2

First 8 weeks of embryonic development is called _______________

Answer 2

Embryonic Period

Question 3

remaining 30 weeks of embryonic development is called___________________

Answer 3

Fetal Period.

Question 4

_________ develops in ovary.

Answer 4

Oocyte

Question 5

After ovulation, THE Oocyte IS transported to ______ by __________________

Answer 5

uterus, uterus by muscular contractions of the fallopian tube and the cilia lining the tube.

Question 6

Oocyte is a _________ cell

Answer 6

haploid cell, containing only 1 copy of each chromosome

Question 7

The Oocyte remains ______ within the fallopian tube for approximately 12 hours.

Answer 7

viable

Question 8

The oocyte is surrounded by a ___________, a thick extracellular matrix called ___________

Answer 8

plasma membrane

zona pellucida

Question 9

The additional layer of cells that surround the oocyte

Answer 9

the corona radiata.

Question 10

Sperm are___________ and are attracted to the oocyte.

Answer 10

haploid cells

Question 11

Sperm ______________ a pathway through these membranes to fertilize the oocyte.

Answer 11

enzymatically digest

Question 12

Critical that only one sperm fertilizes the oocyte, and all others are inhibited______________ after the first sperm has entered

Answer 12

by chemical changes

induced in the zona pellucida

Question 13

Unequal contribution of cytoplasm -

Answer 13

small amount of cytoplasm derived from the sperm compared

to the enormous amount derived from the oocyte.

Question 14

Sperm and oocyte contribute

Answer 14

equal amounts of genetic material

Question 15

Nuclear fusion takes ______________

Answer 15

approximately 12 hours

Question 16

______________ the formation of a single diploid cell from the two haploid cells oocyte and sperm

Answer 16

nuclear fusion

Question 17

24 hr after fertilization the __________ forms from _________

Answer 17

mammalian zygote, cleavage

Question 18

___________ the series of mitotic divisions by

which the enormous volume of egg cytoplasm is divided into smaller cells.

Answer 18

cleavage,

Question 19

Cells formed by cleavage divisions are called _____________

Answer 19

blastomeres.

Question 20

As cleavage continues, more cells are formed. ______________ continues to surround the cells,
maintaining a constant diameter of the embryo.

Answer 20

The zona pellucida

Question 21

At the 16-32 cell stage, the embryo is called __________

Answer 21

a morula.

Question 22

During morula stage, Initially dividing cells are round, but then

Answer 22

become compacted with junctions between them.

Question 23

• Embryo differentiates into ___________________

Answer 23

external and internal cells

Question 24

Sphere of ________________ will become the embryonic contribution to the placenta.

Answer 24

external cells

Question 25

Inside the sphere are a small number of__________ that give rise to the embryo.

Answer 25

internal cells

Question 26

External cells differentiate into _________ and continue to divide and secrete fluid into the middle of the morula to create the ___________

Answer 26

trophoblasts blastocyst cavity.

Question 27

Internal cells are compacted into the_____________

Answer 27

inner | cell mass.

Question 28

As the blastocyst expands, the_______ degenerates, in preparation for ________________

Answer 28

zona pellucida | implantation

Question 29

The __________ keeps developing embryo from attaching to fallopian tube lining until it reaches the uterus.

Answer 29

zona pellucida

Question 30

Fertilization usually occurs in the ______________

Answer 30

lateral third of the fallopian tube.

Question 31

By day 3, the embryo is a compact ball of cells. By day 4, it contains about 60 cells and has reached the uterus. Fluid is secreted into the middle of the morula forming a _________

Answer 31

blastocyst.

Question 32

After the zona pellucida degenerates, trophoblast cells adhere to, and burrow into __________

Answer 32

the lining of the | uterus or endometrium.

Question 33

Trophoblast cells proliferate and form two layers:

Answer 33

one maintains cellular membranes around the embryo the other fuses into a multinucleated mass,that invades the uterine lining.

Question 34

the other fuses into a multinucleated mass ___________ that invades the uterine lining.

Answer 34

syncytium,

Question 35

After the blastocyst is deeply embedded in the uterine lining, “holes” form in the outer trophoblast layer and __________________

Answer 35

fill with maternal blood. Embryo is now in contact with its source of nourishment

Question 36

Placenta is derived from both

Answer 36

embryonic trophoblast and maternal endometrial cells.

Question 37

during the second week, inner cell mass grows and divides into 2 sheets of cells, forming a ________________

Answer 37

bilaminar disc.

Question 38

Inner cell mass segregates into 2 layers:

Answer 38

epiblast (upper germ layer illustrated in blue) and | hypoblast (lower germ layer in yellow).

Question 39

Extensions of these cell sheets form 2 fluid filled sacs:

Answer 39

epiblast forms the amniotic sac | hypoblast gives rise to the yolk sac.

Question 40

________________ is filled with amniotic fluid that protects embryo from physical injury.

Answer 40

Amniotic sac

Question 41

_____________ is not an important food source.

Answer 41

yolk sac

Question 42

In order for the bilaminar disc to transform into a 3-layer structure, a raised groove called the ___________ forms in the epiblast.

Answer 42

primitive streak

Question 43

The primitive streak ends in the ____________

Answer 43

primitive node.

Question 44

________________ Changing from a 2 to a 3-layered disc

Answer 44

Mesoderm formation

Question 45

Epiblast cells move inward at the primitive streak. Initially they displace the hypoblast and form_____________ ____________________________

Answer 45

endoderm but then they form the third germ layer, mesoderm.

Question 46

_____________ gives rise to sheets of tightly joined cells on outside of the body (skin).

Answer 46

Ectoderm

Question 47

_____________ gives rise to sheets of tightly joined cells inside the body (digestive & respiratory tracts).

Answer 47

Endoderm

Question 48

_____________ gives rise to everything else. Mesodermal cells migrate widely and give rise to tissues such as muscle and bone.

Answer 48

Mesoderm

Question 49

Epiblast cells invaginate at the primitive node and migrate anteriorly to form __________

Answer 49

dorsal mesoderm.

Question 50

_________________ forming at the large arrow will become the notochord, a transient structure found in the midline that divides the body into right and left halves.

Answer 50

Mesoderm

Question 51

____________ has an important developmental function - it induces the formation of the nervous system.

Answer 51

Notochord

Question 52

The primitive streak is later reduced to a strip of __________________

Answer 52

epidermis over the coccyx.

Question 53

______________ part of the embryonic disc corresponds to the top of the future head.

Answer 53

Dorsal-most

Question 54

Events by which the notochord induces ectoderm cells to form the nervous system are called ____________

Answer 54

neurolation

Question 55

Ectoderm in the dorsal midline thickens - called the ______________________

Answer 55

the neural plate.

Question 56

Edges of the neural plate begin to fold toward each other called the ___________

Answer 56

neural folds.

Question 57

Neural tube develops into ____________________

Answer 57

the | central nervous system (i.e., brain and spinal cord).

Question 58

Neural crest cells migrate | throughout the body developing_________________

Answer 58

into the peripheral nervous system.

Question 59

Ectoderm that will become ___________ is shown in dark blue -

Answer 59

neural crest

Question 60

Ectoderm that will become the__________ is shown in light blue -

Answer 60

neural tube

Question 61

Ectoderm that forms ____________ is shown in medium blue and forms the skin covering the spine

Answer 61

epidermis

Question 62

• The neural plate ____________ as the embryo grows. | •

Answer 62

enlarges dorsally

Question 63

The neural groove forms and neural | folds meet in the midline to form the ____________

Answer 63

neural tube. Somites (~40 pairs) are adjacent to neural tube.

Question 64

Neural tube closes first near the middle of the embryo and then proceeds both______________

Answer 64

rostrally and caudally.

Question 65

If closure is incomplete caudally, ,________________________ closure is incomplete rostrally___________________

Answer 65

the child is born with spinal bifida. , the brain will not develop.

Question 66

Animation shows how the embryo’s body changes from a flat disc into _____________

Answer 66

a 3-dimensional cylinder

Question 67

Main force responsible for embryo folding is differential growth of tissues - ____________

Answer 67

ectoderm expands more | than endoderm.

Question 68

Cross-section of an embryo illustrates the neural tube and derivatives of mesoderm: __________________

Answer 68

notochord, | somites, intermediate mesoderm and lateral mesoderm.

Question 69

The ectoderm grows more vigorously than yolk sac, becoming convex in shape. Ectoderm then grows together ventrally, forming the ventral midline of the body.

Answer 69

Middle stage ~ Day 25

Question 70

Ectoderm then | grows together ventrally, forming the _____________________

Answer 70

ventral midline of the body.

Question 71

The mesoderm differentiates – the medial part of the somite forms _________ whereas the lateral mesoderm divides into ________________

Answer 71

the sclerotome | somatic mesoderm and splanchnic mesoderm.

Question 72

Most of the yolk sac is folded inside the embryo, forming | •

Answer 72

the gut tube.

Question 73

Somites divide into 3 parts:

Answer 73

1) Sclerotome forms the vertebral column and ribs. 2) Myotome forms the limb and trunk muscles. 3) Dermatome gives rise to the dermis.

Question 74

___________ forms the vertebral column and ribs.

Answer 74

Sclerotome

Question 75

__________ forms the limb and trunk muscles.

Answer 75

Myotome

Question 76

____________ gives rise to the dermis.

Answer 76

Dermatome

Question 77

_______________ gives rise to kidneys and gonads.

Answer 77

Intermediate mesoderm

Question 78

_________________ forms membranes that surround viscera & gives rise to heart and blood vessels.

Answer 78

Splanchnic (visceral) mesoderm

Question 79

_________________forms membranes that line the body cavity. The coelom, or ventral body cavity, is surrounded by lateral mesoderm

Answer 79

- Somatic (body) mesoderm

Question 80

Animation that presents embryo folding from the

Answer 80

sagittal perspective Heart Development

Question 81

Condensations of mesoderm at the rostral end of the embryonic disc give rise to ____________

Answer 81

the heart.

Question 82

• Condensations form a pair of tubes that fuse,________________________

Answer 82

giving rise to the primitive heart tube.

Question 83

• Primitive heart tube folds up and twists around to form the ________________

Answer 83

four-chambered heart.

Question 84

• Embryonic heart is beating and pumping blood by _______________________

Answer 84

1 month in utero.

Question 85

Endoderm attached to the yolk sac folds inward, forming ___________________

Answer 85

the major divisions of the gut (foregut, | midgut, and hindgut).

Question 86

• Tissues derived from endoderm differentiate into

Answer 86

linings of respiratory, gastrointestinal, and | urogenital systems:

Question 87

___________ differentiates into the mouth, pharynx, esophagus, lung buds, stomach, and part of the small intestine.

Answer 87

Foregut

Question 88

__________ differentiates into the remainder of the small intestine and two-thirds of the large intestine.

Answer 88

Midgut

Question 89

____________ differentiates into the remainder of the large intestine, rectum and urogenital system.

Answer 89

Hindgut

Question 90

• There is a common pattern to all vertebrate development. | __________ forms skin and the nervous system.

Answer 90

- Ectoderm

Question 91

_______ forms connective tissue, blood cells, heart, bone, and muscle.

Answer 91

mesoderm

Question 92

______________ forms the lining of respiratory and digestive tubes.

Answer 92

Endoderm