Lecture 1

Question 1

How long is the Embryonic Period?

Answer 1

First 8 weeks

Question 2

How long is the Fetal Period?

Answer 2

remaining 30 weeks

Question 3

The Human embryonic development takes an average of

Answer 3

38 weeks

Question 4

Oocyte is a ____ containing only _____

Answer 4

haploid cell, 1 copy of each chromosome

Question 5

Oocyte remains viable within the fallopian tube for approximately ___

Answer 5

12 hours

Question 6

The oocyte is surrounded by a plasma membrane, a thick extracellular matrix or ______
and additional layers of cells called ______

Answer 6

zona pellucida, the corona radiata.

Question 7

Sperm are _____

Answer 7

haploid cells and are attracted to the oocyte.

Question 8

Sperm ______ through these membranes to ____

Answer 8

enzymatically digest a pathway, fertilize the oocyte.

Question 9

It is critical that only ______ fertilizes the oocyte, and all others are inhibited by ______ induced by the _______ after the first sperm has entered.

Answer 9

one sperm, chemical changes, zona pellucida

Question 10

What contributes more cytoplasm

Answer 10

oocyte, it is bigger than the sperm

Question 11

What contributes more genetic material?

Answer 11

Equal, both oocyte and sperm have equal genetic material.

Question 12

How long does nuclear fusion take?

Answer 12

12 hours

Question 13

What happens as a result of nuclear fusion?

Answer 13

A single diploid cell is formed (called a zygote)

Question 14

What changes must occur in order for fertilization to lead to development

Answer 14

Meiosis II is completed,
protein synthesis is stimulated, the cytoplasm within the zygote segregates to produce a polarity, and
DNA replication begins.

Question 15

What is cleavage?

Answer 15

series of mitotic divisions by

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

Question 16

When does cleavage occur?

Answer 16

24h after fertilization

Question 17

What are blastomeres?

Answer 17

Cells formed by cleavage divisions

Question 18

What happens to the size of the embryo as cleavage keeps creating new divisions?

Answer 18

The diameter stays the same

Question 19

What is the 16-32 stage called for the embryo?

Answer 19

Morula

Question 20

Initially dividing cells are ____, but then become ______ .

Answer 20

round, compacted with junctions between them

Question 21

Embryo differentiates into ____ and ____

Answer 21

external and internal cells

Question 22

external cells will become _____

Answer 22

the embryonic contribution to the placenta

Question 23

Inside the sphere are a small number of internal cells that ____

Answer 23

give rise to the embryo

Question 24

External cells differentiate into ____ and continue to divide and secrete fluid into the
middle of the morula to create the ___

Answer 24

trophoblasts, blastocyst cavity

Question 25

Internal cells are compacted into the_____________

Answer 25

``` inner cell mass (ICM) ```

Question 26

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

Answer 26

zona pellucida | implantation

Question 27

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

Answer 27

zona pellucida

Question 28

Fertilization usually occurs in the ______________

Answer 28

lateral third of the fallopian tube

Question 29

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 29

blastocyst.

Question 30

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

Answer 30

the lining of the | uterus or endometrium.

Question 31

syncytium

Answer 31

a multinucleated mass that invades the uterine lining

Question 32

How is the placenta formed?

Answer 32

derived from both embryonic trophoblast and maternal endometrial cells

Question 33

What are the two layers the Inner cell mass separates in to?

Answer 33

epiblast (upper germ layer) | hypoblast (lower germ layer)

Question 34

What do the epiblast and hypoblast form into?

Answer 34

amniotic sac = epiblast | yolk sac = hypoblast

Question 35

What is the amniotic sac

Answer 35

filled with amniotic fluid that protects embryo from physical injury

Question 36

What is the yolk sac

Answer 36

not an important food source

Question 37

In order for the bilaminar disc to transform into a 3-layer structure, a raised groove called the ____ forms in the . The primitive streak ends in the ____

Answer 37

primitive streak epiblast primitive node

Question 38

• Epiblast cells move ___ at the primitive streak. Initially they displace the hypoblast and form endoderm but then they form the third germ layer, ______

Answer 38

inward | mesoderm

Question 39

Ectoderm gives rise to

Answer 39

sheets of tightly joined cells on outside of the body (skin). Also the brain, spinal cord, CNS.

Question 40

Endoderm gives rise to

Answer 40

sheets of tightly joined cells inside the body (digestive & respiratory tracts).

Question 41

Mesoderm gives rise to

Answer 41

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

Question 42

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

Answer 42

dorsal mesoderm

Question 43

notochord is?

Answer 43

a transient structure found in the | midline that divides the body into right and left halves

Question 44

Notochord has an important developmental function

Answer 44

induces the formation of the nervous | system

Question 45

The primitive streak is later reduced to

Answer 45

a strip of epidermis over the coccyx

Question 46

Dorsal-most part of the embryonic disc corresponds to

Answer 46

top of the future head.

Question 47

What is neuralation?

Answer 47

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

Question 48

What is the neural plate?

Answer 48

Ectoderm in the dorsal midline thickens

Question 49

How are neural folds made?

Answer 49

When the edges of the neural plate begin to fold toward each other

Question 50

How is the neural tube formed? | What does it develop into

Answer 50

Neural folds meet dorsally and overlay the ectoderm develops into the central nervous system (i.e., brain and spinal cord).

Question 51

Ectoderm that will become neural crest, what is the neural crest?

Answer 51

Neural crest cells migrate | throughout the body developing into the peripheral nervous system

Question 52

Ectoderm that forms epidermis, what is the epidermis?

Answer 52

forms the skin covering the spine.

Question 53

The neural plate _____ as the embryo grows

Answer 53

enlarges dorsally

Question 54

The neural groove forms and ___ meet in the midline to form the neural tube

Answer 54

neural folds

Question 55

Neural tube closes first ____ of the embryo and then proceeds ___

Answer 55

near the middle | both rostrally and caudally

Question 56

If closure is incomplete caudally, the child is born with

Answer 56

spinal bifida

Question 57

If closure is incomplete rostrally, ____

Answer 57

the brain will not develop

Question 58

Main force responsible for embryo folding is ______ - the ____ expands more than the ____

Answer 58

differential growth of tissues ectoderm endoderm

Question 59

The ____ grows more vigorously than yolk sac, becoming convex in shape. It then grows together ____, forming the ____ of the body.

Answer 59

ectoderm ventrally ventral midline

Question 60

the medial part of the somite forms the ____

Answer 60

sclerotome

Question 61

the lateral mesoderm divides into _____ and ______

Answer 61

somatic mesoderm and splanchnic mesoderm

Question 62

Most of the yolk sac is folded inside the embryo, forming the _____

Answer 62

gut tube

Question 63

Somites divide into 3 parts: Sclerotome forms the ____ Myotome forms the _____ Dermatome forms the _____

Answer 63

vertebral column and ribs. limb and trunk muscles. gives rise to the dermis.

Question 64

• Intermediate mesoderm gives rise to ____

Answer 64

kidneys and gonads.

Question 65

Splanchnic (visceral) mesoderm forms membranes that surround viscera & gives rise to ___

Answer 65

heart | and blood vessels.

Question 66

Somatic (body) mesoderm forms ___

Answer 66

membranes that line the body cavity

Question 67

Condensations of mesoderm at ___ of the embryonic disc give ___

Answer 67

rostral end, | rise to the heart

Question 68

Condensations form _____, giving rise to the

Answer 68

a pair of tubes that fuse | primitive heart tube

Question 69

Primitive heart tube folds up and twists around to form ____

Answer 69

four-chambered heart.

Question 70

Embryonic heart is

Answer 70

beating and pumping blood by 1 month in utero.

Question 71

Endoderm attached to the yolk sac folds____, forming the ___

Answer 71

inward, major divisions of the gut

Question 72

Tissues derived from endoderm differentiate into ____

Answer 72

linings of respiratory, gastrointestinal, and | urogenital systems

Question 73

Foregut differentiates into ___

Answer 73

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

Question 74

Midgut differentiates into ___

Answer 74

the remainder of the small intestine and two-thirds of the large intestine.

Question 75

Hindgut differentiates into ___

Answer 75

the remainder of the large intestine, rectum and urogenital system.

Question 76

Ectoderm forms

Answer 76

skin and the nervous system.

Question 77

Mesoderm forms

Answer 77

connective tissue, blood cells, heart, bone, and muscle

Question 78

Endoderm forms

Answer 78

the lining of respiratory and digestive tubes.