Embryology Unit 14

Front 1

What forms between the trophoblast cells and the inner cell mass?

Back 1

Endoderm

Front 2

The endoderm will form the _______ _____ ____ until it folds and becomes two parts.

Back 2

primary yolk sac

Front 3

What two parts form from the endoderm?

Back 3

primary yolk sac and secondary yolk sac

Front 4

Cells inside the trophoblasts begin to ________ and form ________ that will cause the primary sac to _________ and the secondary sac to be ________ to a small area near the inner cell mass.

Back 4

proliferate, mesoderm, disappear, confined

Front 5

Inner cell mass cells secrete fluid to form the _______ _______.

Back 5

amniotic cavity

Front 6

What arises on the floor of the amniotic cavity?

Back 6

Ectoderm

Front 7

In the amniotic cavity, inner cell mass now becomes the ________ _____.

Back 7

embryonic disc

Front 8

In the amniotic cavity the membrane becomes continuous with the _____ ___.

Back 8

yolk sac

Front 9

A cavity forms in the extraembryonic mesoderm called the _______ ______.

Back 9

chronic cavity

Front 10

What are fingerlike processes that extend out from the blastocyst during proliferation of the trophoblast cells?

Back 10

Villi

Front 11

The villi turn into ______ _____ when the mesoderm invades them.

Back 11

chorionic villi

Front 12

What is the area where some of the villi around the inner mass cell continue to develop?

Back 12

Chroion frondosum

Front 13

What does the chorion frondosum form?

Back 13

the fetal portion of the placenta

Front 14

Mesoderm extends from the chorion frondosum to the embryonic disc by means of the ______ _____.

Back 14

body stalk

Front 15

The embryonic disc is a layer of ________ and _______.

Back 15

ectoderm and endoderm

Front 16

The ectoderm cells proliferate and form the _______ ______.

Back 16

primitive streak

Front 17

The primitive streak is capable of forming new ectoderm and endoderm but also ___________ _________.

Back 17

intraembryonic mesoderm

Front 18

What is produced at the cephalic end of the primitive streak?

Back 18

Hensen's (prmitive) node

Front 19

In Hensen's node, a strip of cells grows in between the _______ and _______.

Back 19

ectoderm and endoderm

Front 20

What is the primitive axial skeleton?

Back 20

Notochord

Front 21

What is the area where the ecto and endoderm are so closely attached?

Back 21

prochordal plate

Front 22

What does the prochordal plate form?

Back 22

buccopharyngeal membrane

Front 23

As the intraembryonic mesoderm continues to grow, it meets up with the _________ _________.

Back 23

extraembryonic mesoderm

Front 24

During the development of the neural tube, the ectoderm cells immediately above the notochord thicken and become the ________ ______.

Back 24

neural plate

Front 25

The lateral edges of the neural plate grow upward and form the _______ _____.

Back 25

neural folds

Front 26

In between the neural folds is the ______ ______.

Back 26

neural groove

Front 27

The neural plate continues to grow until the two edges meet and form the ______ ______.

Back 27

neural tube

Front 28

The neural tube gives rise to the entire ______.

Back 28

CNS

Front 29

Development of somites begins around the ______ week.

Back 29

3rd

Front 30

Mesoderm around the notochord and neural tube forms blocks of tissue called ________.

Back 30

somites

Front 31

Somites begin at the _______ end of the embryo and progress __________. They are on both sides of the _________.

Back 31

cranial, caudally, midline

Front 32

Somites resemble the _______ ______.

Back 32

vertebral column

Front 33

Somites appear about the _____ day.

Back 33

16th

Front 34

By the 4th week, there are about _____ pairs of somites. What are they?

Back 34

30
3 occipital
8 cervical
12 thoracic
5 lumbar
5-8 coccygeal

Front 35

Somites are very significant and ultimately give rise to what?

Back 35

All the connective, muscular, and dermal tissue of the body with the exclusion of the head region.

Front 36

What 3 groups does somite tissue become differentiated into?

Back 36

Sclerotome
Myotome
Dermotome

Front 37

What is the innermost (medial) part of a somite?

Back 37

Sclerotome

Front 38

These cells migrate around the notochord and neural tube.

Back 38

Sclerotome

Front 39

Sclerotome will differentiate into what three parts?

Back 39

individual vertebrae
intervertebral discs
ribs

Front 40

What part of the somite is lateral to the sclerotome?

Back 40

Myotome (myomere)

Front 41

They myotome tissue differentiates into what?

Back 41

musculature of the trunk

Front 42

Innervation of the musculature of the trunk begins ______ and wherever the muscle may _____ the nerve will _____ with it.

Back 42

early, move, move

Front 43

What is the most lateral part of a somite?

Back 43

dermatome

Front 44

The dermatome tissue will differentiate into what 2 parts?

Back 44

dermis
some musculature

Front 45

When does flexion of the embryo begin?

Back 45

the end of the 3rd week

Front 46

Rapid growth causes the embryo to ______ resulting in a series of _____.

Back 46

buckle, folds

Front 47

What is rapid growth of the cephalic end that will become the head?

Back 47

cephalic fold

Front 48

During the flexion of the embryo the _______ area and the ________ membrane are now ______ to the neural plate.

Back 48

procardiac, buccopharyngeal, ventral

Front 49

While the embryo is flexing in a _______ plane, the lateral margins are also ________ so that the embryo is _________.

Back 49

sagittal, flexing, cylindrical

Front 50

During flexion of the embryo, the _____ _____ is brought up into the embryo creating the ________ _____.

Back 50

yolk sac, primitive gut