Embryology/ Limb Development Flashcards Preview

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Flashcards in Embryology/ Limb Development Deck (32):
1

Embyonic Disk

Give rise to germ layers that form all the tissues and organs of the embryo

2

What gives the begining of morphogenesis

Gastrulation

3

Establishment of the body of the Cylindrical Embryo

Is a result of the folding of the flat trilaminar embryonic disk

4

What surrounds the secondary oocyte

Zona Pellucida and Corona Radiata

5

Cleavage

2 cell to 4 cell to 8 cells all happen in the uterine tube.
16-32 cells is classified as the morula

The morula enters the uterus considered a blastocyst

Blastocyst has inner cell mass called EMBRYOBLASTt and outer cell mass called TROPHOBLAST

6

When does implantation begin? Where does it occur?

It begins on the first week and ends on the second week. It implants on the posterior wall of the superior part as the zona pellucida dissapears

7

What does the trophoblast become?

1. Cytotrohpoblast
2. Syncytiotrohoblst
Note: #2 forms a blood filled lacunae that erodes the mothers endometrial blood vessels and establishes a uteroplacental circulation

8

What are two types of abnormal pregnancies

1. Ectopic Pregnancy
2. Placenta previa (implantation in the inferior segment of the uterus near the internal os) In this case patients would present with vaginal bleeding.

9

Second Week of Development (Bilaminar Germ Disc)

Period of 2's
1. Inner Cell Mass- becomes epiblast and hypoblast

2. Outer Cell Mass- becomes Cytotrophoblast and Synctiotrophoblast

3. Cavities form (2)- Amniotic Cavity and the Yolk sac cavity

4. Extraembryonic (Lateral) Mesoderm splits- Somatic Layer and Splanchnic Layer

10

Third Week of development (Trilaminar Germ Disc)

Period of Threes
1. Primitive Streak (Gastrulation gives us the Three Germ Layers)

2. Primitive Node ( Neuralation gives us the Neural Plate, Neural Groove, and Neural Tube)

3. Mesoderm on each side of the notochord (Paraxial gives us the intermediate mesoderm, the lateral plate mesoderm, and the neural crest cells

11

What structure gives rise to all three germ layers

Epiblast. It is called gastrulation

12

What structure gives the neural tube?

Ectoderm. It is called neuralation

13

What structure produces HCG

The Placenta

14

What two parts make up the placenta

The Villous Chorion (baby)
Decidua Basalis (Mom)

Note: There are three different types of Decidua

15

Which structure will regress by the fourth month of pregnancy?

Cytotrophoblast. As a result the exchange from mother to baby an baby to mother takes place across the synctiotrophoblst and fetal endothelium.

16

Umbilical Cord

Umbilical vessels = 2 arteries plus LEFT umbilical vein

Ducts = 2 Ducts Allantois plus virelline duct (both of which will be atrophied

17

When considering twins which structure must each baby have of it's own regardless of whether they are monozygotic or dyzygotic twins?

A. Placenta
B. Chorion
C. Amnion
D. Yolk Sac

Amnion

18

How many degrees is limb rotation

90 degrees

19

Amelia

absence of an entire limb

20

Meromelia

Absence of part of a limb

21

Phocomelia

Short, poorly formed limb

22

Polydactyly

Extra digit

23

Syndactyly

Fusion of digits

24

Lobster Claw Deformity

Middle digit is absent

25

How do limb buds elongate

By proliferation of the mesenchyme

26

Relationship between growth and rotation of limbs and cutaneous nerve supply.

Know that there is a relationship

27

When does the initial growth of limbs occur

4-8 weeks

28

Which limb buds develop first upper or lower

Upper by approximately 2 days

29

AER (Apical Ectodermal Ridge)

has an inductive influence on the limb mesenchyme which promotes growth and development of the limbs
(PROXIMODISTSAL AIXS)

30

How do limb buds elongate

By proliferation of the mesenchyme within them.

31

The limb grows in how many different axes

proximal- distal
dorsal-ventral
posterior-anterior

32

What genes and what signaling mechanisms are essential for the limb outgrowth carried out by AER?

FGF Signaling
HOX genes (retinoic acid and/or ethanol can effect the HOX genes)