Embryology

Question 1

What percentage of birth defects are of known causes?

Answer 1

50%

Question 2

What is a teratogen? Teratology?

Answer 2

Teratogen: anything that causes a birth defect
Teratology: Science of understanding causes of birth defects.

Question 3

What are some known teratogens?

Answer 3

Alcohol, Thalidomide.

Question 4

What is pregenesis?

Answer 4

Developmental pre-conditions enabling successful reproduction.

Question 5

What are the steps of pregenesis/

Answer 5

1. Formation/migration of primordial germ cells
2. Cortico-medullary differentiation of gonads (ovaries and testes)
3. Increase cell number by mitosis
4. Gametogenesis

Question 6

Where do the primordial germ cell migrate to?

Answer 6

They go into the yolk sac for a period, then come back.

Question 7

What are teratomas?

Answer 7

Migrating cells that end up in the wrong places, like primordial germ cells.

Question 8

What is meiosis? What is different in the S phase of mitosis and meiosis?

Answer 8

Meiosis: cell division to generate gametes.

Mitosis S phase, sister chromatids line up. Meiosis S phase, homologous chromosomes line up.

Question 9

What is spermatogoina? Oogonia?

Answer 9

Spermatogonia: male primordial germ cell.
Oogonia: Female primordial germ cell

Question 10

What is meiotic nondisjunction?

Answer 10

Failure of paired chromosomes to separate regularly.

Question 11

What is surrounding the egg after follicle rupture? What does it do?

Answer 11

Sticky cumulus corona radiata. Gives nutrients and helps egg move.

Question 12

What is capacitiation?

Answer 12

Process which sperm cells undergo in order to reach and penetrate the egg.

Question 13

What are the barriers the sperm must penetrate?

Answer 13

Corona radiata, Zona Pellucida, Egg plasma membrane.

Question 14

Acrosome and Cortical reactions are based on what?

Answer 14

Acrosome=sperm

Cortical=egg

Question 15

Once fertilized the cell is now______ and termed ______.

Answer 15

Diploid, Zygote.

Question 16

What is cleavage?

Answer 16

Set of mitotic events where each daughter cell is half the size of the parent.

Question 17

If the zygote undergoes cleavage very early, what can result?

Answer 17

Twins.

Question 18

What is compaction?

Answer 18

The cleaved cells flatten and create junctions.

Question 19

What is a morula?

Answer 19

Solid ball of cells.

Question 20

What is a blasocyst? What is contained in it?

Answer 20

The zygote compacts and creates a hollow center. Inner cell mass and trophoblast.

Question 21

What is hatching?

Answer 21

Blastocyst escapes the zona pellucida so it can grow.

Question 22

What cells arise during the second week?

Answer 22

1. Trophoblast

2. Inner cell mass

Question 23

What cells arise from the trophoblast?

Answer 23

Cytotrophoblast, Syncytiotrophoblast.

Question 24

What cells arise from the inner cell mass and what do they form?

Answer 24

Epiblast: Amnion
Hypoblast: Yolk sac

Question 25

What happens during blastogenesis week 3?

Answer 25

Formations of 3 layers. Gastrulation.

Question 26

WHere is the primitive streak?

Answer 26

On the epiblast.

Question 27

Epiblast cells that migrate between the epiblast and hypoblast become?

Answer 27

Mesoderm

Question 28

Epiblast cells that migrate to the hypoblast?

Answer 28

Endoderm

Question 29

Epiblast cells that remain in the epiblast?

Answer 29

Ectoderm

Question 30

Ectoderm forms?

Answer 30

Epidermis, Nervous system, enamel.

Question 31

What does the mesoderm form?

Answer 31

Connective tissue, Muscle..

Question 32

What does the endoderm form?

Answer 32

Guts, respiratory system.

Question 33

What is important about the notochord?

Answer 33

A signaling machine made of mesoderm.

Question 34

What happens during week 4?

Answer 34

Neuralation. Neural plate folds to become neural tube.

Question 35

What is the neural plate?

Answer 35

Ectoderm induced to differentiate into neural tissue.

Question 36

what are the 3 types of mesoderm? What do they form?

Answer 36

1. Somites (paraxial): Muscle, Bone, Connective tissue 2. Lateral plate mesoderm: Muscle of body wall, Digestive tract, proximal part of limpts 3. Intermediate Mesoderm: Urinary and parts of genital system.

Question 37

What are the two types of Lateral plate mesoderm?

Answer 37

1. Splanchnic, associated with the endoderm. | 2. Somatic: Associated with the ectoderm.

Question 38

Transverse or lateral folding?

Answer 38

Left and right sides of the embryo curve towards the midline.

Question 39

Cephalocaudal Folding?

Answer 39

Occurs in head and tail regions.

Question 40

Explain the neural tube closure beginning to end.

Answer 40

1. Closure begins midway. 2. Anterior cranial neuropore closes Posterior caudal neuropore closes

Question 41

what are placodes?

Answer 41

Thickening of ectoderm from signaling of the | nervous system.

Question 42

What is the Stomadeam? Proctodeam? What is speacial about them?

Answer 42

Stomadeam=future mouth Proctodeam=Future anus Only have Ectoderm and endoderm.

Question 43

What is the Oropharangeal membrane? Proctodeal membrane?

Answer 43

Oro=Membrane that separates oral cavity from the throat. | Proc=Membrane at proctodeam.