Embryology

Question 0

What is the ectoderm and give some examples of tissues that arise from it

Answer 0

Outermost of the 3 germ layers. Gives rise to skin, nervous system and the retina

Question 1

What is accretion?

Answer 1

An increase in cell size by gradual addition of smaller parts

Question 2

During what time is something defined as an embryo?

Answer 2

The organism between the first division of the zygote until 8 weeks

Question 3

What is the time period of a foetus?

Answer 3

An unborn verterbrae after the embryo stage (8 weeks), until birth

Question 4

What happens during gastrulation?

Answer 4

The morphology of the embryo is dramatically restructured by cell migration. This gives rise to the 3 germ layers

Question 5

What term refers to an increase in size due to an increase in cell size rather than division?

Answer 5

Hypertrophy

Question 6

What term refers to the process that controls the organised spatial distribution of cells that arise during embryonic development and give the shapes of tissues, organs, etc.?

Answer 6

Morphogenesis

Question 7

From what germ layer is the neural plate (and tube) derived?

Answer 7

Ectoderm.

Question 8

Where are neural crest cells derived from and what do they do?

Answer 8

Ectoderm. They migrate and generate many differentiated cell types

Question 9

What term refers to the formation of congenital malformations?

Answer 9

Teratogenesis

Question 10

What happens during neurulation?

Answer 10

The neural plate folds into the neural tube

Question 11

The first 8 weeks of development after fertilisation are the what period?

Answer 11

Embryonic

Question 12

What structures are already established by 8 weeks of development?

Answer 12

Fingers, toes, arms, legs, knees, elbows, ears, eyelids are unfused, tail disappears.
The internal systems are mostly complete but not yet functioning

Question 13

When are foetal movements usually first felt by the mother?

Answer 13

5th month of pregnancy -> foetus is ~15cm long by this time

Question 14

What is the average timing of pregnancy, both from fertilisation and LMP?

Answer 14

Fertilisation: average of 38 weeks
LMP: average of 40 weeks

Question 15

How would you calculate the expected date of delivery quickly?

Answer 15

date of LMP + 9 calendar months + 7 days

Question 16

40 clinical weeks of pregnancy refers to how many biological weeks?

Answer 16

38 weeks

Question 17

How do cells in the developing arm know if they are going to become part of a finger or the arm?

Answer 17

Pattern formation - there is a body plan and cells have positional knowledge due to 3 axes: proximo-distal, ventral-dorsal, medial-lateral

Question 18

What mechanisms does morphogenesis involve?

Answer 18

Cell migration and cell adhesion

Question 19

What is the time period from ovulation when fertilisation must occur?

Answer 19

Within 24 hours

Fertilisation can take 20-24 hours

Question 20

What is the definition of a zygote?

Answer 20

The initial cell formed from the joining of 2 gamete cells (ovum and spermatozoa)

Question 21

Once cleavage of the zygote starts and the zygote splits by mitosis, what is it referred as?

Answer 21

Blastomeres

Question 22

What is the term for a ball of cells/blastomeres?

Answer 22

A morula. At this stage the cells are communicating with each other

Question 23

What do the cells of the inner cell mass/embryoblast form?

Answer 23

The embryo

Question 24

What do the cells of the outer cell mass/trophoblast form?

Answer 24

The placenta and supporting structures

Question 25

What is the role of the zona pellucida?

Answer 25

To protect the zygote from more sperm

Question 26

When trophoblast cells begin pulling in fluid from the uterus, forming a cavity, what is the whole thing referred as? What is the cavity/cyst?

Answer 26

A blastocyst. | The cavity/cyst is a blastocoele

Question 27

How many days does it take the blastocyst to get to the uterus?

Answer 27

4-5 days

Question 28

In order to implant into the uterus what does the blastocyst have to do?

Answer 28

Squeeze out of the zona pellucida

Question 29

What is the decidual reaction?

Answer 29

When the endometrium reacts to the blastocyst

Question 30

What is the syncytiotrophoblast?

Answer 30

The epithelial covering of the embryonic placental villi which invades the wall of the uterus to establish nutrient circulation between foetus and mother

Question 31

What is the function of the primary yolk sac?

Answer 31

To provide the embryo with nutrients until the placenta has formed

Question 32

What produces hCG and when?

Answer 32

The syncytiotrophoblast by ~ day 14

Question 33

What does hCG do?

Answer 33

It maintains the corpus luteum, which maintains the endometrium

Question 34

What does the epiblast become?

Answer 34

The embryo

Question 35

What cell types derive from the mesoderm?

Answer 35

Muscle, connective tissue, cardiovascular system, blood cells, bone marrow, skeleton, reproductive organs

Question 36

What cell types derive from the endoderm?

Answer 36

Epithelia of respiratory and GI tract, glandular cells of GI-associated organs

Question 37

What is the cloaca?

Answer 37

Terminal part of the hindgut

Question 38

What organs/tissues derive from the foregut?

Answer 38

Pharynx, tongue, tonsils, salivary glands, upper resp system | Lower resp system, oesophagus, stomach, duodenum, liver, biliary apparatus, pancreas

Question 39

What organs derive from the midgut?

Answer 39

Small intestine, caecum, appendix, ascending colon, 2/3 of right transverse colon

Question 40

What organs derive from the hindgut?

Answer 40

1/3 of the left part of the transverse colon, descending colon, sigmoid colon, rectum, superior part of anal canal, urinary bladder and most of the urethra

Question 41

In simple terms - what organs derive from the hindgut?

Answer 41

Colon and below

Question 42

In simple terms - what organs derive from the midgut?

Answer 42

Small intestine to right transverse colon

Question 43

In simple terms - what organs derive from the foregut?

Answer 43

Pharynx to pancreas

Question 44

What 2 problems can occur to the oesophagus during development? How might they present?

Answer 44

Atresia (blockage) Stenosis (narrowing) Vomiting, usually contains bile and stomach contents. 20-30% with atresia also have Down's syndrome

Question 45

A newborn infant consistently projectile vomits after feeding, what is the likely problem?

Answer 45

Pyloric stenosis | Thickening of the pylorus, hypertrophied muscles, stomach distends with feeding. Contents expelled with force

Question 46

The septum transversum between the liver and the ventral abdominal wall becomes what?

Answer 46

The falciform ligament

Question 47

What is omphalocele?

Answer 47

Persistence of herniation within the umbilical cord

Question 48

What is gastroschisis?

Answer 48

Direct herniation into the amniotic cavity

Question 49

Name some pathologies that can occur with incorrect formation of the hindgut

Answer 49

Urorectal fistula Rectovaginal fistula Rectoperineal fistula Failure of anal membrane to breakdown

Question 50

The lungs begin as a bud off of what?

Answer 50

The gut tube

Question 51

The lungs are lined by epithelium derived from what germ layer?

Answer 51

Endoderm

Question 52

What does the epithelia of primitive alveoli thin and become?

Answer 52

Type I pneumocytes. Blood capillaries the start to invade this tissue

Question 53

By week 24 of development, what is limiting lung function? Can the lungs survive ex-utero at 24 weeks? If so, how?

Answer 53

Surface area and blood supply. The baby can survive and continue to develop ex-utero if there is intensive care: continuous positive airway pressure, oxygen and monitoring

Question 54

What do type II pneumocytes do?

Answer 54

Make surfactant -> this lowers the surface tension of water Stops the thin alveolar walls from sticking together

Question 55

Where can type I and II pneumocytes be found?

Answer 55

In alveoli

Question 56

What happens in respiratory distress syndrome?

Answer 56

There is not enough surfactant. Atelectasis happens -> lung collapse. The baby needs steroids, surfactant therapy, oxygen therapy and CPAP

Question 57

What might have gone wrong during lung development if pneumonia happens shortly after birth?

Answer 57

There might be an oesophageal fistula allowing fluid to enter the trachea.