Emryology and maldevelopement

Question 1

What are the cellular processes involved in embryological development and how do they differ from adult cells.

Answer 1

Proliferation, differentiation, reorganisation (chemotaxis) and apoptosis. Embryological cells can do the first three all at once and adult cells can only do one at a time.

Question 2

What is an example of all four cellular processes being required in one loaction?

Answer 2

Digits as they need to grow, organise, have different tissues and not be webbed.

Question 3

When and where does PID occur?

Answer 3

preimplantation developement occurs usually in the fallopian tubes over the first 6 days after fertilisation.

Question 4

What is the difference between a morla and a blastocyst?

Answer 4

A morla is just a ball of undifferentiated cells, a blastocyst has an outer layer of trophectoderm and an inner cell mass with a fluid filled cavity.

Question 5

What is gastrulation?

Answer 5

It is the way the bilayer disk in the implanted blastocyst becomes three layers at day 14-18.

Question 6

What are the three germ layers precursors of?

Answer 6

Endoderm = gut, liver and lungs
Mesoderm= skeleton, muscle, kidney, heart and blood.
Ectoderm = skin and nervous tissue.

Question 7

What structure controls neurilation?

Answer 7

The notochord in the mesoderm.

Question 8

When do the folds in the neural plate fuse?

Answer 8

Week 4

Question 9

What developmental things have occured in the embryo by week 4?

Answer 9

Initiation of villi development, all internal tissues have precursors, closed neural tube.

Question 10

When does an embryo become a fetus?

Answer 10

8 weeks as it is now clearly human.

Question 11

What cells form the neural plate

Answer 11

epiblasts

Question 12

What is role of the notch above the notocord?

Answer 12

It prevents proliferation above it.

Question 13

What are the stages of heart development?

Answer 13

Folding of the embryo, heart tube fusion, heart looping, separation and division of outflow tracts.

Question 14

When does the heart fuse to form one heart

Answer 14

day 21

Question 15

What two ducts are part of the fetal heart but are ligaments in the adult.

Answer 15

Ductus arteriosus- between pulmonary artery and aorta

Foramen ovale- between the two atria.

Question 16

What is the order of urogenital developmental stages?

Answer 16

Pronephros, mesonephros and then metanephros (by the 5th week)

Question 17

What does the ureteric bud give rise to?

Answer 17

Collecting duct, (in metanephric tissue) ureter, renal pelvis, major and minor calyces.

Question 18

Describe the development of the face.

Answer 18

The eyes start on the side of the head and then move medially. The side of the face develop separately and then join.

Question 19

When are the saccular and alveolar periods?

Answer 19

S= 26 weeks- birth

A=8 months to childhood

Question 20

What is the function of surfactant?

Answer 20

Reduce the surface tension in alveoli.

note produced by type 2 pneumocytes.

Question 21

What is the cause of respiratory distress syndrome?

Answer 21

Lack or absence of surfactant.

Question 22

what are the names of the ducts that form into genital and reproductive tracts (both genders)

Answer 22

Mesonephric and wolffian = male
paramesonephric and mullerian = female
Note both present until gender differentiation then opposite sex duct regress.

Question 23

What causes the differentiation of sex and when?

Answer 23

SRY at 7 week for males

lack of SRY at 9 weeks for females

Question 24

What do sertoli cells produce?

Answer 24

Anti-mullerian hormone.

Question 25

The upper 3rd of the uterus and superior genitalia in females is formed from the mullerian duct, what forms the lower two 3rds and lower genitalia?

Answer 25

The urogential sinus (lower vagina and bulbourethral glands)

Question 26

Which hormones support the development of the wolffian ducts?

Answer 26

Testosterone which is stimulated by HCG

Question 27

What causes spina bifida?

Answer 27

Failure of the closure of the neural tube inferiorly at the posterior neuropore. (folic acid defciency increases risk)

Question 28

What are the three types of spina bifida

Answer 28

Occulata, meningocele and myelomeningocele.

Question 29

What does failure of the anterior neurope cause ?

Answer 29

Anecephaly. (also due to folate deficiency).

Question 30

Name three things that can act as teratogens.

Answer 30

Thalidomide, cocain, alcohol , radiation, rubella virus, HSV, HIV and lithium.

Question 31

How did thalidomide cause malformations?

Answer 31

It interferes with blood vessel development and was given in the first trimester when the fetsu is most vunerable to teratogens. 8 weeks = morning sickness and limb development.
Note now used in cancer treatment.

Question 32

Why does transposition of great arteries (aorta connected to the right ventricle and Pulmonary artery connected to the left ventricle) only show cyanosis after birth?

Answer 32

In utero the foramen ovale and ductus arteriosus allow for free flow within the heart, but they close at birth meaning the blood supplies are closed off to eachother and the baby becomes cyanotic.