Embryology

Question 1

sacrococcygeal teratoma

Answer 1

1 in 40,000 live births
if the primitive streak does not disappear completely, it can give rise to embryonic tumors containing cells from all three germ layers

Question 2

hESC

Answer 2

human embryonic stem cells
inner cell mass
retain their totipotency as they divide

Question 3

iPSCs

Answer 3

induced pluripotent cells

differentiated cells converted to pluripotent cells by forced expression of certain transcription factor genes

Question 4

neural tube

Answer 4

ectoderm

CNS

Question 5

neural crest

Answer 5

ectoderm
among most diversified cells in embryo
PNS
bones and cartilage of face and ears
pigment cells
tooth cores
adrenal medulla
septum between aorta and pulmonary trunk

Question 6

surface ectoderm

Answer 6

ectoderm

skin and associated organs (glands, hair, tooth enamel)

Question 7

axial mesoderm

Answer 7

notochord

Question 8

paraxial mesoderm

Answer 8

44 pairs of somites —> ribs, vertebra, dermis layer of skin, all skeletal muscles of tongue, back, body wall and limbs

Question 9

intermediate mesoderm

Answer 9

kidney, ureter, adrenal cortex, reproductive system

Question 10

lateral plate mesoderm

Answer 10

somatic (parietal): bone sof the limbs, and fat, blood vessels and CT of limbs and body wall, mesothelial lining of the outer body wall

splanchnic ( visceral):heart and splees, smooth muscle, CT of organs of the gut and cloaca, contributes to thymus, parathyroid, thyroid follicular cells

Question 11

NTDs

Answer 11

neural tube defects
when neural tube does not close properly
ectoderm

Question 12

anencephaly

Answer 12

NTD when failure of fusion at cranial end

ectoderm

Question 13

spina bifida

Answer 13

NTD when failure to fuse in the middle or caudal end

ectoderm

Question 14

ectodermal dysplasia

Answer 14

disruption of the normal development of surface ectodermal structures

Question 15

VACTERL

Answer 15

mesoderm
Vertebral malformations
Anal atresia (bladder and rectum not divided properly)
Cardiac defects
Tracheo-esophageal fistula
Renal abnormalities
Limb abnormalities

Question 16

neuroblastoma

Answer 16

neural crest

Neuroblastoma is a tumour derived from the peripheral nervous system and is the most common cancer diagnosed within the first year of life

Question 17

Treacher Collins Syndrome

Answer 17

neural crest defect - hypoplasia
ectodermTreacher Collins syndrome is a genetic disorder that most often affects the cheek bones, jaw, chin, and ears.
Symptoms include downward-slanting eyes, a very small jaw and chin, hearing loss, and vision loss. Some babies may be born with a hole in the roof of their mouth (cleft palate).
Treatment is focused on correcting facial structure, and can involve plastic surgery, orthodontics and dental care.

Question 18

Hirschsprung Disease

Answer 18

neural crest cells don’t migrate properly
This disorder is characterized by the absence of particular nerve cells (ganglions) in a segment of the bowel in an infant. The absence of ganglion cells causes the muscles in the bowels to lose their ability to move stool through the intestine (peristalsis).

Question 19

ectopia cordis

Answer 19

heart outside of chest

Question 20

gastroschesis

Answer 20

visceral organs lie outside of the body wall

Question 21

bladder extrophy

Answer 21

Bladder exstrophy is a complex, rare disorder that occurs early on while a fetus is developing in the womb. As the bladder is developing the abdominal wall does not fully form, leaving the pubic bones separated and the bladder exposed to the outside skin surface through an opening in the lower abdominal wall.

Question 22

critical period

Answer 22

the point at when morphological change is initiated or happening

Question 23

teratogens

Answer 23

an agent or factor which causes malformation of an embryo.

Question 24

agenesis

Answer 24

the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue.

Question 25

aplasia

Answer 25

the failure of an organ or tissue to develop or to function normally.

Question 26

hypoplasia

Answer 26

underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells

Question 27

malformation

Answer 27

a deformity; an abnormally formed part of the body

Question 28

Rule of 1s

Answer 28

Embryonic Week 1 yields:
1 embryonic structure: inner cell mass
1 fluid filled sac: blasocoel
1 placental precursor: trophoblast

Question 29

Rule of 2s

Answer 29

Embryonic Week 2 yields:
2 embryonic layers: epiblast and hypoblast
2 extra embryonic membranes: amniotic membrane and the primary yolk sac
2 placental cell types: cyto-trophoblast and the syncitio-trophoblast

Question 30

Rule of 3s

Answer 30

Embryonic Wek 3 yields:
3 germ layers: ectoderm, mesoderm. endoderm
3 extra embryonic layers:
3 “organs”: primitive streak, notochord, neural plate