Embryology

Question 1

Week 4

Answer 1

Heart begins to beat
Formation of limbs

Question 2

Week 5

Answer 2

Development of face, limbs, eye, kidney, umbilical cord
Separation of heart
Development of digestive organs
Facial cleft/ limb anomalies/ cardiac wall defects

Question 3

Week 6

Answer 3

Spontaneous embryonic movement
Development of ear

Question 4

Week 7

Answer 4

Formation of AV valves
Ossification begins
Embryo surrounded by amniotic sac
Skeletal/ cardiac valve defects/ cleft palate/ kidney anomalies

Question 5

Malformation

Answer 5

Morphological defect of an organ/ larger body region
Intrinsically abnormal development process
Mechanism unknown - can be due to anomalies in cell differentiation, migration, proliferation + death.

Question 6

Deformation

Answer 6

Abnormal shape/ body part due to mechanical forces.
Usually over prolonged period of time, can be reversed.

Question 7

Disruption

Answer 7

Morphological defect of an organ/ body part resulting from external breakdown or interference with normal development process.
E.g. infections, drugs, amniotic band rupture, hyperthermia, ionising radiation.

Question 8

Dysplasia

Answer 8

Abnormal organisation of cells in tissues + its morphological results
E.g. Marfan’s syndrome, congenital ectodermal dysplasia.

Question 9

Sequence

Answer 9

Cascade of events arising from single known or presumed structural defect

Question 10

Pierre Robin sequence

Answer 10

Jaw constraint - micrognathia - glossoptosis - U-shaped cleft palate

Question 11

Syndrome

Answer 11

multiple defects that occur together in a predictable way.
Thought to be pathogenetically related.

Question 12

Polytopic field defect

Answer 12

Multiple anomalies in same developmental region
Arises from disturbance of single developmental field.

Question 13

Association

Answer 13

Non-random, pathogenically unrelated, multiple defects. Need to be present in more than 2 individuals with statistically related symptoms.

Question 14

Embryology

Answer 14

Study of prenatal development of embryos + fetuses

Question 15

Embryogenesis

Answer 15

From fertilisation to end of week 8

Question 16

Fetal period

Answer 16

From week 9 to birth

Question 17

Teratology

Answer 17

Studies developmental anomalies, birth defects + their causes

Question 18

Teratogen

Answer 18

Any agent that causes an abnormality following fetal exposure during pregnancy

Question 19

Polytopic field

Answer 19

group of anomalies derived from the disturbance of a single developmental field

Question 20

Acheiria, apodia acheiropodia

Answer 20

Absence of hands, feet or both

Question 21

Adactyly

Answer 21

Absence of all digits on limb

Question 22

Amelia, ectromelia

Answer 22

Complete absence of one or more limbs

Question 23

Arachnodactyly

Answer 23

Elongated digits

Question 24

Brachydactyly

Answer 24

shortened digits

Question 25

Camptodactyly

Answer 25

Flexion contracture of finger which cannot be fully extended

Question 26

Clinodactyly

Answer 26

Curving of 5th finger towards 4th

Question 27

Hemimelia

Answer 27

Absence of pre or postaxial structures of a limb

Question 28

Meromelia

Answer 28

Absence of part of a limb

Question 29

Oligodactyly

Answer 29

Absence of any numbers of fingers or toes

Question 30

Phocomelia

Answer 30

Abence of proximal limb structures

Question 31

Polydactyly

Answer 31

Presence of extra digits or part of digits

Question 32

Slit hand/ foot

Answer 32

Absence of central components of hand or foot

Question 33

Syndactyly

Answer 33

Fusion of digits

Question 34

Syntosis

Answer 34

Fusion of bones or intervening soft tissue

Question 35

Triphalangeal thumb

Answer 35

thumb with 3 instead of 2 phalanges.