Embryology

Question 1

Embryology

Answer 1

Transition of a fertilised egg to a new human baby

Question 2

Embryonic period

Answer 2

Week 1 - week 8

Question 3

Fertilisation

Answer 3

until week 3

Question 4

Embryo

Answer 4

week 4-8

Question 5

Foetus

Answer 5

week 9 - birth

Question 6

Stages of embryogenesis

Answer 6

1. Gametogenesis
2. Fertilisation
3. Cleavage
4. Gastrulation
5. Morphogenesis
6. Organogenesis
7. Foetal period

Question 7

Gametogenesis

Answer 7

Germ cell formation
Oogenesis to oocyte
Spermatogenesis to spermatazoa

Question 8

Fertilisation

Answer 8

fusion of oocyte and spermatazoa to form a zygote

Question 9

Cleavage

Answer 9

Rapid cell division

Formation of morula then blastocyst

Question 10

Gastrulation

Answer 10

Formation of germ layers
Ectoderm, mesoderm, endoderm
Body axis established

Question 11

Morphogenesis

Answer 11

Formation of body plan
Embryonic folding (tube within a tube)

Question 12

Organogenesis

Answer 12

Formations of organs and organs systems

Question 13

Foetal period

Answer 13

Growth and weight gain
Tissues mature and become functional
Sexual differentiation
Bone laid down, connections in CNS

Question 14

Primary Processes

Answer 14

Cell division
Differentiation
Cell attachment
Apoptosis
Induction
Cell migration

Question 15

Secondary Processes

Answer 15

Axis/Polarity

Folding/Rotation

Question 16

Control of development

Answer 16

Genetic

Epigenetic

Question 17

Fertilisation Process

Answer 17

1. Sperm binds to zona pellucida glycoprotein
2. Acrosomal enzymes released from sperm head digest way into egg
3. Sperm and egg membrane fuse, sperm contents released into egg
4. Sperm entry trigger:
   - trigger of meiosis 2
   - release of cortical granules by oocyte

Question 18

Cleavage

Answer 18

Zygote undergoes mitotic divisions

Forms blastomeres

Question 19

Totipotent blastomeres

Answer 19

up to 8 cell stage

Question 20

Compaction

Answer 20

Cells confined within zona pellucida
Maximise available space by coming closer together
Form cell junctions
Outer cells form extensive gap junctions
Fluid enters through ZP

Question 21

Abnormal sites of implantation

Answer 21

Ovary, ampulla, uterine tube, lower part of uterus, cervix, peritoneum

Question 22

Implantation

Answer 22

Embryo divides into epiblast and hypoblast

Amniotic cavity begins to form

Question 23

Day 9

Answer 23

implantation complete

Question 24

Day 12

Answer 24

Chorionic cavity begins to form within extraembryonic mesoderm

Question 25

Day 13

Answer 25

Definitive yolk sac forms

Question 26

Primitive streak

Answer 26

Appears in midline of epiblast at end of week 2
Looks like scratch on surface
Ready for gastrulation

Question 27

Formation of germ layers

Answer 27

Gastrulation
2 layers become 3
Cells migrate through primitive streak

Question 28

Fate of ectoderm

Answer 28

Skin

Nervous system

Question 29

Fate of paraxial mesoderm

Answer 29

axial skeleton, voluntary muscle

Question 30

fate of intermediate mesoderm

Answer 30

Urogenital system

Question 31

Fate of lateral plate mesoderm (somatic part)

Answer 31

lining of body wall, limbs

Question 32

Fate of lateral plate mesoderm (visceral)

Answer 32

Cardiovascular system, organ covering, smooth muscle

Question 33

Fate of endoderm

Answer 33

Lining of gut tube
Lining of resp tact
lining of bladder and urethra