Principles of Embryology

Question 1

Over what time period is the embryo present?

Answer 1

week 4 to 8

Question 2

Over what time period is the foetus present?

Answer 2

week 9 to birth

Question 3

Describe germ cell formation

Answer 3

oogenesis produces oocyte

spermatogenesis produces spermatoza

Question 4

Describe fertilisation

Answer 4

fusion of sperm and oocyte to form zygote

Question 5

What happens during cleavage

Answer 5

morula becomes blastocyst in a matter of 4 days

Question 6

What is gastrulation?

Answer 6

formation of germ layers (week 3) ectoderm, mesoderm, endoderm

Question 7

How does the body plan occur?

Answer 7

tube within a tube system - embryonic folding

Question 8

What are the 4 phases of embryo in order

Answer 8

gametogenesis, fertilisation, cleavage and then gastrulation

Question 9

What occurs during foetal period?

Answer 9

growth + weight gain, overt differentiation, tissue goes from mature to functional, bone laid down and connections made in CNS

Question 10

Name the primary processes of development

Answer 10

cell division, differentiation, attachment, apoptosis, induction and migration

Question 11

What is meant by induction?

Answer 11

one cell inducting another to migrate

Question 12

Name the 2 secondary processes

Answer 12

axis formation, folding + rotation

Question 13

How is development controlled

Answer 13

genetically through gene expression regulation and epigenetically through preferential expression of maternal or paternal genes