Embryology Flashcards
What stages of development are referred to by
conceptus
embryo
foetus?
conceptus - fertilization - week 3
embryo - weeks 4 - 8
foetus - week 9 - birth
What is gametogenesis?
Formation of germ cells:
oogenesis - oocyte
spematogenesis - spermatozoa
What triggers the formation of the zygote?
Fertilization
What is cleavage?
Period of rapid cell division forming first the morula and then the blastocyte
What is gastrulation?
Formation of germ layers:
ectoderm
mesoderm
endoderm
Establishment of body axes
What is morphogenesis?
Formation of the body plan - embryonic folding
What is organogensis?
Primordia of all organ systems
What occurs in the foetal period?
Growth and weight gain
Tissue maturation
Overt sexual differentiation
Bone laid done
Connection in CNS
What are the primary processes involved in development?
Cell division
Apoptosis
Differentiation
Cell attachment
Induction
Cell migration
What are the secondary processes of development?
Axis formation/polarity
Folding/rotation
Increase/decrease in mass/dimension
How is embryonic development controlled?
Genetic
Epigenetic (preferential expression of maternal or paternal copy of gene)
Environemnt
How does the sperm digest its way into the egg?
Acrosomal enzymes
Up to which stage are blastomeres thought to be totipotent?
Up to 8 cell stage.
Which structures are formed from the ectoderm?
Epidermis
Nervous system
Which structures are formed from the mesoderm?
Lining of gut tube
Lining of respiratory tract
What structures are formed from the paraxial mesoderm?
Axial skeleton
Parts of dermis
Skeletal muscle
What structures are formed from the intermediate mesoderm?
Urogenital systems
What structures are formed from the lateral plate mesoderm?
Somatic: lining of body wall, most of dermis, parts of limbs
Visceral: mesothelial covering of organs, cardiovascular system
What occurs during the 3rd month of development?
Face of foetus more human looking
Limbs lengthen
1º ossification centres in long bones and skull
External genitalia
What happens in the 4th and 5th months?
Rapid increase in length
What happens in the 6th month to birth?
Rapid increase in weight
What is the critical period for the development of the neural system?
Embryonic period
Foetal period (especially the first half)
What is the critical period of develoment for the heart?
Embryonic period (particularly the first half)
