1: Principles of embryology Flashcards
When is the embryonic period of development?
First 8 weeks
How long, on average, is the gestation period of an embryo?
9/10 months
When is a fertilised egg refered to as a conceptus?
From FERTILISATION to the end of WEEK 3
During which weeks is a developing human called an embryo?
Week 4 to Week 8
From which point onwards is a developing human called a foetus?
Week 9
What is embryogenesis?
Formation and development of an embryo
What is oogenesis?
Formation of oocytes (egg cells)
What is spermatogenesis?
Formation of spermatozoa (sperm cells)
What happens during fertilisation?
The sperm and oocyte fuse to form a zygote
What is a zygote?
Single-celled embryo
formed during fertilisation.
What happens during cleavage?
Rapid increase in cell number
Does the overall size of the embryo increase during cleavage?
No
Gastrulation involves the formation of the ___ ___.
germ layers
What are the three germ layers formed during gastrulation?
Where are they relative to one another?
Ectoderm - outer layer
Mesoderm - middle layer
Endoderm - inner layer
ENDODERM is iNside
What happens after gastrulation in embryogenesis?
Embryonic folding
An embryo can be described as a tube within a tube. Which tube is found within the embryo and folds after gastrulation?
Gut tube
What occurs after embryogenesis?
Organogenesis
formation of organs and organ systems.
Which period starts at the end of the embryonic period?
Foetal period
What happens to the foetus’ weight during the foetal period?
Weight increases
What is the embryological equivalent of superior?
Cranial
What is the embryological equivalent of inferior?
Caudal
What is the embryological equivalent of anterior?
Ventral
What is the embryological equivalent of posterior?
Dorsal
What developmental process involves an increase in cell number?
Mitosis
What developmental process involves a cell gaining a new structure to suit its function?
Differentiation
Which developmental process involves programmed cell death?
Apoptosis
Which developmental process involves cells ordering other cells to differentiate?
Induction
During development, cells ___ from one area to another.
migrate
Development is controlled by ___ and the environment.
genetics
