Prenatal Development Flashcards
What are the 3 stages of development?
- The germinal stage - 1st and 2nd week
- The embryonic stage - till week 8
- The fetal stage - till week 40
What occurs before birth?
All of development, need to look prenatally if want to focus on development
What happens in the germinal stage?
The nuclei of the egg and the sperm fuse to form a zygote
What happens to the zygote?
A series of cell division occurs
the zygote starts to divide at 12 hours by a process called cleavage, to form morula
the morula continues to divide to form a blastocyst (200-300 cells)
What happens when an egg encounters a sperm?
Fertilisation
What happens when the egg travels down the fallopian tube?
Cell division occurs
day 4 - morula
day 7 - blastocyst
When and where is the blastocyst implanted?
Day 7, on the uterus wall
When does the embryonic stage occur?
Once implantation in the uterus takes place
What is the most important time of our life?
The embryonic stage because gastrulation occurs
What is gastrulation?
Formation of the nervous system
Stages of gastrulation
- Initially have a flatt embryonic disk
- Uneven rate of cell development forms three layers - ectoderm, mesoderm, endoderm
- The ectoderm is important - forms more rapidly, eventually folds to become the nervous system
What is the main role of the embryonic disk?
Forming the neural tube - primitive brain
What doe the neural tube consist of?
Neural fold - like a zip, causing closure
Top becomes frontal lobe
Back becomes spinal cord
What happens to the primative brain?
Starts to differentiate and develop different areas - forebrain, midbrain, hindbrain
have the spinal cord all the way down
What happens to the brain when you approach birth?
It has a familiar surface to the human brain, consists of wrinkles (gyri) and swellings (sulci)
