Prenatal Development (5)* Flashcards
Prenatal development stages***
- Ovulation (9-16 days of the menstrual cycle)
- Fertilisation (24hrs after this)
- Male + female chromosome material unite (24-30hrs)
- Egg cell divides
- 2 cells (36hrs after fertilisation)
- 4 cells (48hrs after fertilisation)
- Cluster of 16-32 cells (3 days)
- Hollow ball of about 100 cells (4 days)
- Zygote enters the uterus (4-5 days)
- Zygote begins to attach to the wall of the uterus (6-7 days)
- Zygote is completely implanted in the uterine wall (12-14 days)
3 stages of prenatal development
Zygote (up to 2 weeks)
Embryo (2-8)
Foetal (from 2 months)
Zygote
A single cell embryo
How many chromosomes does an embryo contain
46
Heart appears
18 days after fertilisation
When are major features (such as hands, arms, fingers, eyes…) defined
8 weeks (end of embryo stage)
The brain and spinal chord… what stage
Embryo stage
Forebrain
Cerebral hemispheres, hypothalamus, thalamus
Midbrain
Superior + inferior colliculi, substancia nigra
Hindbrain
Medulla oblongata, pons
3 weeks…brain and spinal chord
Neural plate thickens first at the head and then folds into the neural tube which forms the brain and spinal chord
Movement
Even though mother typically doesn’t feel it for another 10 weeks, embryo starts moving at 5-6 weeks
XX
Female
XY
Male
6 months… unfolding in the cortex
- sulci + gyri
- increases surface area
- frontal, parietal + occipital lobes differentiated
Cerebral cells mature by..
27 weeks
Touch sensitive by…
13-14 weeks
Responds to growing medley of sounds
20 weeks
Respond to taste
25 weeks
Sweet substances in fluid…
Increase swallowing