Developmental: Lec. 4 - Prenatal Development

chapter 4

zygote age

fertilization - week 2

embryo age

week 2 - 10

foetus age

week 10 - birth

morula

**day 3**: ball of 16 cells, cell differentiation starts

Blastula

day 4-7: Cavity arises, embryo arises out of inner cells, implantation in uterus

Gastrulation

* week 2
* the formation of the 3 germ layers by migration and differentiation of blastula cells

Neurulation

* starts at week 3


* the formation of the neural plate, neural groove and neural tube from the ectoderm (the __outermost__ layer of cells or tissue of an embryo)

**Anencephaly**

\
* open skull
* closing of neural tube failed
* usually miscarriage or death shortly after birth

spina bifida

\
* open back
* closing of neural tube failed

when do we see the first primitive brain areas?

week 4

**Cranial-caudal**

head-tail

when do the eyes develop?

weel 4 - 8

development of the ear, what happens week 5 - 8?

**Week 5:** Groove (nr 14-18) \n **Week 6:** Instilling, start formation middle ear tube (nr 19-20) **Week 7-8:** Auricle, start formation eardrum (nr 21-23) \n **Week 8:** Inner ear; vestibulary system

when is organogenesis finished?

week 8

Which of the 5 senses develop first?

touch

what and when can the fetus start smelling?

* Everything in the amniotic fluid
* From 16 weeks

what can the fetus taste in the womb?

Blood of the mother with nutrients

how do we know the fetus can taste and smell in the womb?

* Taste and smell receptors have been developed
* Foetus swallows and breathes more after a meal from the mother
* Foetus makes faces after smoking by mother
* Baby has preference right after birth for smell of

1) food that mother has eaten often during pregnancy; \n 2) its own amniotic fluid

when does the optic nerve develop?

week 8 - 28

how much percent of children with mother addicted to alcohol get FAS (fetal alcohol syndrome)?

6%

microcephaly

small skull, limited brain growth, often in combination with intellectual disability and organ defects