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Flashcards in Life before birth Deck (20):
1

What are the 3 early developement stages before birth

Preimplantation, embryonic and foetal stage

2

What week does preimplantation occur

week 1

3

What weeks do embrhyonic stage occur

week 2-8

4

What weeks do foetal stages occur

week 9-38

5

Describe cleavage

mitotic division of fertilised oocyte, which allow passage down the narrowest part of the uterine tube. oocyte Is surrounded by tough glycoprotein coat to prevent embryo from implanting

6

Describe Blatocyte formation

ormed from morula. 2 population in blastocyst. Inner cell mass forms the embryo. The outside cells (trophectoderm) form placental structure. Differentiation occurs – inner cell mass form embryo and extraembryonic tissue. Outer cells form trophoblast (part of placenta)

7

Define gastrulation

The process of • Cell division and the migration of these dividing cells. Results in the formation of 3 germ layers.

8

Describe the formation of the germ layers

Oncde cells have invaginated. some displace the hypoblast creating the endoderm. Others lie between the epiblast and endoderm to form mesoderm. Remaining cells in the epiblast form the ectoderm

9

What does ectoderm go on to form

nervous system, tooth enamel, cornea and eye lens

10

What does endoderm go on to form

Liver, pancreas and thymus

11

What does mesoderm go on to form

Notochord, dermis, skeletal system

12

Name the 3 extra embryonic membranes

Amnion, yolk sac and chorion

13

What is the yolk ac continuous with

The hypoblast

14

When does the yolk sac dissapear

week 20

15

What is the yolk sac involved in

Nutrient tranfer in early weeks

16

What doe the chorion form

Foetal component of the placenta

17

When is the chorion seen

The chorionic cavity is seen in early pregnancy, it dissapears when the amnion appears

18

What is the amnion continuous with

The epiblast

19

What is the function of the amnion

Its cavity fills up with amniotic fluid to provide protection for the developing embryo

20

When does the amnion dissapear

It is present up until birth