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Flashcards in Embryology Deck (69)
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1

What structure comes before blastocyst

Morula- a ball of undifferentiated cells within zona pellucida

2

Development from morula to blastocyst

Morula differentiates so inner cells differ from outer ones

3

Structure of blastocyst

Outer layer of trophectoderm with an inner cell mass and fluid filled cavity

4

When does blastocyst hatch from zona pellucida

6 days post fertilisation

5

What happens between day 6 to 10

Inner cells mass of blastocyst becomes bilayer disk made of hypoblast and epiblast cells

6

What is first change to bilayer disk of blastocyst

Gastrulation

7

What happens in gastrulation

Conversion of hypoblast and epiblast cells to 3 layers of germ cells

8

What are 3 layers of germ cells

Ectoderm
Mesoderm
Endoderm

9

Summarise gastrulation

Proliferation of epiblast cells into space between epiblast and hypoblasts cells which becomes endoderm cells. Then get apoptosis of hypoblast cells

10

What does ectoderm give rise to

Skin and nervous tissue

11

What does mesoderm give rise to

Muscles, blood, skeleton, heart and kidney

12

What does endoderm give rise to

Gut and lungs

13

What happens before end of gastrulation

Neurulation begins- differentiation of ectoderm to generate CNS

14

What controls neurulation

Notochord in mesoderm

15

What happens in junction with neurulation

Precursors of other tissues develop within embryo as it is converted from flattened tissue to 3D

16

What has happened by week 4

Precursors of all internal tissues have been laid and some external structures have begun to develop

17

Name given to extra digit

Polydactyly

18

What has happened to limbs by week 8

Limbs roate to definitive orientation resulting in helical pattern of lower extremity dermatomes

19

Link between thalidomide and limb deformties

Thalidomide was given to treat morning sickness. Morning sickness normally starts around 6 weeks which matches the main stages of limb development

20

How did thalidomide affect developing limbs

It damaged the developing blood vessels which were supplying them with the nutrients required for proper growth and development.

21

3 stages to kidney development

Pronephros-most immature form
Mesonephros- intermediate phase
Metanephros- most developed and persists as adult kidney

22

Where do gonads arise from

Intermediate mesoderm within urogenital ridges of embryo

23

Where do male genital ducts arise from

Mesonpehric ducts

24

Where do female genital ducts aruse from

Paramesonephric ducts

25

What determines differential development of male reproductive system

SRY on Y chromosome

26

Describe movement of kidney during its development

Ascends from near to bladder- ureters extend at same time as kidney ascends to maintain connections

27

Describe changes in vascular supply of kidney during development

Forms new connection with developing arterial system as it moves upwards- renal arteries are broken and reformed

28

Common kidney development abnormalities

One kidney may be retained in the pelvis
Retention of an artery may obstruct the ureter
Kidneys form seperately but then fuse to form horsehoe kidney

29

What covers gonad precursor

Colemic epithelial cells

30

What gives rise to gametes within gonads

Primordial germ cells