Resp. Embryology

Question 1

Describe the process of fertilisation

Answer 1

Pronuclei of gametes form on diploid cell called a zygote

Question 2

What does the zygote develop into?

Answer 2

A solid ball of cells (morula) and then into a blastocyst

Question 3

Which parent passes on mitochondrial diseases?

Answer 3

Mother

Question 4

What does Leber’s Hereditary Optic Neuropathy cause?

Answer 4

Blindness

Question 5

Why does the morula develop into a blastocyst?

Answer 5

Too large for distribution of nutrients via diffusion

Question 6

Where is pre-embryonic material at the stage of being a zygote, morula and blastocysts respectively?

Answer 6

Zygote - Fallopian tube

Morula and blastocyst - Uterine cavity

Question 7

What structures are required to transport the morula through the Fallopian tube? How can malfunction of these structures cause pathology?

Answer 7

Healthy ciliated epithelia

Malfunction can cause ectopic pregnancy

Question 8

What layer of the uterus is deep to the endometrium?

Answer 8

Myometrium

Question 9

What happens to the zygote after its formed?

Answer 9

Divides to form the zygote, moves through uterine tube to uterine cavity

Question 10

Describe the structure of the blastocyst

Answer 10

• Cells accumulated at one end - called an inner mass

- The outer lining of cells is called the trophoblast

Question 11

What cells does gametes arise from?

Answer 11

Spermatogonium and oogonium

Question 12

What layer of the uterus does the blastocyst implant into?

Answer 12

Endometrium

Question 13

How does the formation of the chorion arise?

Answer 13

The trophoblast of the blastocysts divides several times to form the chorion

Question 14

What are the different kind of twins that occur? What are the developmental differences?

Answer 14

Fraternal (dizygotic) and identical (monozygotic)

Question 15

What structure plats a key role in implantation?

Answer 15

Chorion - the outermost surrounding membrane of the blastocyst

Question 16

Describe the formation of the three germ layers

Answer 16

Epiblastic cells migrate into space between hypoblast and epiblast - forms trilaminar disc

Question 17

From what germ layer does the notochord arise?

Answer 17

Ectoderm

Question 18

How long does it take for the placenta to mature?

Answer 18

18-20 weeks

Question 19

What four things occur during the third week of pregnancy?

Answer 19

Gastrulation, neurulation, development of somites and early development of the CV system

Question 20

How does the lateral plate mesoderm further divide?

Answer 20

Into the somatic and splanchnic mesoderm

Question 21

What is the space between the splanchnic and somatic mesoderm called?

Answer 21

Intra-embryonic coelom

Question 22

What induces the ectoderm to form a neural tube?

Answer 22

Notochord - neural plate aides from ectoderm and sinks down to form neural tube

Question 23

What feature of the epiblast determines the axis of the embryo?

Answer 23

The primitive streak (invagination of the epiblast layer of cells)

Question 24

What is teratology?

Answer 24

The study of when things go wrong during development

Question 25

What is the cause of 60% of all developmental abnormalities?

Answer 25

Unknown causes

Question 26

What do each parts of the mesoderm develop into?

Answer 26

Paraxial mesoderm - somites Intermediate - urogenital system Lateral plate - body coverings and cavities

Question 27

Approx. at what day of pregnancy does implantation occur?

Answer 27

7

Question 28

What genetic factors can cause developmental issues?

Answer 28

Too many/few chromosomes Structural changes

Question 29

What does the real tube induce?

Answer 29

Thickening and segmentation of the mesoderm

Question 30

What infectious agents can transfer through the placenta?

Answer 30

ToRCH Toxoplasma, Rubella, Cytomegalovirus and Herpes

Question 31

After the process of gastrulation, what happens?

Answer 31

Folding of embryo (lateral)

Question 32

The inner cell mass of the blastocyst splits into two layers called what? What is their function?

Answer 32

Bilaminar disc - epiblast and hypoblast Separate amniotic and yolk sac

Question 33

Describe the genetics of gametes?

Answer 33

Genetically distinct

Question 34

What are the three functions of the placenta?

Answer 34

- Foetal nutrition - Transport of waste and gas - Immune etc

Question 35

What does the chorion do?

Answer 35

- Implantation - Forms part of the placenta - Secretes HCG

Question 36

How does the paraxial mesoderm differentiate?

Answer 36

Into dermatomes, myotomes and sclerotomes

Question 37

How is the diagnosis of malformations aided?

Answer 37

Prenantal and postnatal test - Blood AFP - Ultrasound (12 week anomaly) - Invasive tests (chorionic villus sampling and amniocentesis) - Hip stability - Testes - Fingers and toes - Hearing

Question 38

What environmental factors can effect development?

Answer 38

Drugs Alcohol/tobacco Infectious agents Others including radiation etc.

Question 39

What is the purpose of HCG?

Answer 39

Maintains endometrium

Question 40

What are the key features of the second week of pregnancy?

Answer 40

- Implantation or morula and endometrial wall - Cells from embryo form bilaminar disc - Sacs, membranes nd cord to nourish human conceptus form

Question 41

What three parts does the mesoderm split into?

Answer 41

Paraxial, intermediate and lateral plates

Question 42

What are the three periods of human development in the womb?

Answer 42

- Pre-embryonic (weeks 0-30 - Embryonic (weeks 4-8) - Foetal (weeks 9-40)

Question 43

How is the parietal pleura formed?

Answer 43

From somatic mesoderm

Question 44

What are the five stages of lung differentiation?

Answer 44

- Embryonic - Pseudoglandular - Canalicular - Saccular - Alveolar

Question 45

What forms from the septum transverse?

Answer 45

Tendinous part of the diaphragm

Question 46

What is formed from the two pleuroperitoneal membranes and peripheral body wall muscle?

Answer 46

Muscular part of the diaphragm

Question 47

What process occurs in the third week of development and gives rise to primitive gut tube?

Answer 47

Folding of embryo; gut tube formed from endoderm

Question 48

What is tracheosophageal fistula and atresia?

Answer 48

Fistula - abnormal or surgical made passage Atresia - a condition in which an orifice is pathologically closed or absent

Question 49

Where is the septum transverse initially located in the embryo?

Answer 49

Opposite somites C3-5 and then migrates caudally

Question 50

When the septum transverse migrates caudally what structures does it bring with it?

Answer 50

Spinal nerves C3, 4 and 5

Question 51

Where does a Bochdalek hernia occur?

Answer 51

Poseriolaterally on the diaphragm

Question 52

Where does a Morgagni hernia occur?

Answer 52

Anteriorly on the abdominal diaphragm

Question 53

What types of hiatal hernia are there?

Answer 53

Rolling (paraesophageal) and sliding

Question 54

What forms from the mesentery of the oesophagus?

Answer 54

The crura of the diaphragm

Question 55

The lung buds penetrate into which mesoderm? What does the mesoderm then turn into?

Answer 55

Visceral splanchnic mesoderm; visceral pleura

Question 56

At what week does the diverticulum (laryngotracheal groove) appear?

Answer 56

4th