Embryology and human development

Question 1

Most development takes place in the first 45 days. True or false?

Answer 1

True

Question 2

What are the six main stages of embryonic development?

Answer 2

Cleavage
Blastula
Gastrulation
Neuralation
Organogenesis
Enlargement

Question 3

What does the animal:vegetal pole determine?

Answer 3

the future anterior:posterior axis

Question 4

The anterior:posterior axis is determined by the oocyte. True or false?

Answer 4

True

Question 5

What is the dorso-ventral axis determined by?

Answer 5

The point of sperm entry

Question 6

What causes the rotation of the cortical cytoplasm?

Answer 6

the entry of sperm

Question 7

the proximal distal axis is important in limb formation. True or false?

Answer 7

True

Question 8

What is removed from the woman’s ovaries in IVF?

Answer 8

ova

Question 9

Which techniques are routinely used in IVF?

Answer 9

ovarian hyperstimulation to produce multiple eggs
ultrasound-guided transvaginal oocyte retrieval from ovaries
egg and sperm preparation
culture and selection of embryos before transfer into the uterus at approx 3-5 days after fertilisation

Question 10

At what developmental stage is IVF carried out?

Answer 10

late cleavage to early blastocyst formation

Question 11

The blastula is a hollow ball of cells. True or false?

Answer 11

True

Question 12

How does the blastocoel develop?

Answer 12

develops at the 16 cell stage via the action of Na+ pumps and osmosis

Question 13

What is a blastula?

Answer 13

A hollow ball of cells held together at the surface by tight junctions to form an epithelium

Question 14

In the formation of the gastrula, the single layered blastula becomes a __________ gastrula

Answer 14

3 layered

Question 15

What marks the point of invagination?

Answer 15

blastopore

Question 16

What are the 3 layers of gastrula?

Answer 16

ectoderm
mesoderm
endoderm

Question 17

How is the neural tube formed?

Answer 17

an infolding of the ectodermal layer along the dorsal surface of the developing embryo

Question 18

What is spina bifida?

Answer 18

a developmental disorder caused by the incomplete closing of the neural tube

Question 19

The incidence of spina bifida can be decreased by 70%. How can this be done?

Answer 19

The mother takes folic acid supplements prior to conception

Question 20

What is the precursor for the backbone?

Answer 20

The notochord

Question 21

What is the role of the ectoderm?

Answer 21

Gives rise to the skin, nervous system and sense organs

Question 22

What is the role of the mesoderm?

Answer 22

Gives rise to the connective tissues e.g. heart, skeleton, urogenital system

Question 23

What is the role of the endoderm?

Answer 23

Gives rise to the gut and associated organs e.g. lungs, liver, pancreas

Question 24

Is the embryonic body plan initially male or female?

Answer 24

Female and if the genes on the Y chromosome are expressed, the foetus develops into a male

Question 25

Which gene co-ordinates the changes between female to male?

Answer 25

SRY (Sex determining Region Y)

Question 26

At around 5-6 weeks of development, the cells of the primordial gonads are in a bipotential state. What does this mean?

Answer 26

They can become either male or female cells. SRY initiates testis differentiation by activating male-specific transcription factors that allow the ovarian cells to differentiate into testes

Question 27

What are corresponding parts in a male and female called?

Answer 27

homologous

Question 28

At how many weeks is an organism referred to as a foetus?

Answer 28

14