Embryology - Principles

Question 1

From fertilisation to end of week three, what is the thing called?

Answer 1

Conceptus or embryo. Slide 5

Question 2

What is the term to describe the conceptus during weeks 4 to 8?

Answer 2

Embryo. Slide 5

Question 3

From week 9 till birth what is the embryo called?

Answer 3

Foetus. Slide 5

Question 4

What is gametogenesis?

Answer 4

Germ cell formation. Slide 7

Question 5

What is the formation of the oocyte and spermatoza called?

Answer 5

Oogenesis and spermatogenesis. Slide 7

Question 6

What is a zygote?

Answer 6

The fertilised oocyte. Slide 8

Question 7

What are corona radiate?

Answer 7

The support cells which surround the zona pellucida. Sperm cells are able to get through. Slide 8

Question 8

What is the acrosome?

Answer 8

It is the apex of the sperm head which contains enzymes to break the zona pellucida down. Slide 8

Question 9

What is cleavage?

Answer 9

Period of rapid cell division with no increase in size. Slide 9

Question 10

What is the fertilised egg called up to 16+ cells?

Answer 10

A morula. Slide 9

Question 11

In a blastocyst there are two different types of cells, what do they do?

Answer 11

One form a layer around the outer ring next to the zona pellucida and this makes the placenta. The other forms a small cluster of cells which is the inner cell mass. Slide 9

Question 12

What does totipotent mean?

Answer 12

Any specialisation of cell. Slide 9

Question 13

What are the 3 germ layers in an embryo?

Answer 13

Ectoderm, mesoderm and endoderm. Slide 10

Question 14

What will each germ layer do in the embryo?

Answer 14

Ectoderm gives rise to skin and the endoderm forms the gut tube. Slide 10

Question 15

What does embryonic folding mean?

Answer 15

Trying to make the embryo more 3D by folding and producing a “tube within a tube” where the gut tube is within a tube of skin. Slide 11

Question 16

What does organogenesis mean?

Answer 16

Formation of organs and organ systems. Slide 12

Question 17

What happens during the foetal period?

Answer 17

Growth and weight gain. Also the tissues become more mature and functional. Visible sexual differentiation and there are bones laid down so connections made in CNS. Slide 13

Question 18

Why is terminology and landmarks different to those used in adult anatomy?

Answer 18

A the baby’s positioning in anatomical position is different and more curved round. Slide 14

Question 19

What is the ventral part of the baby?

Answer 19

The anterior front part. Slide 14

Question 20

What is the dorsal part of the baby?

Answer 20

The posterior back part. Slide 14

Question 21

What are the primary processes of growing from embryo to foetus?

Answer 21

Cell division, differentiation, cell attachment, apoptosis, induction and cell migration. Slide 16+17

Question 22

What does the cell division contribute to in the primary process of growth in the embryo?

Answer 22

Increase in number of cells. Slide 16

Question 23

What does the differentiation contribute to in the primary process of growth in the embryo?

Answer 23

Specialisation, change in appearance and adoption of new functions. Slide 16

Question 24

What does the cell attachment contribute to in the primary process of growth in the embryo?

Answer 24

Physical/functional linkages and formation of tissues. Slide 16

Question 25

What does the apoptosis contribute to in the primary process of growth in the embryo?

Answer 25

Programmed cell dead when defining complex structures. Slide 16

Question 26

What does the induction contribute to in the primary process of growth in the embryo?

Answer 26

Creates the ability of one cell type to cause another to differentiate e.g. using a proteins which causes a cell to react to it. Slide 17

Question 27

What does the cell migration contribute to in the primary process of growth in the embryo?

Answer 27

Movement from one location to another. Slide 17

Question 28

What are the two secondary processes?

Answer 28

Axis formation and folding/rotation. Slide 18+19

Question 29

What does the axis formation contribute to in the secondary process of growth in the embryo?

Answer 29

Cells need to know where they are in relation to each other and the embryo as a whole. Slide 18

Question 30

What does the folding/rotation contribute to in the secondary process of growth in the embryo?

Answer 30

Creates the entire embryo or structures within it creating the 3D form, e.g. formation of the heart as it starts as a simple tube and then is folded and rotated. Slide 19

Question 31

How is development of the foetus controlled?

Answer 31

Genetically - gene expression and is tightly regulated.
Epigenetic - preferential expression of either maternal/paternal copy of a gene.
Environmental - however the foetus can’t really control how it responds to it. Slide 20

Question 32

What is epigenetic control?

Answer 32

Genetic imprinting where genes are preferentially expressed from either the maternal or paternal copy, if a copy is deleted which is preferred, then mutations come about. Slide 21