Lecture 3: Animal Models in Research

Question 1

In vitro techniques are experiment procedure

Answer 1

carried out within the confines of a test tube/flask/plate.

Question 2

In vivo experimental technique is carried out…

Answer 2

within an organism

In vivo techniques are much more expensive and involve the use of laboratory animals

Question 3

Advantages & Disadvantages of In Vitro

Answer 3

In vitro has a reduced cost, allows the tight control of the physico-chemical environment and have reduced animal use.

They are however often difficult to replicate the conditions cells encounter in a living organism.

Systemic effects can also not be tested in this case.

Question 4

This means both approaches (In Vitro & In Vivo) are complimentary to each other with a test often first performed

Answer 4

in vitro before being reproduced in vivo

Question 5

A model organism for in vivo experiment would be…

Answer 5

…representative of humans, accessible and available, conducive to experimental manipulation, have well-known genetics and easy to maintain in labs in terms of both cost and space.

e.g mice, fish, worms and flies

Invertebrates are often used (e.g. fruit flies and roundworms) as well as vertebrates.

The organisms used have a lot in common with humans so can be used to study human physiology.

Question 6

Zebrafish are used in this course…

Answer 6

This is a small tropical freshwater fish originally from Asia. It was established as a model organism by George Streisinger back in the 1980s.

Question 7

Zebrafish is used as a number of advantages over other organisms makes them ideal

Answer 7

• They fertilise externally meaning eggs can be collected directly from the medium and have their rapid development in 3 days in controlled conditions
• The embryos are also transparent meaning visualisation of development can simply be done under the microscope
• The genome of zebrafish has also been completely sequenced which allows for a wide range genetic manipulation
• Zebrafish also allow high throughput approaches as one female mating produces hundreds of embryos (differentiating factor compared to mice)
• Zebrafish are also very conducive to embryological and imaging approaches

Question 8

The life cycle of a zebrafish

Answer 8

The embryo hatches after 3 days of development as larva.

After 1 to 2 months, it becomes a juvenile before it matures into an adult after 3 months.

The cycle of development is very fast.

Question 9

24 hours post-fertilisation

Answer 9

…organogenesis is well underway and the embryo corresponds to a 45-50 day old embryo in humans.