LBB: abnormal signalling

Question 1

define a teratogen

Answer 1

A factor/agent that can disturb the development of an embryo

Question 2

Define teratogenesis

Answer 2

the process by which congenital malformations are produced by a fetus

Question 3

Describe the effect of teratogens in pre-embryonic stage of development?

Answer 3

If 1 or 2 cells are killed: the embryo can compensate by regulative development
If more cells are killed - embryo will be lost (spontaneously aborted)

Question 4

Describe the effect of teratogens in embryonic stage development?

Answer 4

teratogens are highly effective

At this stage, the organ systems are developing and each organ has its own period of maximal sensitivity to teratogens

Question 5

Describe the effect of teratogens in fetal stage of development?

Answer 5

Susceptibility to tetragons is reduced and only functional deficits and minor abnormalities occur in response to teratogens.

Question 6

List some teratogens

Answer 6

Mechanical factors
Industrial pollutants 
Hormones
Drugs and chemicals 
Infectious agents (parasites, viruses)

Question 7

Give examples of environmental teratogens

Answer 7

Drugs and chemicals e.g. thalidomide
Industrial pollutants
Hormones e.g. androgems. synthetic oestrogens (in utero increase risk of carcinoma)