developmental toxicology

Question 1

dose-effect relationship of teratogens

Answer 1

• low dose = no effect
• intermediate dose = characteristic malformation
• high dose = lethal

dose depends on: route of administration, bioavailability, maternal metabolism, efficiency of transplacental transfer, etc

Question 2

effect of teratogens during different developmental stages

Answer 2

• 0-2 weeks (all or none period) = lethal or no effect
• 2-8 weeks (embryogenesis) = effect on organ system development
• 9+ weeks = effect on growth of embryo/organs

** exposure must happen at or before development of an organ to affect that system

Question 3

effect of maternal genotype on teratogencitiy

Answer 3

• maternal metabolism of teratogens varies
• maternal PKU => malformations
• maternal diabetes => malformations

Question 4

example of effect of fetal genotype on teratogenecity

Answer 4

• has more influence on teratogen susceptibility than the maternal genotype
• response to phenytoin: embryo homozygous for decrease epoxide hydrolase activity has higher risk of fetal hydantoin syndrome

Question 5

teratogenic infectious agents

Answer 5

Toxoplasmosis
Syphillis
Rubella
Cytomegalovirus
Herpes simplex