PATH 205.3 Lecture Notes - Fall 2018 Lecture 5 - Gonadal dysgenesis, Microcephaly, Amniocentesis
Document Summary
Objective: to understand the concept of critical stages of organogenesis. Normal prenatal development: early cleavage embryos: loss of cells have no adverse effect. 8-cell stage = morula can remove 1-2 cells w/o affecting the baby: blastocyst stage = occurs after 4 days; any cell loss after this stage - defects. Critical stages of organogenesis: rapid cell division, migration. Most malformations occur by 8 weeks of gestation: brain: susceptible for up to several months after birth. Objective: be able to classify and list a few teratogens. Causes of congenital defects in humans: teratogens, physical: x-ray other radiation sources, chemical, thalidomide (phocomelia, alcohol: iugr (intrauterine growth restriction), dev of brain, facial dysmorphology, microbial: torch, chromosomal abnormalities (2%): sex, somatic, genetic factors (20%, unknown causes (75%) Objective: be able to list common microbial teratogen and their effect on organogenesis (torch) H: herpes virus: transplacental, period of organogenesis, some in first trimester other, especially brain can be affected up to last trimester.
