ANSC 313 Lecture Notes - Lecture 9: Histogenesis, Teratology, Organogenesis
Inheritance patterns!
single gene!•
chromosomal!•
multifactorial!•
Teratogenic!•
!
"spectrum" of inheritance patterns!
single gene as main genetic patter!•
multifactorial is at least three or more genes plus the environment!•
teratogenic is much more about environment !•
!
teratogenesis: abnormal development influenced by drugs, viruses, chemicals, radiation, that
occur in utero!
there fore a mammalian phenomenon!•
normally we don't refer to this in birds and things that are going outside of the parent!•
!
teratogens!
genetic background!•
predisposition to the teratogen!◦
predisposition to the malformation!◦
exposure (environmental)!•
time & length ( time in gestation it hits and the length it is there for)!◦
dose!◦
!
generalizations!
animal pregnant or lactating at time of exposure (rarely through male)!•
few effects last from prior to conception!•
generally we are talking about it happening while the annual is already pregnant !◦
most effects have a two week delay!•
because the teratogen has to be metabolized before it goes to the placenta into the fetus!◦
"preimplantation" a "safe" period.....or embryo dies!•
usually think its better that the embryo dies then carrying it and having a malformed calf!◦
primarily congenital defects!•
!
!
Development stage at time of exposure!
blastocyst ( if dose is high enough it dies --> lethality) !•
organogenesis( organs are developing --> structural defects)!•
histogenesis (later have a gut and is being developed further, cells deciding what their function •
will be--> microscopic changes)!
growth ( has formed everything so just causes --> stunting i.e. a runt)!•
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critical periods of development!
!
!
access of teratogenic agent!
direct!•
radiation!◦
microwaves!◦
ultrasound!◦
Document Summary
preimplantation a safe periodor embryo dies usually think its better that the embryo dies then carrying it and having a malformed calf primarily congenital defects. Malnutrition general low birth weight o spring (i. e. runts) if general it is better then being speci c speci c dietary de ciencies twisted legs ( arthryogryposis) manganese de ciency. Viruses by products of the cigarette industry piglets develop sti and swollen joints bovine viral diarrhea (bvd) abortion and central nervous system damage if early it will abort. Diseases diabetes in dogs insulin ( treatment in most animals) is a teratogen for those who do not have diabetes or uctuation in glucose. Twinning in most animals is considered aa high risk pregnancy it is not a natural state sheets and goats twin very often and have no problems with it horses and cows don"t twin very often so have problems. Twin mortality horses ( draft twin more easily then light horses)
