Teratology I

Question 1

4 Causes of teratology?

Answer 1

1. Genetic
2. Nutritional
3. Infectious
4. Toxins

Question 2

Definition of teratogen

Answer 2

Increases the occurence of structural or functional abnormalities in the offspring after administration to:

Either parent before conception

Female during pregnancy

Directly to the developing fetus

Question 3

What does susceptibility vary with?

Answer 3

Developmental stage at time of exposure

Question 4

What occurs if exposure occurs durring predifferentiation (1-32 cells)

Answer 4

Interferes with implantation

Typically ends in death

Question 5

What occurs if exposure occurs during early differentiation (gastrulation, patterning, morphogenesis)

Answer 5

Impacts on structural development

Greatest impacts of teratogens

Question 6

What occurs if exposure occurs during Advanced organogenesis?

Answer 6

Major structural abnormalities

Question 7

Difference between exposure at early differentitation and advance organogenesis?

Answer 7

Early differentiation - can have complete absence of organ

Advanced organogenesis - At least portion of organ present

Question 8

What is Aneuploidy?

Answer 8

Abnormal number of chromosomes

Question 9

What is polyploidy?

Answer 9

More than two paired (homologous) sets of chromosomes

Question 10

What is most common result of chromosome abnormalities?

Answer 10

Most are aborted

Question 11

Affect of gametogenesis arrests in females

Answer 11

Longer they are arrested the greater the chance of abnormalities

Question 12

What is the most common chromosomal abnormality in the horse?

Answer 12

XO, only a single sex chromosome is present

Question 13

What is dysgenesis?

Answer 13

Abnormal-growth

Question 14

What are chimeras?

Answer 14

Sharing of genetic material because of vascular anastomoses in twins of opposite sex

Question 15

What are freemartins in cows/

Answer 15

Male sex hormones of male twin influence female twin, male can be affected too

Question 16

What is intersex

Answer 16

External characteristics of both male and female, cant tell difference whether male or female

Question 17

What are the most common reasons for abnormal chromosome structure?

Answer 17

Radiation

Chemicals

Question 18

Two possible abnormal chromosome structures

Answer 18

1. Chromosome breakage or deletions
2. Translocations, inversion and centric fusion

Question 19

Abnormality caused by assisted reproductive technologies?

Answer 19

Large offspring syndrome in cattle and sheep

Question 20

What is hydroallantois

Answer 20

One of the membranes of placenta has a lot of H2O

Question 21

What is the gene in sheep which causes for large offspring syndrome

Answer 21

Insulin growth factor 2 (IGF2)

Question 22

WHat is the importance of placenta differences?

Answer 22

Different types of drugs which cant cross placenta in one species may cross in another

Question 23

What is the importance of SER?

Answer 23

Any chemical/drug/toxin that requires metabolic activation to act as teratogen requires presence of SER

Question 24

What does effect of toxicity depend upon?

Answer 24

Route or site of exposure

Amount or dose

Duration

Frequency or rate of exposure

Individuals genetic resistance, developmental stage, health status and age

Question 25

Forms of absorbtion?

Answer 25

Oral Mucous membranes Skin IV/IM

Question 26

Why are teratogens not specific, and what does this result in?

Answer 26

Teratogens are usually not specific because of common pathways Therefore can see different manifestations with same teratogen

Question 27

What are 5 common pathways

Answer 27

Cell division Mitochondria Cell migration Blood vessel Limb development

Question 28

9 Teratogen Mechanisms

Answer 28

Precursors, lack of Mutation Altered DNA Reduced Energy Source Enzyme inhibition Mitotic Interference Osmolar Imbalances Chromosomal Abnormalities Altered Membranes

Question 29

What is syndactyly

Answer 29

Failure of cell death between digits Fusion of digits

Question 30

6 causes of abnormal embryogenesis

Answer 30

Mechanical Disruption Cell Death Failure of Cell interaction Altered Differentiation Schedules Impaired Morphogenetic movement Reduced Biosynthesis

Question 31

4 types of mechanical disruption

Answer 31

Hematoma Tumor Xrays Edema

Question 32

What does ectopic ureters mean

Answer 32

Ureters dont end up where they should, not connecting to bladder

Question 33

Two examples of Impaired morphogenic movement

Answer 33

Ectopic ureters Arthogryposis

Question 34

Two ways that arthogryposis occurs

Answer 34

Extrinsic - Crowding - decreased amniotic fluid Intrinsic - Neurological - Connective tissue abnormalities

Question 35

3 characterizations of Arthogryposis

Answer 35

Joint Contracture - Joint is smaller Muscle weakness Fibrosis