Pregnancy and Fetal Development Flashcards
True or False: Early embryos are distinguishable between species.
False.
When do critical organ systems develop?
Early.
When do embryos start rapidly gaining weight?
The last trimester, when PL increases.
What are the three ways to estimate the age of an embryo?
- Crown-rump length.
- Circumference of the head.
- Length of long bones (femur, tibia, radius).
What are the three factors that influence fetal growth?
- Genetics.
- Fetal Hormones.
- Environment.
What are the contributors to genetic differences?
- Species.
- Genotype.
- Breed.
- Litter size.
*Overall: Animals grow at different rates, and smaller litters grow faster.
What are the contributors to environment differences?
- Too much or too little nutrition.
- First baby is the smallest, and size increases until the third baby.
- Mother’s size determines the amount of room the fetus has to grow.
- Decreased blood flow, smaller fetus.
- Decreased placenta size, smaller fetus.
What three hormones contribute to fetal growth?
- Thyroid.
- Insulin.
- Growth hormone.
What does the thyroid do for fetal growth?
Skeletal and muscular development.
What does insulin do for fetal growth?
Increased energy substrate availability and stimulates placental growth.
What does growth hormone do for fetal growth?
Stimulates fetal growth.
What allows the uterus to change size during pregnancy?
- Hyperplasia (increase in the number of cells).
- Stretching.
- Hypertrophy (increase in the size of cells).
What hormone increases in all animals during pregnancy?
P4.
In mares, what structure disappears in response to endometrial cup formation?
- The primary CL.
What two structures produce P4 in order to maintain the pregnancy?
- The CL.
- The placenta.
*In some species, the placenta does NOT take over P4 production.
