Question

Describe 3 different animal species that have been studied to understand pregnancy. Explain three important considerations for choosing an animal model system. Why are animal models useful and yet also limited?

Answer 1

1.MICE:

Mice and rats are the most used species in research .Mice have an important advantage in many genetic manipulated models along with inbreed strains. The mouse has a short gestation period of around 20 days, and it carries a litter size of 5-6, which allows for quick data collection. The placenta is of the hemotrichorial labyrinth type. The newborn mice are neurodevelopmental immature with closed eyes. Because of the larger litter size,it is difficult to measure and follow individual fetal and placental progress. In addition, the small size makes surgical procedures difficult.

2.GUINEA PIGS:

The guinea pigs has as gestation length of around 67 days and gives birth to 3-4 precocious offspring with a well developed nervous system at birth . These characteristics make newborn guinea pigs suitable for research in fetal development. The placenta barrier is hemomonochorial, and it is histologically comparable with the human placenta barrier.In fact the guinea pig is a well establish model to study placentation, and suggested to become one of the most imprtant animal model for new placental studies in pregnancy research. They are affordable and easy to maintain in research environment.Intravenous approaches can be more complicated than for mice and rats due to lack of a long tail.

3. RABBITS:

The rabbit is known for its rapid reproduction with a short gestation of only 30 days and a litter size of around five cubs.Because coitus induces the ovulation, it is possible to time the gestation and obtain a precise age of fetus, which is of practical experiment advantage.In particular , the rabbit has been used to study reproduction and early embryogenesis.The rabbit has a hemodichorial placenta barrier of the labyrinth type . the thickness of trophoblast cell alternates,resulting in thick and areas of the barrier.

CONSIDERATION-

1.Research in the pregnant human is problematic and may pose significant ethical restrictions as the well being of the mother and her unborn baby is critically important .

2.Animal models remain essential to understand the fundamental mechanisms underlying the onset of pregnancy disease ,and to discover improved methods for preventing , diagnosis and treatment.

3. In addition the timing of the study during the gestation needs to be considered, as pregnancy is a dynamic process, which is less in animals.

Animal models remain essential to understand the fundamental mechanisms occurring in fetal medicine and pregnancy disease, such as intrauterine growth restriction, preeclampsia and gestational diabetes.While none of these exactly mirrors the human condition, different pregnant animal models described above have advantage and limitation both.Management of feeding , handling , care is hard for animals.