The purpose of this lab is observe the different stages of embryonic development for mama alas, and rats play as a good specimen because they are not too small that it is hard to observe t he stages and they are not too big that it would be difficult to navigate around the specimen’ s internal organs. In addition, rats typically hold a clutch size Of around 12 so if any mistakes air SE during dissection of the sac, there are more opportunities to get a sample embryo the at isn’t too damaged.In order to achieve this goal, students will first observe the different organs o f the specimen in order to understand the functions of each organs.

For example, a after observing the out cavity, a student can predict what type of diet rats have by recording o observations about the specimen’s teeth and palates. After students observe each organ, and thee r contribution to each organ system and contribution to the survival of the rat, students will the en answer and explain the reasons for the structures of the organs.For example, when obese vying the lungs, students will find that the inside of the lungs are elastic and spongy, students will have to explain why the lungs are constructed in that way. Once students have recorded and explained their findings on the organs of the mother specimen, students will move on to observing the embryonic development of the rat embryos/ fetus. Each group will have a specimen with an embryo at different stages o development.Each group will be responsible of locating the ovaries, and cutting Eng open the embryonic sac in order to obtain an embryo sample. Students will then obese eve the different stages of the embryonic development, noting the difference between each sat GE and understanding what may be occurring during these different stages. Data: Stages Development of organs Distinguishable head and tail locationNo placenta found yet A placenta has developed Umbilical cord connect to embryo Embryo developing limbs Skin becomes thicker Internal organs developing Further development of internal organs due to increase in size More distinct limbs and tail Nose and ears developing VI Immense increase in Skin becomes really wrinkled External features Head development Toes under development have become really Further development of limbs Eyes become more developed Detailed, Fetus has Mouth and Eyes developing Excess of skin developed grown into its excess Further spinal cord developmentExternal features more distinct Of skin Questions: 1 .

Based on the teeth and mouth structures, what type of organisms do you the ink that the rat feeds upon? The rat has a longer lower jaw teeth than upper jaw teeth, and most likely fee des on small nuts, fruits and smaller organisms such as smaller rodents. 2. Why would the rat be considered as a collocate in its classification? A rat would would be considered as a collocate because the rat’s blood is our NSA through blood vessels and the rat’s organs are individually covered by their own distinct lay r of epithelium. 3.Why does the rat contain a multiplied liver? The liver is used in order to help detoxify and regulate the substances within t he blood as well as use bile in order to break down lipids for energy. A multiplied liver would be necessary since a rat’s diet consist of various items that may be toxic, and as an active or gamins, the rat would require a consistently high metabolism to support it’s lifestyle which re quires a lot of energy. 4. How would describe the endoderm of the small intestine and why is it adapt Ted in such a way? The endoderm is quite bumpy, which indicates intestinal villous.

The small intent Stint is adapted that way in order to increase surface area and help with absorption Of nutrient TTS, the faster absorption would help support a high metabolism lifestyle with continuously rapid amount of nutrients diffusing into the blood. 5. Why do you think the pregnant rats have more of these fat tissues than MO SST rat specimens? Pregnant rats would have more fat tissues than most rat specimens because t hey require a larger fat reserve in order to provide energy that could both support the mot her and the multiple embryos.