What precautions you have to take in the observation of internal structure of mammalian kidney?

Explanation

Aim : Observation of the internal structure of mammalian heart.
Materials required : Freshly collected specimen of heart of sheep/goat from the butcher, soda straws, sharp and long blade/scalpel, tray and jug of water, dissection scissors,and foreceps.
Procedure :
1) Wash the heart thoroughly so that, blood is completely drained from the chambers.
2) Take the soda straws and insert them into the stamps of the blood vessels.
3) Observe the arrangement of blood vessels on the wall of the heart.
4) Keep the heart in the tray in such a way that a large arch like tube facing upwards. This is ventral side.
5) Now take a sharp blade or scalpel and open the heart in such a way that the chambers are exposed.
6) Observe the thickness of the wall of the heart, number of chambers, size of the chambers, difference between the chambers, connection of chambers to each other.
7) You can observe white colored structures in the lower part of the heart, note down the size, shape and to which parts they are attached.