Get the answer of: How to prepare skeleton of animals.
All the bones together of a vertebrate constitute the endoskeleton. The bones are articulated in such a fashion that in addition to support the body weight and allowing free movements of body parts, it forms the framework and gives shape and rigidity to the body and also protect the internal organs.
All the processed bones of an animal joined together in their proper position is termed an articulated skeleton while bones are kept separately in a disarticulated skeleton. The bones of an animal are grouped in two categories.
Axial skeleton consists of skull, vertebral column and ribs, and appendicular skeleton includes limb bones and girdles. In the preparation of a skeleton, under no circumstances the bones of the distal portion of the limbs, viz., wrist to fingers in the forelimb, and ankle to fingers in the hind limb should be separated from one another.
Preparation:
One should strictly follow the following steps in the preparation of a skeleton:
Skinning:
Remove the skin completely. The skin can be easily separated from the body except certain localised areas, e.g., the roof of the cranium of toad.
Removal of viscera and other soft organs:
This includes all the soft structures except the muscles. They are not directly associated with the bones and their removal is easy.
Removal of muscles:
Cut the muscles close to their attachment and insertions into the bones and cartilages and separate them. Care should be taken not to damage the cartilages and the joints. Extra precaution is needed in removing the muscles of the buccal floor and laryngeal region, as the hyoid apparatus located there is liable to easy damage. All the muscles, however, cannot be removed.
The bony frame with the remains of muscles is boiled in water in a submerged state in a covered container. The period required for softening of muscles varies with animal. For a frog or toad, it is about 5 minutes or a little more while for a rodent, rat or guinea pig, it is about 10 to 15 minutes. Prolonged boiling may damage cartilage and articular ends of bones.
Disarticulation and cleaning:
After cooling, transfer the whole thing to a large tray containing water. Carefully separate the limb bones from the girdles and the girdles from the axial skeleton. Remove the muscles, tendons and ligaments with a pair of forceps.
A used tooth brush with straight bristles (not deformed in use) is an excellent tool in the removal of traces of muscles. The water of the tray should be changed frequently and the cleaned materials kept submerged under clear water in a tray during the procedure.
Bleaching and curing:
Fat and other materials still present in the bones encourage microbial growth. These must be removed to preserve the bones. Treat the bones either with chlorine solution or hydrogen peroxide or lime water. The bones are kept immersed in the fluid for a few hours, thoroughly washed with water and dried in a drier or preferably in sunlight.
Polishing and preservation:
In bleaching, the bones turn almost white in colour. Passing the bones through a weak, almost colourless varnish, renders the surface smooth and polished. At the same time it helps in preventing microbial growth. The disarticulated bones if not meant for immediate use, either for preparation of an articulated skeleton or study, should be kept in a properly sealed, air tight polythene bag.