Teeth are the dermal derivatives of integument They are developed as a result of calcification in the mucous membrane of the l cavity. Along with the ridge of the two jaws, the teeth are arranged in a row. The teeth are present in almost all the mammals except in a few mammals In whale, the teeth are fused into plates and lost in the adult stage of Ant eaters. But in Echidna (spiny ant eater) the teeth are absent even in the embryo.
Structure of tooth: Each typical mammalian tooth is placed in the socket over the jaw bone. It is distinguished into three main pads. 
1) Root - It is the basal part embedded in the bony socket.
2) Neck - it is the part above the root enclosed by the gum
3) Crown - It is the upper part beyond the surface of the gum.
The toot is separated from the socket by a vascular pridontal membrane. The vertical section tooth consists of the following parts.
I) Pulp cavity: The entire tooth encloses a central pulp cavity surrounded by a layer of odontoblast cells filled with soft pulp. It is made up of connective tissue, blood vessels and nerve fibers.
II) Dentin: A substance chemically similar to bone- dentine forms the major part of the tooth. But the dentine is permeated by numerous thin canaliculi.
III) Enamel: It is present over the de in the crown and neck regions of the tooth. It is hardest and contains only traces of living matter.
IV) Cement: It surrounds the denting of the root portion of the tooth. It is bony in nature,
The next topic is Mammalian dentition characters
awsm ans
ReplyDeleteAbhijan
ReplyDeletethank you very much,