Functional integrity of regenerative tissue

The cell of the body have been devided into three groups based on their regenerative capacity and also based on evolutional point .

(a)    Labile cells – Labile cells continue to proliferate throughout life . replacing cells which are continuoually being destroyed . They are least specialized cells of the body and have high protential for mitosis . Epithelial surface throughout the body are made up of labile cells . These includes-

i)                    Stratified squamous surface of skin , oral cavity , vagina and cervix .

ii)                  The lining mucosa of all the excretory ducts of the glands of the body like salivary glands , pancreas and billiary tract .

iii)                Columnar epithelium of gastro Intestinal Tract , uterus and tubes .

iv)                Transitional epithelium of urinary tract .

v)                  Connective tissue cells oif haemopoiesis like splenic cells , lymphoid cells of the bone marrow fall in liable cell group .

These cells are constantly replaced after a definite period by the reserved cells . cytotoxic drugs after the liable cells along with the neoplastic cells .

(b)   stable cells -  Stable cells retain thecapacity of proliferation although they do not normally replicate. It is postulated that injury to the stable cells depress the generic programme ( according to the operon model of Gene function ) which induce the mitotic process in the quiescent cell . These cell are more specilaised than the labile cells in evolution ladder . examples cells are –

i)                    Parenchymal cells of the glands throughout the body including liver , pancreas , salivary and endocrinal gland , kidney tubules and glands of the skin .

ii)                  Connective tissue cells such as fibroblast or their m ore primitive progenitors . They are multiprotential cells capable of proliferation throughout life .  The multiproteential fibroblast is further capable of differentiation into other type of connective tissue cells . By metaplastic transformation it may be converted into osteoblast or chondroblast . t amy acquire lipid inside the cell and may be converted into adepocyte .

iii)                Permanent cells -  These are the most specialized calls of the body . Due to absence of ccentrosome in their cells , they have lost the power of mitotic division . They can’t regenerate at all . After necrosis , they are always replaced by connective tissue cells .