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 .
