RT Book, Section
A1 Chandrasoma, Parakrama
A1 Taylor, Clive R.
SR Print(0)
ID 185466
T1 Chapter 16. Disorders of Cellular Growth, Differentiation, & Maturation
T2 Concise Pathology, 3e
YR 1998
FD 1998
PB The McGraw-Hill Companies
PP New York, NY
SN 9780838514993
LK accessphysiotherapy.mhmedical.com/content.aspx?aid=185466
RD 2024/04/24
AB The  cells  of  the  body  continue  to  grow,  divide,  and  differentiate  throughout  life.  Normally,  growth  and  differentiation  are  controlled  in  such  a  way  as  to  maintain  the  normal  structure  of  a  particular  tissue.  In  tissues  characterized  by  continuous  cell  loss  (skin,  intestinal  mucosa,  blood),  labile  stem  cells  continuously  undergo  mitosis  to  replace  lost  cells.  Stem  cells  frequently  differentiate  from  a  primitive  to  a  mature  form  during  this  process—eg,  normoblasts  in  bone  marrow  become  the  erythrocytes  of  the  peripheral  blood.  In  the  skin,  as  superficial  keratinized  cells  are  shed  from  the  surface,  basal  cells  proliferate  at  a  suitable  rate  to  replace  them.  The  newly  produced  basal  cells  move  upward,  differentiating  into  squamous  cells  that  undergo  nuclear  and  cytoplasmic  changes  to  become  the  superficial  cornified  layer  of  cells.  When  the  epidermal  turnover  rate  is  normal,  the  skin  appears  normal  on  histologic  examination;  but  if  the  rate  is  greatly  increased,  as  occurs  in  psoriasis,  cells  do  not  fully  mature,  and  abnormalities  are  seen  both  on  gross  examination  and  at  the  histologic  level.