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Title: Cell proliferation in normal epidermis

A detailed examination of cell proliferation kinetics in normal human epidermis is presented. Using tritiated thymidine with autoradiographic techniques, proliferative and differentiated cell kinetics are defined and interrelated. The proliferative compartment of normal epidermis has a cell cycle duration (Tc) of 311 h derived from 3 components: the germinative labeling index (LI), the duration of DNA synthesis (ts), and the growth fraction (GF). The germinative LI is 2.7% +/- 1.2 and ts is 14 h, the latter obtained from a composite fraction of labeled mitoses curve obtained from 11 normal subjects. The GF obtained from the literature and from human skin xenografts to nude mice is estimated to be 60%. Normal-appearing epidermis from patients with psoriasis appears to have a higher proliferation rate. The mean LI is 4.2% +/- 0.9, approximately 50% greater than in normal epidermis. Absolute cell kinetic values for this tissue, however, cannot yet be calculated for lack of other information on ts and GF. A kinetic model for epidermal cell renewal in normal epidermis is described that interrelates the rate of birth/entry, transit, and/or loss of keratinocytes in the 3 epidermal compartments: proliferative, viable differentiated (stratum malpighii), and stratum corneum. Expected kinetic homeostasis in the epidermismore » is confirmed by the very similar ''turnover'' rates in each of the compartments that are, respectively, 1246, 1417, and 1490 cells/day/mm2 surface area. The mean epidermal turnover time of the entire tissue is 39 days. The Tc of 311 h in normal cells in 8-fold longer than the psoriatic Tc of 36 h and is necessary for understanding the hyperproliferative pathophysiologic process in psoriasis.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
6663247
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Invest. Dermatol.; (United States); Journal Volume: 82:6
Research Org:
Department of Dermatology, University of California, California College of Medicine, Irvine
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; EPIDERMIS; CELL PROLIFERATION; AUTORADIOGRAPHY; THYMIDINE; TRITIUM COMPOUNDS; ANIMAL TISSUES; AZINES; BODY; EPITHELIUM; HETEROCYCLIC COMPOUNDS; LABELLED COMPOUNDS; NUCLEOSIDES; NUCLEOTIDES; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANS; PYRIMIDINES; RIBOSIDES; SKIN; TISSUES 550301* -- Cytology-- Tracer Techniques