With the event of microwave-antigen retrieval it has become possible t
o detect proliferating cells (staining positive for MiB-1) in cervical
smears containing epithelial fragments and in paraffin sections conta
ining cancerous cervical epithelium. The PAPNET system, using neural n
etwork computing, is able to collect from the slides epithelial fragme
nts with positive-staining nuclei. The nuclei in epithelial fragments
are semiautomatically quantitated using the PAPNET-digitized images. T
he parameter PPN (proportion-positive nuclei), in which the nuclear ar
ea of the positive nuclei is taken into account prove to be superior t
o the proliferation index for distinguishing moderate dysplasia from c
arcinoma in situ. In repair cells, all four quantitative parameters ar
e close to those of moderate dysplasias, indicating that this method i
s unfit for distinguishing these two entities. However, we show that M
iB-1 staining is valuable for the analysis of ''false-negative'' and '
'false-positive'' smears, and for quantifying proliferation in section
s of carcinoma in situ. (C) 1995 Wiley-Liss, Inc.