Mh. Baumann et al., ELECTRON-MICROSCOPIC ANALYSIS OF THE NORMAL AND THE ACTIVATED PLEURALMACROPHAGE, Experimental lung research, 19(6), 1993, pp. 731-742
Despite an apparent role in pleural pathophysiology, little informatio
n is known about pleural macrophage morphology. Intrapleural tetracycl
ine (TCN) results in pleural macrophage influx and pleural fibrosis; i
ntrapleural carrageenan (CAR) induces macrophage influx without ensuin
g fibrosis. Pleural macrophages collected from normal (NL) and TCN- or
CAR-exposed rabbit pleural spaces were examined with electron microsc
opy. Cellular size; number of microvilli; pseudopods; coated pits (CP)
and coated vesicles (CV); and prevalence of golgi, rough endoplasmic
reticulum (RER), and intermediate filaments (IF) were determined. The
means of each variable in each group were assessed by one-way analysis
of variance, with post boc testing performed by Scheffe F test; p les
s-than-or-equal-to 0.5 was considered significant. TCN-stimulated pleu
ral macrophages were characterized by their small perimeters. CAR-indu
ced pleural macrophages were marked by their large size and abundant i
ntracellular amorphous material. They bad larger perimeters, areas, an
d diameters than the TCN-induced or normal macrophages and thus smalle
r numbers of CV + CP per area. The normal pleural macrophages were cha
racterized by more IF, microvilli, and microvilli per perimeter than e
ither the CAR- or TCN-induced pleural macrophages. No differences betw
een groups were found in nuclear cytoplasmic ratios, number of pseudop
ods, and content of golgi or of RER. The results suggest that normal p
leural macrophages and TCN- and CAR-induced pleural macrophages differ
morphologically and that these morphologic differences reflect functi
onal differences.