Am. J. Respir. Cell Mol. Biol., Vol 10, No. 4, Apr 1994, 462-469.
Heterogeneity of sulfated microdomains within basement membranes of pulmonary airway epithelium
J Khosla, MT Correa and PL Sannes
Department of Anatomy, Physiological Sciences, and Radiology, North Carolina State University, College of Veterinary Medicine, Raleigh 27606.
The purpose of this study was to determine whether the cytochemically
defined distribution of sulfated macromolecules is significantly different
in microdomains of basement membranes (BMs) associated with different
levels of pulmonary airways. The high iron diamine-
thiocarbohydrazide-silver proteinate (HID-TCH-SP) technique, which is
highly specific for sulfate esters of glycosaminoglycans and some
glycoproteins, was used as a probe to compare the BM of trachea, bronchi,
and three different sizes of bronchioles. When HID-reactive sites were
counted and statistically compared, significant differences were found
between the three known anatomically distinct layers of the BM--lamina
lucida (LL), lamina densa (LD), and lamina reticularis (LR)-- relative to
the airway level. The highest concentration of HID reactivity in trachea,
bronchi, and large bronchiole was found in LR and the lowest in LD. By
comparison, HID-reactive sites were found to be more concentrated in the LL
in medium and small bronchioles. HID reactivity was consistently low in LD
as compared with LL and LR in all five locations. The overall degree of HID
reactivity in BMs was clearly highest in large bronchioles and lowest in
medium and small bronchioles. This cytochemically detectable heterogeneity
in the distribution of HID reactivity in BM microdomains may represent
specific compositional differences in pulmonary BMs which are important
determinants of epithelial cell function and might be expected to impact
key biologic processes in normal and pathologic states.
