Extracellular breakdown of collagen by mice decidual cells. A cytochemical and ultrastructural study

The interaction of antimesometrial decidual cells and collagen fibrils was studied by light microscopy and ultrastructural cytochemistry in fed and acutely fasted mice on days 9-11 of pregnancy. Fibrillar elements in the extracellular space consisted of collagen fibrils and filamentous aggregates (disintegrating collagen fibrils). Intracellular vacuoles exhibited typical collagen immersed in electron-translucent material (clear vacuoles) and faint cross-banded collagen immersed in electron-opaque material (dark vacuoles). Fibrillar elements showed extracellular acid phosphatase activity which was stronger in the region of mature decidua than in predecidual cells region in all animals; it was conspicuous in mature decidua of fasted animals. Intracellular acid phosphatase activity was observed in dark vacuoles and lysosomes, and was absent in clear vacuoles in all cells studied. Since acid phosphatase activity reflects the presence of lysosomal hydrolases in general, the results indicate that breakdown of extracellular collagen occurs by release of lysosomal enzymes by decidual cells and also by internalization of collagen for intracellular degradation in fed and fasted mice. Collagen breakdown may be part of the process of tissue remodeling in mature and predecidual regions, however, in mature decidua, collagen breakdown is enhanced and may therefore contribute to nutrition of the fetus, specially in acutely fasted mice.

Quantitative ultrastructural and ultracytochemical analysis of lysosomes in the trophoblast of human placentas at term

El objetivo del presente trabajo fue analizar la presencia de lisosomas en el sinciciotrofoblasto de placentas humanas a término cultivadas y no cultivadas. Se realizó el estudio ultraestructural y ultracitoquímico para fosfatasa ácida mediante dos técnicas que emplean distintos sustratos y análisis morfométricos en 7 placentas humanas normales a término. Dos de ellas se mantuvieron previamente en cultivos de tejido durante 48 h. El estudio reveló la presencia de escasos cuerpos densos lisosomales con localizaciones supranucleares en relación con vacuolas de endocitosis y principalmente en regiones adelgazadas del sinciciotrofoblasto. La población lisosomal representó un 2,8% a 4,0% de la superficie sincicial. De acuerdo a los resultados, se sugiere que los lisosomas de placentas humanas e términos participarían en el intercambio materno fetal