Acute food restriction increases collagen breakdown and phagocytosis by mature decidual cells of mice

An ultrastructural study was undertaken on antimesometrial mature decidual tissue of fed and food-restricted mice, on day 9 of pregnancy. The mean ad libitum food intake was established on mice from the 8th till the 9th day o f pregnancy. Fed mice were used as controls. Experimental animals were divi ded into two groups: one was allowed to feed 25% of normal diet and the oth er 50%. Extracellular collagen fibrils were scarce in fed animals and consp icuous in food restriction. Granular electron-dense deposits and filamentou s aggregates of disintegrating collagen fibrils were observed in all food-d eprived mice but were rarely noted in fed animals. Intracellular vacuolar s tructures exhibited other typical cross-banded collagen immersed in finely granular electron-translucent material (clear vacuole) or electron-dense ma terial containing collagen fibrils with a faint periodicity (dark vacuole), The clear and dark vacuoles were scarce in fed animals and evident in food -restricted mice, mainly in those 25% food restricted. Although collagen br eakdown may be part of the normal process of decidual tissue remodelling ou r results suggest that it is enhanced in food-restricted animals. Thus it s eems that collagen breakdown is a normal mechanism that may be regulated by the food intake of the pregnant animal. (C) 2001 Harcourt Publishers Ltd.