Zinc-Deficient Diet Decreases Fetal Long Bone Growth Through Decreased Bone Matrix Formation in Mice

This study evaluated the effects of zinc on skeletal development during fetal development in pregnant ICR mice fed a zinc-deficient (3 mg/kg) or zinc-adequate (30 mg/kg) diet. We also included a group pair-fed with the zinc-deficient group to control for decreased appetite due to zinc deficiency. Developing fetuses at embryonic day 18.5 were removed by cesarean section, and the skeletal development was evaluated by histological analysis as well as by body weight and longitudinal growth measurement. Reduced maternal food intake in the zinc-deficient and pair-fed groups resulted in a marked and significant (P < .05) decrease in fetal weight compared to that of the zinc-adequate group. However, fetal length retardation in the pair-fed group was less marked than in the zinc-deficient group, suggesting that reduced supply of zinc from maternal circulation may play a role in longitudinal growth through skeletal development. The fetal developing tibia of the zinc-deficient group showed marked shortening of diaphysis and a mild narrowing of the hypertrophic chondrocyte zone width with increased osteoclast number, but there was no influence on the mineralization of bone matrix. This may be the result of reduced activation of osteoblasts and maturation of chondrocytes with increased osteoclastic activity, suggesting that zinc deficiency during the fetal development has a greater impact on the matrix formation of bone than the mineralization of bone matrix.