Disproportionate Growth in Offspring of Manganese-Deficient Rats

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Abstract
Growth of the skull was studied in offspring of normal and manganese-deficient rats from birth to 32 days of age by measuring skulllength, width, and height in alizarin-stained preparations. The deficient animals showed some depression of lengthwise growth of the skull throughout this period. Skull width and skull height were also slightly decreased in the deficient animals on an absolute basis. In relation to their length, however, the skulls of deficient young were wider and higher than those of controls. This difference was very marked at birth. Midline measurements of the skulls of newborn young indicated that the doming of the frontal portion of the skull in deficient offspring resulted from an inhibition of growth in the basal portion of the skull concomitant with dissimilar rates of growth in the cranial bones. Skull dimensions of manganese-deficient adult rats, measured from roentgenograms, also showed an increased ratio of skull height to skull length, although the ratio of width to length was not significantly increased. Brain weights were smaller in the deficient animals on an absolute basis, but in relation to body weight the brains of deficient young were larger than those of controls. Moisture determinations of the brain tissue showed that the increase was not caused by edema. Cerebrospinal fluid pressure was measured in normal and deficient young from three weeks to 6 months of age. No significant differences between the two groups were seen in this respect.