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Morphometry and computerized three-dimensional reconstruction were used to study the relationship between apical constriction of neuroepithelial cells and the pattern of bending of the neuroepithelium in the developing neural tube of the 12-somite mouse embryo. The neuroepithelium of the mouse exhibits prominent regional variations in size and shape along the embryo axis. The complex shape of most of the cephalic neural tube (e.g., forebrain and midbrain) is due to the coexistence of concave and convex bending sites whereas more caudal regions (e.g., hindbrain and spinal cord) generally lack sites of convex bending and have a relatively simple shape. The apical morphology of neuroepithelial cells was found to be correlated more closely with the local status of bending of the neuroepithelium than with the specific region of the neural tube in which they are located. In areas of enhanced apical constriction, microfilament bundles were particularly prominent. Morphometry revealed that patterns of bending of the neuroepithelium were correlated almost exactly with those of apical constriction throughout the forming neural tube. These findings support the idea that apical constriction of neuroepithelial cells, resulting from tension generated by microfilament bundles, plays a major role in bending of the neuroepithelium during neural tube formation in the mouse.

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. (1968). Eflects of Maternal Essential Fatty-acid Deficiency o n Neonatal Rat Brain. DEVELOPMENTAL PSYCHOBIOLOGY, l(4) 225-229. Female weanling rats were raised to sexual maturity on either a normal stock diet or an essential fatty-acid (EFA) deficient diet, and then bred. Brain weight and lipid composition of the offspring from these animals were measured as part of an investigation into factors contributing to the early death of EFA-deficient progen). Lactation failure does not seem to be an adequate explanation of the early deaths since the dead EFA-dehcient offspring frequently have milk in their stomachs. Maternal behavior including nesting was lacking, however, in EFA-deficient dams. The EF4-deficient brains weighed less than normal neonatal brains, and frequently had subdural hemorrhaging. Relative to body weight, however, some "sparing" of the brain was apparent. Total hi aiii sterol concentration was not measurably different, but fatty-acid composition of total brain lipid and phospholipid was. T h e EFA-deficient offspring had relatively less arachidonate and other EFA-related fatty acids, while the proportion of ti ienoic acids, principallr 20:3 and 2 2 3 was increased considerably. In phosphatidyl ethanolarnine, the proportion of 16:O was particularly elevated in the EFA-deficient brains. T h e results are discussed in relation to the integrity of inyelin and the synthesis of prostaglandins, as possible factors in the premature death of EFA-deficient progeny.essential fatty acid deficiency brain myelin maternal behavior lipid and phospholipid multiple sclerosis prostaglandins HE PARTICULARLY high rate of fetal and early post-

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