The fine structure of ventricular cells in the brains of mouse embryos homozygous for the loop-tail gene.

The neural tube in normal (+/+), heterozygous (Lp/+), and abnormal (Lp/Lp) mutant mouse embryos ranging in age from 10 to 12 days of gestation was studied by means of transmission electron microscopy. In the abnormal embryos, ventricular cells in defective regions of the brain show distortions and crowding together of internal cellular processes and a decrease in blebs and bulbous projections, as compared with their normal counterparts. At 12 days' gestation the abnormal brains show a scarcity of the T-shaped internal cellular processes characteristic of normal brains. The abnormal brains also show increased amounts of intercellular space and extensive gaps between the cells, particularly in basal regions. There are no striking differences between the normal and abnormal brains at 10 to 12 days' gestation with respect to the appearance and distribution of cilia, microfilaments, microtubules, tight junctions, and ribosomes.