Three-dimensional reconstruction from serial sections
= Three-dimensional reconstruction from serial sections
{title2=$V=\int A(z)\,dz$}
Aligned two-dimensional sections constrain the three-dimensional structure of a specimen. For parallel sections of known spacing $\Delta z$, the <Riemann sum> $\sum_iA_i\Delta z$ approximates volume. Distortion, missing sections and alignment errors constrain the reconstruction; the volume estimate alone does not determine the identity or developmental fate of each visible structure.