A longitudinal section — the cross-section obtained by slicing an object or structure along its lengthwise (longitudinal) axis.
設計図の縦断面図を確認して、配管の高さを調整した。
I checked the longitudinal section on the blueprint and adjusted the pipe elevation.
骨の縦断面を顕微鏡で観察すると構造がよくわかる。
Observing the bone's longitudinal section under a microscope reveals its structure clearly.