Final answer:
A vertical section through the body dividing it into left and right sides is called a sagittal plane, with the midsagittal plane specifically creating equal halves and the parasagittal creating unequal ones.
Step-by-step explanation:
A vertical section through the body that divides it into left and right parts is called a sagittal plane. If the division is exactly in the center, creating two equal right and left halves, it is referred to as a midsagittal or median plane. In contrast, if the plane creates unequal left and right sides, it's termed a parasagittal plane. Conversely, a frontal plane, which can also be called a coronal plane, divides the body into anterior (front) and posterior (back) portions, and a transverse plane, or horizontal plane, divides the body into upper and lower sections.