The cell membrane was one of the cell structures that could be clearly detected using a compound microscope at 400x magnification.
The cell membrane is a thin, flexible barrier that surrounds the cell and keeps the cytoplasm distinct from the outside world. It is apparent as a dark line around the cell's perimeter.
The organelles are housed in the cytoplasm, which is a jelly-like fluid that fills the cell. It appears as a transparent region within the cell membrane.
The nucleus is the cell's regulatory center and houses the genetic material (DNA). It is seen in the center of the cell as a black, spherical structure.
Mitochondria are the cell's powerhouses, producing energy in the form of ATP. They are evident in the cytoplasm as minute, rod-shaped entities.