The pineal body is a small endocrine gland located in the brain.

I have experienced astral projection.

He said he had experienced an out-of-body experience.

Chloroplasts are the locations where photosynthesis occurs in plant cells.

In our medical class, we learned about the function of the pyramidal tract.

It is important to learn about the prevention and treatment of the human immunodeficiency virus.

The human immunodeficiency virus destroys the immune system, making the body unable to fight disease.

A tesseract is a four-dimensional geometric shape.

A 5-cell is a simple convex polytope in four dimensions.

This area is seriously contaminated with radioactive isotopes.