He is majoring in economics.

He is an expert in bacteriology.

He is an expert in pathology.

I study Japanese every day.

He is an expert in virology.

He has a deep interest in teratology.

He is an expert in embryology, studying the developmental processes of many kinds of organisms.

I am majoring in embryology at university.

The president makes the final decisions regarding the operation of the university.

He is a world-renowned scholar.