Complex sentence: Busse was born in Belgard, Pomerania, Prussia (today Białogard, Poland) and studied medicine at the University of Greifswald, and subsequently became an assistant to Paul Grawitz (1850--1932), (his future father-in-law) at Greifswald.
Split into simpler sentences: Busse was born in Belgard, Pomerania, Prussia (today Białogard, Poland). He studied medicine at the University of Greifswald, and subsequently became an assistant to Paul Grawitz (1850--1932), (his future father-in-law) at Greifswald.