What is the male reproductive structure called?

The male external organs are seen to be the penis and the two scrotal sacs while the rest are located inside the body.

The sacs contains the testes which produces the male sex hormone called testosterone.

Each testis consists of hundreds of compartments, each packed with many tiny coiled tubes, the seminiferous tubules. The cells lining the tubules gives rise to sperm. The seminiferous tubules join to form larger tubules which eventually form the epididymis. The seminal vesicles, prostate glands and cowpers glands are associated with sperm duct and urethra. The sperm plus these secretions form a milky fluid called the semen.