The lymph nodes in the knee are called the:

A. Lacteal is a lymphatic vessel located in the villi of the small intestine that absorbs fats, not the enlarged portion of the thoracic duct.
B. Hilum refers to the area on an organ where vessels, nerves, or ducts enter or leave, but it is not the enlarged portion of the thoracic duct.
C. The Right lymphatic duct is a separate duct that drains lymph from the right side of the body, not the enlarged portion of the thoracic duct.
D. Cisterna chyli is the enlarged, sac-like structure at the lower end of the thoracic duct, where lymph from the lower body and digestive organs (containing chyle) is collected before being transported into the thoracic duct.

A. The spleen does not shrink after puberty. It remains an active part of the immune and blood filtration systems throughout life.
B. The thymus (note: it appears misspelled as "Thygus" in the question) is the correct answer. It plays a crucial role in the development of T lymphocytes (T cells) during childhood but begins to shrink and become replaced by fatty tissue after puberty—a process known as involution.
C. The liver does not shrink after puberty. In fact, it continues to grow and function in metabolism, detoxification, and digestion throughout a person’s life.
D. The cisterna chyli is a dilated sac at the lower end of the thoracic duct involved in lymphatic drainage. It does not shrink after puberty and remains functional throughout life.