Which of the following glands is part of both the lymphatic and endocrine systems?

The thymus is unique in that it is considered a part of both the lymphatic and endocrine systems. It plays a crucial role in the immune system by producing and maturing T lymphocytes (T cells), which are vital for adaptive immunity, thus linking it to the lymphatic system. At the same time, the thymus releases hormones, such as thymosin, which are involved in the regulation of immune responses, thereby connecting it to the endocrine system.

Understanding the functions of the thymus is key when differentiating it from other options. The liver, while involved in numerous metabolic and regulatory functions, does not primarily function in the lymphatic system, nor does it release endocrine hormones that fit within the typical categorization of glands. The spleen primarily plays a role in filtering blood and immune response but is not classified as an endocrine gland. The pituitary gland, on the other hand, is a significant component of the endocrine system, regulating various hormonal functions in the body, but it does not have a direct role in the lymphatic system.

Thus, the thymus stands out as the gland that operates within both systems, highlighting its dual functions in immunity and hormone production.