Difference Between Thymus and Thyroid

Thymus vs Thyroid

Glands are the organs that secrete substances either into the blood stream or into cavities inside the body. The main glands can be divided into two categories; endocrine and exocrine glands. (Read the Difference between endocrine and exocrine glands). Endocrine glands are the glands that secrete substances called hormone directly into the bloodstream. Both thymus and thyroid produces various hormones, but belong to separate systems because of their functionality in a biological system. Hence, there are many differences exist between these two organs.


Difference Between Thymus 

Thymus is a specialized organ of the adaptive immune system. It is composed of two identical lobes and situated anatomically in the anterior superior mediastinum, in front of the heart. The main components of thymus are the lymphoid thymocytes and the stromal cells. Thymus is responsible for providing an inductive environment for the development of T-lymphocytes. In addition, the stromal cells of thymus can select a functional and self-tolerant T- cell repertoire. Therefore, the induction of central tolerance is considered as a most important function of thymus.

At birth, thymus is about 5 cm in length, 4 cm in breadth, and 6 mm in thickness. Unlike the other organs like kidneys, liver and heart, the thumus reaches its maximum weight (20 to 37 g) by the time of puberty. After puberty, it shrinks with time and becomes scarcely distinguishable from surrounding fatty tissue. When consider the histological features of thymus, it can be divided into a central medulla and a peripheral cortex, which is encapsulated by an outer capsule. 


Difference Between Thyroid 

Thyroid is one of the largest endocrine gland, and only gland that stores its own secretions. It lies in the neck, below the thyroid cartilage. This gland produces two principle thyroid hormones; triiodothyronine and thyroxine. These hormones regulate the rate of metabolism, protein synthesis and affect the growth and function of many other systems in the body. In addition, thyroid also produces the calcitonin hormone, which serves in calcium homeostasis in the body. All these functions and hormonal activities of thyroid are controlled by the thyroid stimulating hormone (TSH) produced by the anterior pituitary. Histologically, thyroid gland consists of thyroid follicles, which are made up of follicular cells, and parafollicular cells.

What is the difference between Thymus and Thyroid?

• Thymus is an organ or gland of the lymphatic system, whereas thyroid is a gland of the endocrine system.

• Thymus is located anatomically in the anterior superior mediastinum, in front of the heart. In contrast, thyroid is located in the neck, below the thyroid cartilage.

• Thymus produces matured T- lymphocytes, and hormones including thymosin, thymic humoral factor (THF), thymic factor (TF) and thymopoietin. In contrast, thyroid produces thyroid hormones including triiodothyronine, thyroxine, and calcitonin.

• Thyroid regulates the rate of metabolism, proteins synthesis and the responsiveness of the body to other hormones, whereas thymus provides an inductive environment for the maturation of T- lymphocytes.


Read more:

1. Difference Between Thyroid and Parathyroid

2. Difference Between Solid Thyroid Gland Nodule and Simple Fluid-Filled Sac

3. Difference Between Lymphocytes and Leucocytes