Which of the following endocrine glands is not found in pair in humans?

In the human endocrine system, glands are categorized as either paired or unpaired based on their anatomical occurrence. The pituitary gland, also known as the hypophysis, is a single, unpaired master gland located at the base of the brain below the hypothalamus [2]. It consists of distinct lobes but remains a singular structure. In contrast, other endocrine glands mentioned in the options occur in pairs. Humans possess two adrenal (suprarenal) glands, one located atop each kidney. Similarly, the gonads are paired structures: males have two testes, and females have two ovaries [1]. While the pituitary and pineal glands are notable unpaired structures in the brain, the adrenal glands and gonads are bilateral. Therefore, the pituitary gland is the correct answer as it does not occur in a pair [2].

Sources

1. [2] https://egyankosh.ac.in/bitstream/123456789/58298/1/Unit%209%20Endocrine%20System.pdf
2. [1] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/pituitary-gland