Which of the following is not an endocrine gland?

Complete the following analogy-based questions:
$1$. Hyperglycemia : Diabetes Mellitus :: Beta cells : ....
$2$. Excess Growth Hormone : Gigantism :: Low secretion : .......
$3$. Pineal gland : Melatonin :: Somatostatin : .....

Endocrine glands are

Which of the following is called the "biological middleman"?

Identify the location of secretion and the primary function for the following hormones:
$(1)$ Relaxin
$(2)$ Thyrocalcitonin

Endocrine glands are those glands that pour their secretions into .....