Why is the anterior pituitary considered to be a true endocrine gland, whereas the posterior pituitary is not?

Answer 1

The anterior pituitary has neuroendocrine cells which secrete their hormones directly into the blood supply. Posterior pituitary is actually a series of nerves that start in the hypothalamus and terminate in the posterior pituitary. The posterior pituitary stores the hormones ADH and oxytocin before releasing them.