Which of the purely endocrine organs contain modified neurons that produce and secrete neurohormones?
a. the gonads
b. the pineal gland and the thymus
c. posterior lobe of the pituitary and adrenal medullae
d. only the adrenal medullae

D. Only the adrenal medullae

Explanation:

The adrenal medulla is the inner region of the adrenal gland. It consists of the modified sympathetic ganglion of the autonomic nervous system and develops from the same embryonic tissue as all other sympathetic ganglia. The cells of the adrenal medulla lack axons and are [present in the form of clusters around large blood vessels.

The chromaffin cells of adrenal medulla serve the endocrine function. These cells are innervated by sympathetic preganglionic neurons of the ANS. The adrenal medulla secretes epinephrine and norepinephrine which are called neurohormone as being secreted by neurons.

c. establishing proper sleep hygiene