Which structure secretes hormones directly into the bloodstream without using a duct?

lacrimal gland

adrenal gland

oil gland

salivary gland

The answer is adrenal gland.

Hormones are chemical signaling molecules secreted by glands, either endocrine or exocrine. Endocrine glands secrete hormones directly into the bloodstream without using a duct, unlike the exocrine glands. Endocrine glands include pancreas, hypothalamus, pineal gland, pituitary gland, thyroid gland, parathyroid gland, adrenal gland, ovaries, testes