From which embryonic tissue does the anterior pituitary gland arise?

1. The endocrine system draws on all three embryonic germ layers. 2. The pituitary gland alone arises from two distinct areas of ectoderm. 3. The anterior lobe comes from the oral ectoderm, matching its origin in the primitive digestive tract. 4. The posterior lobe comes from the neural ectoderm at the base of the hypothalamus, matching its neural tissue. 5. Mesoderm gives rise to the steroid-producing glands, the gonads and the adrenal cortex. 6. Endoderm gives rise to the thyroid, parathyroid, pancreas and thymus, so neither layer accounts for the anterior lobe. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 17 "The Endocrine System", section 17.11 Development and Aging of the Endocrine System_