Question: where do the secretory cells of endocrine glands secrete their products
[{'answer': 'epithelial surface', 'provenance': [{'wikipedia_id': '72672', 'title': 'Exocrine gland', 'start_paragraph_id': 1, 'start_character': 71, 'end_paragraph_id': 1, 'end_character': 89, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'bloodstream', 'provenance': [{'wikipedia_id': '72672', 'title': 'Exocrine gland', 'start_paragraph_id': 1, 'start_character': 362, 'end_paragraph_id': 1, 'end_character': 373, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'directly into the bloodstream', 'provenance': [{'wikipedia_id': '72672', 'title': 'Exocrine gland', 'start_paragraph_id': 1, 'start_character': 344, 'end_paragraph_id': 1, 'end_character': 373, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '72672', 'title': 'Exocrine gland', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 659, 'bleu_score': 0.979896933041101, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 983881216481196725}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '72672', 'title': 'Exocrine gland', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 983881216481196725}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '661769', 'title': 'Parietal cell', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['Parietal cells (also known as oxyntic or delomorphous cells) are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and in the cardia of the stomach. They contain an extensive secretory network (called canaliculi) from which the HCl is secreted by active transport into the stomach. The enzyme hydrogen potassium ATPase (H/K ATPase) is unique to the parietal cells and transports the H against a concentration gradient of about 3 million to 1, which is the steepest ion gradient formed in the human body. Parietal cells are primarily regulated via histamine, acetylcholine and gastrin signaling from both central and local modulators ("see \'Regulation\')".', 'Parietal cells (also known as oxyntic or delomorphous cells) are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor.']}}]}]