hand writing exocrine gland on blackboard, concept background

hand writing exocrine gland blackboard concept background abdomen alveolar animal biology board cell covered endocrine epithelium gallbladder genitalia glandular histological histology insulin intestinal intestine invasion light mammal chalk medicine microbiology micrograph microscope microscopic microscopy pancreas papilla physiology pink prostate prostatic rat science small submucosa surrounding tissue tubules black