1. Bonus Photos

2. 350824 Credit: © Walley Eberhart/Visuals Unlimited Good loam soil rich in humus.

3. Credit: © Carolina Biological/Visuals Unlimited 316419 Pituitary gland section showing growth hormone acidophils LM X30.

4. Credit: © Carolina Biological/Visuals Unlimited 315581 Illustration of hormones, human brain, and hypothalamus. The hypothalamus links the nervous system to the endocrine system via the pituitary gland.

5. Credit: © Carolina Biological/Visuals Unlimited 98647 Thyroid gland cross-section. X55. The main function of the thyroid is to produce the hormones thyroxine, trilodothronine and calcitonin. 25% of all the human body’s iodide ions are in the thyroid.

6. Credit: © Carolina Biological/Visuals Unlimited 316416 Human parathyroid gland. LM X360. The parathyroid gland mainly regulates the calcium level in our bodies for the proper functioning of the nervous and muscular systems.

7. Credit: © Dr. Gladden Willis/Visuals Unlimited 308135 Human thymus gland showing the darker cortex and the pale medulla of each lobule. H&E stain. LM X16. The thymus is important in the development of the immune system in humans and is mostly active before puberty.

8. Credit: © Dr. Gladden Willis/Visuals Unlimited 213288 Normal adult adrenal gland with zona glomerulosa, zona fasciculata, and zona reticularis of cortex. LM X26. Adrenal glands regulate the stress response by synthesizing corticosteroids and catecholamines (including adrenaline and cortisol).

9. Credit: © Dr. Ken Greer/Visuals Unlimited 304788 Thyroid goiter, usually caused by iodine deficiency.

10. Credit: © F.C. Skarva, MD/Visuals Unlimited 228634 Normal pineal gland. H&E stain. LM X80. Melatonin is produced in the pineal gland and appears to play a major role in sexual development, hiberation in animals, metabolism and seasonal breeding.

11. Credit: © F.C. Skarva, MD/Visuals Unlimited 228649 Pancreas Islet of Langerhans and surrounding acinar cells. H&E stain. LM X100. The pancreas produces digestive enzymes and produces hormones, including insulin.

12. Credit: © SIU/Visuals Unlimited 212909 Pituitary gland.

13. Credit: © John Cunningham/Visuals Unlimited 98233 Taste bud. X68.