Zona glomerulosa (outer layer) envelops zona reticularis (inner layer) from the outside.

Erythropoiesis is the process of formation of RBC. Peptide hormone erythropoietin secreted from the juxtaglomerular cells of kidney stimulates erythropoiesis.

Pars intermedia of pituitary gland secretes only one hormone called Melanocyte Stimulating Hormone (MSH). This hormone causes dispersal of pigment granules in the pigment cells, thereby darkening the colour in certain animals like fishes and amphibians.

Calcitonin/thyrocalcitonin is a 32 amino acid, linear polypeptide hormone that is produced in humans primarily by the parafollicular cells of the thyroid gland. It checks excess $\mathrm{Ca}^{2+}$ and phosphate in plasma by decreasing mobilisation from bones. Deficiency of calcitonin results in osteoporesis or loss of bone density (due to dissolution of parathormone).

Thymosins play a major role in the development and differentiation of T-lymphocytes, which provide cell-mediated immunity. Thymosins also hastens attainment of sexual maturity.