Final answer:
Chromaffin cells are derived from the ectoderm germ layer, specifically from neural crest cells, and are responsible for producing catecholamines such as epinephrine and norepinephrine in the adrenal medulla.
Step-by-step explanation:
The embryonic origin of chromaffin cells is from the ectoderm germ layer. Specifically, these neuroendocrine cells develop from the neural crest cells. During the process of gastrulation in embryogenesis, the ectoderm forms and eventually gives rise to the neural crest. Chromaffin cells, which are found in the adrenal medulla, are considered unique postganglionic sympathetic neurons, and they are responsible for the production of catecholamines such as epinephrine and norepinephrine. These hormones are released into the systemic circulation as part of the sympathetic nervous system's response to stress.