Accessory glands are specialized structures that support the main organs of a system. In the human body, these glands include the salivary glands, pancreas, and liver. They produce and secrete substances that aid in digestion, lubrication, and other essential functions. In the reproductive system, accessory glands such as the prostate gland and seminal vesicles contribute fluids that nourish and transport sperm. These fluids play a crucial role in reproduction by providing a medium for sperm mobility and protecting them during their journey.