Final answer:
Pheromone glands produce pheromones, which are chemical signals that affect the behavior and physiology of other members of the same species. They can attract mates, repel competitors, and influence social interactions and are detected by a specialized organ, the vomeronasal organ, in many animals, although their role in humans is less clear.
Step-by-step explanation:
Pheromone glands in animals produce chemical signals known as pheromones. These are not just ordinary scents but are specialized chemical messengers that influence the behavior and physiology of other individuals of the same species. Pheromones are typically associated with communication within a species, and they can elicit a variety of responses. For example, some may attract potential mates, while others may repel competitors, or even play a role in mother-infant bonding. Unlike other odors, pheromones generally do not reach the main olfactory bulb; instead, they are detected by the vomeronasal organ (VNO) in many animals, which sends signals to the brain by projecting to the amygdala and then to areas of the hypothalamus involved in reproductive physiology and behavior.
In humans, the presence and functional significance of the VNO are controversial, and the role of pheromones in human-to-human communication is still a subject of ongoing research.