A phagosome is a specialized structure formed within a cell during the process of phagocytosis, where the cell engulfs and internalizes particles, such as bacteria or dead cells. This membrane-bound vesicle contains the ingested material and is crucial for the immune response, allowing the cell to digest and eliminate harmful substances. Once formed, the phagosome typically fuses with another organelle called a lysosome, which contains digestive enzymes. This fusion creates a phagolysosome, where the ingested material is broken down and processed. This process is essential for maintaining cellular health and defending the body against infections.