Lymph node. Light micrograph of a section through the outer part of a lymph node. Beneath the fibrous outer capsule (blue, upper right) is a space called the subcapsular sinus (lighter area). This extends into a trabecular sinus which follows a trabecula (filament, blue, upper and bottom centre) deeper into the node. Tissue fluid (lymph) drains through the sinuses. Macrophages (purple cells within sinuses) filter debris from the fluid. They also collect and process antigens which are later presented to other immune cells, such as the B-lymphocytes which produce antibodies. Magnification unknown.