Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which store and transport nutrients throughout the plant. In eudicots, pith is located in the center of the stem. In monocots, it extends also into flowering stems and roots. The pith is encircled by a ring of xylem; the xylem, in turn, is encircled by a ring of phloem.
Throughout the lymph node's interior are a series of street-like channels called sinuses that help guide the flow of lymph from the afferent lymphatic vessels, through the cortex and medulla, and finally to the efferent lymphatic vessels at the hilum.ach lymph node chain is responsible for draining a particular body region or structure. For example, the lymph node chains in your armpits drain your arms and upper chest, while the chains in your groin are responsible for filtering lymph from your feet, legs, genitals, and lower abdominal wall.
Lymph nodes are also known as lymph glands, or just glands, and form part of the lymphatic system. They are tiny, bean-shaped clusters of cells found in groups or chains throughout the body. Lymph nodes are the most important component of the immune system and within these glands, lymphocytes (immune cells) exist. Glands consist of lymphatic tissue surrounded by a capsule of connective tissue and are located in the armpits, on either side of the neck, inside the chest, abdomen, pelvis and in the groin.