Stromal

Stromal is an adjective deriving from stroma, the connective tissue framework that provides support and organization to organs. In most biological contexts, the stroma comprises the extracellular matrix and non-parenchymal cells, including fibroblasts, endothelial cells, pericytes, adipocytes, and immune cells, as well as blood vessels. It contrasts with the parenchyma, the functional cells of an organ or tumor.

In human anatomy and pathology, stromal tissue forms the structural scaffold within organs such as the liver, lung, and pancreas, and participates in wound healing and fibrotic responses. Stromal cells produce extracellular matrix components like collagen and elastin and influence tissue stiffness, vascularization, and signaling networks through cytokines and growth factors.

In cancer biology, the tumor stroma or cancer-associated stroma includes fibroblasts (often called cancer-associated fibroblasts), endothelial cells, immune cells, and ECM. The stroma interacts bidirectionally with malignant cells to affect growth, invasion, angiogenesis, and response to therapy. Treatments may target stromal components or the tumor-stroma interactions.

In plant biology, stromal is also used to describe the stroma of chloroplasts, the fluid matrix inside the organelle that surrounds the thylakoid membranes and contains enzymes of the Calvin cycle, including RuBisCO. The term can also appear in histology to describe supporting stromal tissue within organs such as the cornea.