A class of biological cells distinguished by characteristic structure, function or molecular state. Comparing mixed biological tissues can confound changes within a cell type with changes in the abundance of that class.

Cell adhesion is attachment of a biological cell to another cell or to its surroundings through molecular interactions. Adhesion strength and turnover help determine how cells transmit forces and rearrange.

A leukocyte, or white blood cell, is a biological cell involved in immune defence. The category includes lymphocytes and cells such as macrophages and neutrophils, whose recognition and effector mechanisms differ. Many leukocytes circulate in blood but act within tissues, so a blood count samples only part of their distribution. Unlike the name might suggest, the category describes cellular identity rather than requiring a visibly white individual cell. ^[ref]

The endomembrane system comprises functionally connected internal membranes such as the endoplasmic reticulum, Golgi apparatus, endosomes and lysosomes, together with their transport carriers. Connections through carrier traffic differ from direct continuity of the membrane sheets.

Partition of one cell into descendant cells. Copying and allocating inherited material must be coordinated with physical separation, but nuclear division and cytokinesis are distinct events.

A cell participating in an organised epithelial layer, with context-dependent polarity, adhesion and barrier or transport functions.

An increase in cellular biomass or size. It differs from cell proliferation, which increases the number of cells.

A connective-tissue cell with roles in extracellular matrix production and tissue organisation. Fibroblast biological populations and activation states are heterogeneous.

A fibroblast in a tumour-associated state. Some functions support tumour progression while other fibroblast biological populations or functions can restrain it; the label alone does not establish the causal effect.

An innate immune cell that can phagocytose material and regulate tissue and immune responses. Its behaviour varies with local signals and cellular history.

A macrophage within or associated with a tumour microenvironment. Its contribution to invasion, vascular remodelling or immunity depends on the particular functional state.

A cell lining a blood or lymphatic vessel. Endothelial state influences barrier function, perfusion and interactions with circulating cells.

A T-cell biological population with immune-suppressive functions that can restrain both pathological inflammation and antitumour responses.

A myeloid biological population defined partly by its ability to suppress immune responses, particularly in disease-associated settings such as cancer.

An antigen-presenting immune cell that can help initiate T-cell responses. Antigen uptake alone does not establish effective activating presentation.

A lymphocyte using a T-cell receptor for antigen recognition. Distinct biological populations have cytotoxic, helper, regulatory and memory functions.

A stromal cell of the pancreas that can adopt activated states and contribute to extracellular matrix and metabolic interactions in pancreatic disease.

A lymphocyte recovered from within a tumour specimen. Presence in a specimen does not alone establish effective recognition or killing of malignant cells.

A B lymphocyte belongs to the antibody-producing lineage of the adaptive immune system. Recovery of an antigen-binding clone does not alone establish a useful therapeutic antibody or an immortal production line.

A myeloma is a malignancy of the plasma-cell lineage. Selected cultured myeloma lines provide an immortal fusion partner in hybridoma production; their metabolic selection properties depend on the particular line.