(2012) for further reading on obesity and perilipins. In cells specialized mechanism, in which cells of one type release molecules into the inter-
for lipid storage, the vacuoles reach 80 µm or more in diameter. They stitial fluid of the local environment, to be detected by nearby cells of
function as stores of chemical energy, thermal insulators and mechani- a different type that express the specific receptor protein. Neurocrine
cal shock absorbers in adipocytes. In many cells, they may represent cell signalling uses chemical messengers found also in the central
end-products of other metabolic pathways, e.g. in steroid-synthesizing nervous system, which may act in a paracrine manner via interstitial
cells, where they are a prominent feature of the cytoplasm. They may fluid or reach more distant target tissues via the blood stream. Cells
also be secreted, as in the alveolar epithelium of the lactating breast. may generate and respond to the same signal. This is autocrine signal-
ling, a phenomenon that reinforces the coordinated activities of a group
Transport across cell membranes of like cells, which respond together to a high concentration of a local