The glands that secrete hormones comprise the endocrine signaling system. The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell (autocrine or intracrine signalling) or nearby cells (paracrine signalling).
A fen is one of the main types of wetland, the others being grassy marshes, forested swamps, and peaty bogs. Along with bogs, fens are a kind of mire. Fens are usually fed by mineral-rich surface water or groundwater.
slough-a hollow filled with mud. bog, peat bog-wet spongy ground of decomposing vegetation; has poorer drainage than a swamp; soil is unfit for cultivation but can be cut and dried and used for fuel.lough 1. A usually low-lying area of soft waterlogged ground and standing water: bog, fen, marsh, marshland, mire, morass, muskeg, quag, quagmire, swamp, swampland, wetland.