A DID system can be used for fax and voice mail as well as for live voice connections. Compared to regular PBX service, DID saves the cost of a switchboard operator, calls go through faster, and callers feel they are calling a person rather than a company.
Key Concepts: In dicotyledonous leaves there are two types of mesophyll cells, palisade mesophyll and spongy mesophyll. Palisade mesophyll cells form a layer beneath the upper epidermis whereas spongy mesophyll cells are internal to the lower epidermis.
Pigment tissue is a cellular connective tissue rather than a fibrous non-living connective tissue and has many melanin-containing connective tissue cells. It is found principally in the choroid and iris of the eye (Plates 303, 304 and 305).