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.
Best Answer: Mesophyll tissue forms the bulk of the leaf. It makes up the green tissue of the leaf and consists of thin-walled cells containing chloroplasts (bits that contain the chlorphyll). In most dicot leaves the mesophyll is differentiated into palisade parenchyma and spongy parenchyma.