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.
Basic Tissue Types. All of the various tissues of the human body can be categorized into four basic tissue types. All organs are built of these four tissues, which have consistent characteristics and arrangements from organ to organ. The parenchyma of the brain is nervous tissue (nerve cells and glia). 2  The blood vessels within the brain and the connective tissue associated with these blood vessels are stroma. 3  The parenchyma of the malignant neoplasm is cancer cells. 4  Other tissues, including blood vessels, which grow to support the tumor are stroma.