Types discussion: Autism (a developmental brain disorder characterized by impaired social interaction and communication skills, and limited range of activities and interests) is the most characteristic and best studied PDD.
A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of the plant and keep the plant growing.hese secondary meristems are also known as lateral meristems because they are involved in lateral growth. At the meristem summit, there is a small group of slowly dividing cells, which is commonly called the central zone.
The meristem also forms a protective root cap. The cells to the upper left of this image are embryonic protoderm, ground meristem, and procambium. Apical meristems are sites of intense mitotic cell divisions. The new cells produced fuel the growth and development of new tissues. second ring of meristematic tissue forms just below the epidermis in woody plants to produce bark. This is the cork cambium. The cork cambium and vascular cambium contribute to subsequent or secondary growth typically found only in woody plants. Now, roll over the apical meristem on the diagram..