The endoplasmic reticulum is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum, and smooth endoplasmic reticulum. It usally has ribosomes attatched to it.
Lymphocytes are white blood cells that are part of the body's immune system
spongy bone is found in the bones of the skull, sternum, vertebrae, the pelvis, the lining of the marrow cavity and the epiphysis.