They are all the same kind of cell, just found in different locations. This kind of dendritic cell is formed in the bone marrow along with all the other blood cells. Follicular dendritic cells are cells that facilitate antigen recognition by B cells in follicles. This kind of dendritic cell is not bone marrow derived and is not a kind of blood cell. It is purely a resident of the follicles of secondary lymphoid organs.
B cells form germinal centers around follicular dendritic cells in lymphoid organs.
We will cover T cell maturation in the thymus later. The thymus functions maximally during fetal development and in childhood. Whereas it is a relatively large organ at the time of birth with an average size of 70g, by age 60 its size shrinks to about 3 g. These are all characterized by the presence of follicles. Primary follicles are a small network of follicular dendritic cells and non-activated B cells.