A BLOOD-DERIVED ATTACHMENT FACTOR ENHANCES THE INVITRO GROWTH OF 2 GLIAL-CELL TYPES FROM ADULT COCKROACH

Reactive glial cells from chemically-lesioned areas of the central nervous system (CNS) of adult cockroaches (Periplaneta americana) have been grown in vitro on a substrate of fibronectin. This paper reports the enhancement of growth that is achieved when blood cells, serum, or medium conditioned by a 2-h incubation with blood cells are used as an alternative substrate. Glial cells rapidly grew out from connective explants to form extensive radial mats of cells linking up with those from adjacent explants on each of the blood-derived substrates. In addition to supporting the growth of reactive glial cells, characterised by their long, thin, branching morphology, these substrates also revealed the presence of a second type of glial cell, not previously found on fibronectin. Such cells, derived from, ganglionic explants, behaved in a very different way to the reactive glia, initially spreading out to form a flattened sheet of phase-bright cells, before migrating away over the culture surface. The growth-enhancing effects of this blood-derived factor may play a role in the events following damage to the insect CNS, where it is known that the entry of blood cells into the lesion site is an important precursor to the rapid and structured repair seen in this system.