This article is focused on Netrin1 factor and how it affects growth of axons in the embryonic spinal cords of mice. Netrin1 is found in both the floor plate of the spinal cord and in neural progenitors in the ventricular zone. This study aims to figure out which source of netrin1 is responsible for directing axon growth. They selectively removed netrin from different regions of the spinal cord. Used a control group, a Gli2 (key transcriptional regulator that transduces sonic hedgehog signaling) mutant group and a Gli2 and netrin1 double mutant in the floorplate and found that axon defects in netrin1 mutants don’t come from a loss of netrin1 in the floorplate. Next wanted to see if removing netrin1 in the ventricular zone would have the same effect on axon guidance. Their experiments showed that the axonal growth defects seen in the mutants were due to the loss of netrin1 in the ventricular zone and not the floor plate. Concluded that netrin1 derived from the ventricular zone works with laminin to act as a growth factor for the axons.
I thought the experimenters did a pretty thorough job in determining whether the ventricular zone or the floor plate was the source of the netrin1. They first tested its absence in the floor plate and then the absence in the ventricular zone. I would maybe try and find a way to make sure these experiments are replicable and maybe elaborate on the use of ECM factors such as laminin and collagen and its effects on axon extension talked about on page 9 of the article.