Question

In the late nineteenth century, the histological examination of the central nervous system was dominated by Camillo Golgi’s reticular theory, which posited that nerve cells formed a continuous, syncytial network through which electrical impulses traveled without interruption. Golgi based this model on his proprietary black reaction (reazione nera), a silver chromate staining technique that selectively impregnated individual neurons. Paradoxically, Santiago Ramón y Cajal employed Golgi’s own staining method—with modifications involving double-impregnation—to arrive at a diametrically opposed conclusion: the neuron doctrine. Cajal demonstrated that neurons were discrete, individual entities contiguous rather than continuous with one another, separated by submicroscopic gaps later termed synapses.

Cajal’s success hinged on a crucial methodological insight: examining the developing nervous systems of embryonic and neonatal specimens rather than adult neural tissue. In mature brains, the dense, overlapping forest of fully developed axonal and dendritic arbors obscured individual cellular boundaries even under silver impregnation. By contrast, embryonic tissue presented sparse dendritic branching and unmyelinated axons, enabling Cajal to trace terminal nerve endings to their clear, unattached terminations. While Golgi interpreted the apparent fusion of nerve fibers in dense adult tissue as structural continuity, Cajal maintained that such appearances were optical artifacts resulting from the limitations of light microscopy when resolving closely apposed cellular membranes.

Consider each of the three choices separately and select all that apply.

Based on the passage, it can be inferred that Cajal’s investigation of neural structure differed from Golgi’s in which of the following ways?