TABLE 3.

Studies visualizing VENs using Golgi staining.

Studies	Subjects used for Golgi staining	Region and cortical layer in which VENs were analyzed	Golgi staining method	VEN soma morphology	VEN apical dendrite/stem morphology	VEN basal dendrite/stem morphology	VEN axon morphology
Cajal, 1899	1-month-old human female	FI; layer V	Classic Golgi staining	Spindle-like	Prominent with gradual decrease in thickness	Prominent, ends with a dendritic tuft (basilar skirt)	Arises from basal stem/dendrite
Watson et al., 2006	23-year-old human male	ACC and FI; layer V	Modified Golgi technique	Large and elongated, clear demarcation between soma and dendrites is visible in some neurons	Prominent, no additional dendrites or branching for a half-soma’s distance along the length of the proximal dendrites	Prominent, no additional dendrites or branching for a half-soma’s distance along the length of the proximal dendrites, most neurons shown lack a basilar skirt	Not shown
Evrard et al., 2012	One rhesus macaque	Anterior insula; layer Vb	Rapid Golgi-Cox	Spindle-like	Branches distally into several thinner spiny dendrites	Branches into thinner spiny dendrites in layer VI, visible basilar skirt	Arises from basal dendrite
Butti et al., 2014	One female pygmy hippopotamus	ACC, frontal magnocellular cortex, lateral gyrus*; layer V**	Modified rapid Golgi	Stout, sometimes slender	Almost as thick as the soma	Almost as thick as the soma, occasionally dividing into two branches with a hint of a basilar skirt	Not shown
Banovac et al., 2019	5 adult human male subjects	ACC; layer Vb	Rapid Golgi and Golgi-Cox	Large spindle-like, stick-like or corkscrew-like, on most neurons there is no clear demarcation between soma and dendrites	Very thick origin (up to 8 μm), very gradual decrease in thickness	Constant or very gradual decrease in thickness, low bifurcation degree, but high arborization (brush-like basilar skirt)	Arises from end of basal stem/dendrite
Correa-Júnior et al., 2020	4 adult human subjects (two male and two female)	ACC; layer Vb	“Single-section” Golgi	Large, elongated and spindle-shaped	Prominent with gradual decrease in thickness	Prominent with gradual decrease in thickness, low bifurcation degree, level of arborization depends on subtype (basilar skirt present in some neurons)	Not shown

*Other cortical areas were also analyzed, but only using Nissl staining or immunohistochemistry (frontopolar, temporal, parietal, and occipital cortex) and VENs were claimed to be found in all the analyzed cortical regions.

**VENs were claimed to occasionally have been found in the deep layer III of numerous cortical areas, but they were still most abundant in layer V and shown on Golgi only in layer V.