The line of Gennari (also called the "band" or "stria" of Gennari) is a band of

myelinated Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be l ...

axons An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, th ...

that runs parallel to the surface of the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...

on the banks of the

calcarine fissure The calcarine sulcus (or calcarine fissure) is an anatomical landmark located at the caudal end of the medial surface of the brain of humans and other primates. Its name comes from the Latin "calcar" meaning "spur". It is very deep, and known a ...

in the

occipital lobe The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head". The occipital lobe is the vi ...

. This formation is visible to the naked eye as a white strip running through the cortical

grey matter Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distingui ...

, and is the reason the V1 in

primates Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

is also referred to as the "striate cortex." The line of Gennari is due to dense axonal input from the

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...

to layer IV of visual cortex. It is the name given to the enlarged external

band of Baillarger Bands of Baillarger, in neuroanatomy, are two myeloarchitectural structures, the external band of Baillarger and the internal band of Baillarger. These are myelinated fibers that course in the internal granular layer (layer IV) and internal pyrami ...

. The structure is named for its discoverer,

Francesco Gennari Francesco Gennari (born 4 October 1750 di Langhirano; died 4 December 1797) was an Italian anatomist. He is known for line of Gennari, a macroscopically white band seen in the cerebral cortex of the occipital lobe, which he observed on 2 Februar ...

, who first observed it in 1776 as a medical student at the

University of Parma The University of Parma ( it, Università degli Studi di Parma, UNIPR) is a public university in Parma, Emilia-Romagna, Italy. It is organised in nine departments. As of 2016 the University of Parma has about 26,000 students. History During the ...

. He described it in a book which he published six years later. Although non-primate species have areas that are designated primary visual cortex, some (if not all) lack a stria of Gennari.Zilles and Wree. ''Isocortex'' in Paxinos (Ed.) ''The Rat Nervous System'', 1985.

External links

Horizontal section of human brain showing line of Gennari from Polyak (1957)

References

Cerebral cortex Occipital lobe {{neuroscience-stub

See also

External links

References