The distribution, number, and certain neurochemical identities of infracortical white matter neurons in a chimpanzee (Pan troglodytes) brain

• Published in: Journal of comparative neurology (1911) 2021-10, Vol.529 (14), p.3429-3452
• Main Authors: Swiegers, Jordan, Bhagwandin, Adhil, Williams, Victoria M., Maseko, Busisiwe C., Sherwood, Chet C., Hård, Therese, Bertelsen, Mads F., Rockland, Kathleen S., Molnár, Zoltán, Manger, Paul R.
• Format: Article
• Language: English
• Subjects: Animal models; Animals; ape brain; Autism; Brain Chemistry; Calbindin; Calbindin 2 - metabolism; Calbindins - metabolism; Calretinin; Cell Count; Cerebral Cortex - chemistry; Cerebral Cortex - cytology; Cerebral Cortex - physiology; Cognitive ability; cortical evolution; Epilepsy; Female; Immunohistochemistry; Immunoreactivity; Interstitial cells; interstitial white matter neurons; Mental disorders; Models, Animal; Monkeys & apes; neurochemistry; Neurodegenerative diseases; Neurons; Neurons - chemistry; Nitric oxide; Nitric Oxide Synthase Type I - metabolism; Nitric-oxide synthase; Pan troglodytes - physiology; Parvalbumin; Parvalbumins - metabolism; Phylogeny; primate brain; RRID ‐ AB_10000321; RRID ‐ AB_10000340; RRID ‐ AB_10000343; RRID ‐ AB_11204707; RRID ‐ AB_91824; Schizophrenia; Substantia alba; Telencephalon; White Matter - chemistry; White Matter - cytology; White Matter - physiology
• ISSN: 0021-9967; 1096-9861
• DOI: 10.1002/cne.25202

We examined the number, distribution, and immunoreactivity of the infracortical white matter neuronal population, also termed white matter interstitial cells (WMICs), throughout the telencephalic white matter of an adult female chimpanzee. Staining for neuronal nuclear marker (NeuN) revealed WMICs throughout the infracortical white matter, these cells being most numerous and dense close to the inner border of cortical layer VI, decreasing significantly in density with depth in the white matter. Stereological analysis of NeuN‐immunopositive cells revealed an estimate of approximately 137.2 million WMICs within the infracortical white matter of the chimpanzee brain studied. Immunostaining revealed subpopulations of WMICs containing neuronal nitric oxide synthase (nNOS, approximately 14.4 million in number), calretinin (CR, approximately 16.7 million), very few WMICs containing parvalbumin (PV), and no calbindin‐immunopositive neurons. The nNOS, CR, and PV immunopositive WMICs, possibly all inhibitory neurons, represent approximately 22.6% of the total WMIC population. As the white matter is affected in many cognitive conditions, such as schizophrenia, autism, epilepsy, and also in neurodegenerative diseases, understanding these neurons across species is important for the translation of findings of neural dysfunction in animal models to humans. Furthermore, studies of WMICs in species such as apes provide a crucial phylogenetic context for understanding the evolution of these cell types in the human brain. Immunohistochemical staining for neuronal nuclear marker (NeuN) reveals the subcortical white matter neurons, or white matter interstitial cells (WMICs), deep to the gray matter of the temporal neocortex in the brain of a chimpanzee. GM—gray matter, WM—white matter, dashed line indicates the approximate GM/WM border.