title: Neocortical neuronal morphology in the newborn giraffe (Giraffa camelopardalis tippelskirchi) and African elephant (Loxodonta africana).
abstract: Although neocortical neuronal morphology has been documented in the adult giraffe (Giraffa camelopardalis tippelskirchi) and African elephant (Loxodonta africana), no research has explored the cortical architecture in newborns of these species. To this end, the current study examined the morphology of neurons from several cortical areas in the newborn giraffe and elephant. After cortical neurons were stained with a modified Golgi technique (N = 153), dendritic branching and spine distributions were analyzed by using computer-assisted morphometry. The results showed that newborn elephant neurons were considerably larger in terms of all dendritic and spine measures than newborn giraffe neurons. Qualitatively, neurons in the newborns appeared morphologically comparable to those in their adult counterparts. Neurons in the newborn elephant differed considerably from those observed in other placental mammals, including the giraffe, particularly with regard to the morphology of spiny projection neurons. Projection neurons were observed in both species, with a much larger variety in the elephant (e.g., flattened pyramidal, nonpyramidal multipolar, and inverted pyramidal neurons). Although local circuit neurons (i.e., interneurons, neurogliaform, Cajal-Retzius neurons) resembled those observed in other eutherian mammals, these were usually spiny, which contrasts with their adult, aspiny equivalents. Newborn projection neurons were smaller than the adult equivalents in both species, but newborn interneurons were approximately the same size as their adult counterparts. Cortical neuromorphology in the newborn giraffe is thus generally consistent with what has been observed in other cetartiodactyls, whereas newborn and adult elephant morphology appears to deviate substantially from what is commonly observed in other placental mammals.
authors.affiliation: Laboratory of Quantitative Neuromorphology Department of Psychology, Colorado College, Colorado Springs, Colorado, 80903.
authors.forename: Bob
authors.initials: B
authors.lastname: Jacobs
authors.affiliation: Laboratory of Quantitative Neuromorphology Department of Psychology, Colorado College, Colorado Springs, Colorado, 80903.
authors.forename: Laura
authors.initials: L
authors.lastname: Lee
authors.affiliation: Laboratory of Quantitative Neuromorphology Department of Psychology, Colorado College, Colorado Springs, Colorado, 80903.
authors.forename: Matthew
authors.initials: M
authors.lastname: Schall
authors.affiliation: Department of Anthropology, Kent State University, Kent, Ohio, 44242.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Raghanti
authors.affiliation: Cleveland Metroparks Zoo, Cleveland, Ohio, 44109.
authors.forename: Albert H
authors.initials: AH
authors.lastname: Lewandowski
authors.affiliation: Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama, 36849.
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Kottwitz
authors.affiliation: Thompson Bishop Sparks State Diagnostic Laboratory Alabama Department of Agriculture and Industries, Auburn, Alabama, 36849.
authors.forename: John F
authors.initials: JF
authors.lastname: Roberts
authors.affiliation: Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, 10029.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Hof
authors.affiliation: Department of Anthropology, The George Washington University, Washington, DC, 20052.
authors.forename: Chet C
authors.initials: CC
authors.lastname: Sherwood
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D049229:Dendritic Spines; D004606:Elephants / Q000033:anatomy & histology*; D005260:Female; D000068276:Giraffes / Q000033:anatomy & histology*; D008297:Male; D019579:Neocortex / Q000166:cytology*; D009457:Neuroglia / Q000166:cytology; D009474:Neurons / Q000166:cytology* / Q000648:ultrastructure; D016622:Silver Staining
keywords: Golgi method; brain evolution; dendrite; morphometry; neocortex; nif-0000-10294