The development of structure and function in the postnatal human cerebral cortex from birth to 72 months: changes in thickness of layers II and III co-relate to the onset of new age-specific behaviors.

HYPOTHESIS: The thickness of a cortical layer is a composite measure of neuronal, axonal, dendritic, synaptic, and glial numbers and sizes that may relate to thefunction of a cortical area. METHODS: 35 age-specific behaviors with defined cortical localization whose onset lies between birth and 72 months were selected. Each behavior's function localized to one or more of 12 cytoarchitectonic areas (Brodmann areas 4, with homuncular subdivisions for leg, trunk, face, and hand, plus 17, 18, 19, 20, 21, 24, 36, and 37). Data on cortical thickness for each layer of 41 cytoarchitectonic areas (including the 12 above) of the postnatal human cerebral cortex from birth of 72 months were analyzed for general patterns of change. For the 12 cortical areas functionally related to theage-specific behaviors, we searched for layer thickness changes that co-related to when the behaviors began. RESULTS: Without exception, all layers of the 41 cortical areas of the postnatal human cerebral cortex studied develop through a series of repeated thinning and thickening in a wave-like fashion. With regard to the co-relation of behavioral onset and changes in cortical layer thickness, from birth to 15 months, only layer II has agreater than expected frequency of being the layer with the greatest relative change in thickness (relative to its previous value). From 15 to 72 months, only layer IlI has a greater than expected frequency of being the layer with the greatest absolute change in thickness (81% involved a change in its direction of growth (thinning <--> thickening)). The co-occurrence of directional growth change and having the greatest layer thickness change were only statistically significant for layer III when an age-specific behavior began and was not seen for the 41 cortical areas overall (p = 0.014). CONCLUSIONS: Cortical laminar development exhibits aprocess that is mathematically consistent with a random walk with drift and with boundaries so that uncontrolled proliferation and pruning are prevented. The directional changes in layer growth could be controlled by feedback coupled with growth promoting and growth inhibiting factors. Layer II, with its function of establishing local corticocortical connections, appears to be most important in establishing age-specific behaviors of infants from birth to 15 months. Such a process tends to produce relatively simpler behaviors. LayerIII, with its function of establishing longer distance corticocortical connections, appears to be most important in establishing age-specific behaviors of children from 15 to 72 months. This process tends to produce richer, more cross-modal behaviors than those mediated primarily by local corticocortical interactions.

Approximate doubling of numbers of neurons in postnatal human cerebral cortex and in 35 specific cytoarchitectural areas from birth to 72 months.

From 1939 to 1967, J.L. Conel quantitatively studied the microscopic features of the developing human cerebral cortex and published the findings in eight volumes. We have constructed a database using his neuroanatomical measurements (neuronal packing density, myelinated large fiber density, large proximal dendrite density, somal breadth and height, and total cortical and cortical layer thickness) at the eight age periods (0 [term birth], 1, 3, 6, 15, 24, 48, and 72 postnatal months) he studied. In this report, we examine changes in neuron numbers over the eight age-points for 35 von Economo areas for which Conel gave appropriate data. From birth to 3 months postnatal age, total cortical neuron number increases 23-30%, then falls to within 3.5% of the birth value at 24 months, supporting our previous work showing that the observed decrease in the number of neurons per column of cortex under a 1-mm2 cortical surface from birth to 15 months is almost entirely due to cortical surface expansion. The present study also shows a 60-78% increase in total cortical neuron number above the birth value from postnatal ages 24 to 72 months. The generalization, to humans at least, of the finding of no postnatal neurogenesis in rhesus macaques, a species belonging to a superfamily that diverged from that of Homo sapiens more than 25 million years ago, is not warranted until explicitly proven for humans. The data of the present study support the existence of substantial postnatal neurogenesis in humans for the 35 cortical areas studied.

Quantitative microscopic anatomy, illustrated by its potential role in furthering understanding of the processes of structuring the developing human cerebral cortex.

In this study, we searched for patterns in selected, quantitative microscopic features of the developing postnatal human cortex for 35 cytoarchitectural areas at eight age points from birth to 72 months. These data come from the largest extant survey of the microscopic features of the developing postnatal human cerebral cortex (JL Conel, 1939-67). In contrast to Jacobson's proposal that cortical surface area increases in proportion to brain weight, Conel's data show that surface area increases as brain weight2/3, with the maximal rate of increase in both brain weight and cortical surface area occurring from 1 to 3 months. We computed the numbers of cortical neurons per cortical layer under 1 mm2 of cortical surface (neurons/layer per mm2 column) and divided these values by the total neuron number/mm2 column. For all areas, these data show plateaux in most of the layers for periods of months to years, often preceded and followed by changes in their neuron number in a sinusoidal fashion. The age points of the maxima and minima of such laminar values differ across the 35 cortical areas, indicating that their sinusoids are phase-shifted with respect to each other. Ranking the six layers in each area at each age point by their neuron number/layer per mm2 column shows that, by 72 months, the first areas to receive thalamic auditory or visual input (primary sensory and unimodal association cortices) have the most neurons in layer 4 and in either layer 3 or 6. In contrast, by 72 months, other areas have the most neurons in layers 3 and 6, with the primary motor cortex reaching this ranking earlier than any other area. For temporal and parietal association areas, layers 2 (short cortico-cortical connections) and 4 (thalamo-cortical connections) have the most neurons from birth to 6 months, whereas layers 3 (long cortico-cortical connections) and 6 (cortico-thalamic connections) have the most neurons by 72 months. The quantitative, statistically non-random patterns demonstrated by our analyses suggest that hierarchical correlations between such structural changes and age-specific behavioral acquisitions exist during the first 72 months of postnatal development.

Increased submucosal nerve trunk caliber in aganglionosis: a "positive" and objective finding in suction biopsies and segmental resections in Hirschsprung's disease.

OBJECTIVE: To establish the diagnostic usefulness of submucosal hypertrophic nerve trunk morphology in Hirschsprung's disease as a quantifiable parameter supportive of aganglionosis on hematoxylin-eosin-stained sections. DESIGN: We retrospectively evaluated size and density of submucosal nerves on hematoxylin-eosin-stained sections and S100 protein-stained sections of resected segments from 13 patients with Hirschsprung's disease, and in sections of 20 aganglionic and 50 ganglionic rectal suction biopsies. SETTING: All patients were seen at Childrens Hospital Los Angeles (Calif), a tertiary-care pediatric center; the age of patients at diagnosis or resection ranged between 2 days and 3 years. RESULTS: Aganglionic segments contain many distinct nerve trunks greater than 40 microm in diameter. Ganglionic segments/biopsies showed no nerve trunk larger than this threshold value (P approximately .0000). Nerve trunks of such caliber are rarely encountered in pathologic transition zones and sites of colostomy. CONCLUSIONS: Submucosal nerve trunks that are 40 microm or greater in diameter strongly correlate with abnormal innervation/aganglionosis. Use of this objective parameter in evaluating suction biopsies should be helpful in the morphologic diagnosis of Hirschsprung's disease in infancy and early childhood.

Evidence for a postnatal doubling of neuron number in the developing human cerebral cortex between 15 months and 6 years.

The generalization of the finding of no postnatal neurogenesis in non-human primates to humans may be incorrect because: (1) rhesus macaques belong to a superfamily that diverged more than 25 million years ago from the superfamily including the genus Homo; (2) the pulse thymidine labeling method, which demonstrates DNA synthesis rather than mitosis per se, is less reliable than some have assumed. This study examines changes in the number of neurons in a column underneath a cortical surface area of 1 mm2, extending through all cortical layers (mm2-column) for 35 gyri (representing about 73% of the human cerebral cortex) based on the data of J.L. Conel (1939 to 1967). We corrected these data, derived from his measures of cortical neuronal packing density, somal breadth and height, and cortical layer thickness at postnatal ages 0, 1, 3, 6, 15, 24, 48, and 72 months, for shrinkage and stereological errors. In all 35 gyri, neuron number/mm2-column: (1) initially declines (mu = 46% decline, sigma = 8%), 95% of which is due to surface area expansion (mean age of nadir value = 15.8 months); (2) then increases to age 72 months by 70% (mu = 1.7-fold increase, (mu rate = 1.1% per month). Because of a a concomitant 1.3-fold increase in cortical surface from 15 to 72 months, total cortical neuron number increases 2.2-fold. The close agreement between neuron number/mm2-column for Conel's age 72-month data to the corresponding values reported by others for adult human and primate cortex using more modern methods suggests the finding is not an artifact. Neuronal proliferative fate-determining factors provide at least four mechanisms for increasing cortical neuron number postnatally, with or without DNA synthesis.

Developmental patterns in the cytoarchitecture of the human cerebral cortex from birth to 6 years examined by correspondence analysis.

This paper uses correspondence analysis to examine the developmental patterns in the cytoarchitecture of the human cerebral cortex from birth to 72 months. The study is based on data collected by the late J. L. Conel, which consist of over 4 million individual measurements of six microscopic neuroanatomic features for each of six cortical layers in 46 cytoarchitecturally distinct regions. We analyze 1,727 profiles of development over eight age-points (term birth, 1, 3, 6, 15, 24, 48, and 72 postnatal months) resulting from the combinations of neuroanatomic feature, cortical layer, and brain cytoarchitectural region in the Conel data. The profiles for any given combination of feature and layer are found to be remarkably similar in all regions of the brain, and therefore the developmental patterns of different cytoarchitectural regions are not distinguishable from one another. Developmental change is most rapid at the earlier stages; of the total change in profile patterns observed, more than one-third occurs between birth and 6 months, about one-third occurs between 6 and 15 months, and less than one-third occurs between 15 and 72 months. The majority of the variance in developmental profiles is accounted for by the six microscopic, neuroanatomic features. Correspondence analysis shows that Conel's data are highly consistent and reliable.

Constructing the human cerebral cortex during infancy and childhood: types and numbers of cortical columns and numbers of neurons in such columns at different age-points.

This study examines JL Conel's data on neuron numbers in 35 human cortical areas for eight age points from 0 (birth) to 72 months, to analyze cortical columns, the presumed functional units of the cortex. For each cortical area at each age point, cortical surface divided by the square root of the area's neuron number gives cross-sectional areas with radii ranging from 180 microns at birth to 250 microns at 72 months. For the prefrontal cortex at birth and 48 months, these radii are approximately 2.10 and 1.19 times the longest radial basal dendrites, suggesting similar dimensions between these two measures of column radius. The logarithm of neuron number per cortical area and age point was examined in relation to the Weber-Fechner law governing the relationship between stimulus intensity and perception. A mechanism for this law consistent with the cortical model of Douglas et al. illustrates the importance of local circuit neurons. The cross-sectional areas of hexagonal columns for prefrontal cortex, using as radius, the longest radial extent of layer 5 pyramidal neuron basal dendrites, ranging from 0.013 mm2 at birth to 0.064 mm2 at 48 months, suggests that functional cortical columns increase cross-sectional area during development. These cross-sectional areas are 55-100-fold larger at birth, and 229-277-fold larger at 48 months, than those computed from somal width in prefrontal, layer 5 pyramidal neurons. Comparison of radial extent of pyramidal basal dendrites to their soma-to-soma distances shows that layer 3 pyramidal basal dendrites reach 1.5 and 4.0 other pyramidal neurons at 15 and 60 months, respectively, while layer 5, extra-large pyramidal basal dendrites reach 1.14 and 1.72 other such neurons at birth and 48 months, respectively. If such a relationship holds for other cortical areas, then the Conel data can be used to estimate basal dendrite extent, for which there currently is a paucity of data.

Reduced inferior olivary neuron number in early Down syndrome.

Counts of total neuron number per section and of neurons per microscopic field of inferior olivary principal nuclei were made on sections from 10 patients with Down syndrome (DS) aged 0.36 to 28 months and seven control (C) patients aged 1 to 29 months. After stereologic and appropriate shrinkage corrections of the count data, the ratios of values for DS/C were calculated. For mean principal olivary nucleus neuron number, DS/C = 0.64; for mean number of neurons per field, DS/C = 0.84; for mean volume of olivary neuronal band per section, DS/C = 0.79; and for mean volume of neuronal band per neuron, DS/C = 1.27. The data are in accord with other data suggesting that (1) numbers of cells in various cell populations, including various areas of the cerebrum, in DS approximate two-thirds normal (DS/C approximately 0.67); (2) for the volumes of such cell populations, DS/C = 0.82 normal; and (3) for volumes of individual cells, DS/C = 1.22 normal. The data of the present study suggest that the inferior olivary nuclei in DS are affected in the same way and to a similar degree as other brain areas, with the age distribution and histologic features of the specimens studied suggesting that the reduced olivary principal nucleus number in early Down syndrome results from reduced initial neuron production rather than postnatal neuron loss.

Familial renal tubular dysgenesis: a disorder not isolated to proximal convoluted tubules.

The autopsy findings of a newborn with renal tubular dysgenesis, born to first cousins of Moslim Arab descent, are described. Hypocalvaria and hyperflexible joints were noted in addition to the renal lesion. A microdissection study demonstrated marked shortening of all the nephron segments from the glomeruli to the collecting tubules, rather than an isolated abnormality of the proximal convoluted tubules.

Tay-Sachs disease with atypical chronic course and limited brain storage: alpha-locus hexosaminidase genetic compound.

A 19-year-old Irish-Jewish male had a slow neurologic regression starting at age 4 1/2 years with stuttering. The chronic course resembled that of Spielmeyer-Vogt (juvenile ceroid-lipofuscinosis) disease. The brain was atrophic with neuronal losses and huge compound inclusions in the remaining neurons. Lipid NANA was within normal limits in gray and white matter and GM2 gangliosides were moderately elevated at 11.5% lipid NANA. Beta-hexosaminidase A activity was reduced, secondary to a compound mutation at the alpha-locus. Lysosomal hydrolase activities and lipid composition showed nonspecific abnormalities. Exhaustive tissue extraction ruled out the possibility of tightly bound gangliosides to account for the relatively low GM2 ganglioside concentration. The extract contained unidentified chromogenic substances interfering with the resorcinol reaction. The similarly affected patient's sister lived to age 26 years and her brain was even more atrophic. No biochemical abnormality to account for progressive neuronal losses and relative lack of GM2 ganglioside storage was found.

Increased neutrophil respiratory burst in bcr-null mutants.

Philadelphia (Ph)-positive leukemias invariably contain a chromosomal translocation fusing BCR to ABL. The BCR-ABL protein is responsible for leukemogenesis. Here we show that exposure of bcr-null mutant mice to gram-negative endotoxin led to severe septic shock and increased tissue injury by neutrophils. Neutrophils of bcr (-/-) mice showed a pronounced increase in reactive oxygen metabolite production upon activation and were more sensitive to priming stimuli. Activated (-/-) neutrophils displayed a 3-fold increased p21rac2 membrane translocation compared with (+/+) neutrophils. These results connect Bcr in vivo with the regulation of Rac-mediated superoxide production by the NADPH-oxidase system of leukocytes and suggest a link between Bcr function and the cell type affected in Ph-positive leukemia.

Cardiomyopathy in childhood and adult life, with emphasis on hypertrophic cardiomyopathy.

Over 60 entries in the genetic catalog have cardiomyopathy features--32 autosomal dominant, 35 autosomal recessive and X-linked. Over 40 present in, or can have survival into, adult life. Major clinicopathologic categories of these cardiomyopathic disorders included: sudden death (13 entities); cardiac conduction disturbance important feature; associated myopathy or motor dysfunction; storage diseases with cardiac involvement; cardiac amyloidoses; and, other categories. Genes, abnormality of which can cause hypertrophic cardiomyopathy (HCM), have been identified on chromosomes 1, 14 and 15, the locus on chromosome 14 involving the B-myosin heavy chain gene, but at least one unidentified locus is known to exist and there is a suggestive locus on chromosome 16, so that HCM is not a single disease but a group of disorders with clinicopatholopic similarities. To investigate these aspects of HCM in some detail, sixty-six patients with "sharply demarcated" differential myocardial fiber bundle hypertrophy (DMBH), considered to be of significant degree, from a pediatric autopsy data base of approximately 8,000 cases, were reviewed. Twenty-three of the patients died suddenly, without antecedent significant cardiac dysfunction, seven had clinical congestive heart failure of varying duration, three were stillborn, six showed evidence of aspiration of amniotic sac content (three had history of fetal distress), five had ischemic bowel disease, three (two with clinical cerebral palsy and one with Ondine's curse syndrome) had cerebral atrophy and sclerosis and one had extensive more acute encephalomalacia, and a variety of other major "causes of death" were present. Whether all infants and children with DMBH meeting the criteria used, who do not have congenital heart disease, have dominant hypertrophic cardiomyopathy (HCM) cannot be established by studies of this type, but the "concentration" of a gene or genes for HCM in pediatric autopsy series because the strong effect of HCM on life expectancy is relevant to this possibility. The data raise the question that stillbirth, fetal distress with aspiration of amniotic sac content, ischemic bowel disease and cerebral atrophy and sclerosis may be hitherto underappreciated features of HCM in childhood, and that patients with HCM may be peculiarly liable to die with certain types of septic shock, such as acute meningococcemia. In the material of this study, sudden death was statistically more frequent in females than in males in childhood (p < .029).

Labeled lectin studies of renal tubular dysgenesis and renal tubular atrophy of postnatal renal ischemia and end-stage kidney disease.

Renal tubular dysgenesis (RTD), with hypoplasia especially of renal proximal convoluted tubules and clinical neonatal anuria or oliguria, has been reported as a congenital familial (autosomal recessive) disease, variably with features of oligohydramnios, Potter syndrome, or pulmonary hypoplasia. A similar tubular lesion due to antenatal tubular atrophy has been reported for conjoined twins with twin-twin transfusion syndrome or acardia and in infants of mothers given antihypertensive agents, including angiotensin-converting enzyme (ACE) inhibitors, during pregnancy, and it has been seen as a unilateral lesion in young infants with renal artery stenosis due to arteritis or medial arterial calcinosis. The renal tubular changes in RTD are very like those of the "endocrine kidney" in experimental animals and resemble those of the renal tubular atrophy of end-stage kidney diseases such as glomerulonephritis, tubulointerstitial kidney disease, obstructive uropathy/pyelonephritis, graft rejection of transplanted kidneys, or the renal parenchymal changes seen with protracted dialysis therapy. Labeled lectins that differentially mark proximal convoluted, distal convoluted and connecting, and collecting tubules showed no distinctive differences in staining patterns of the hypoplastic renal tubules of infants and children with RTD, postnatal renal artery obstruction, or the various types of end-stage renal disease with the lectins used (PNA, GSLI, UEA, and LTA). The findings suggest that the renal tubular changes in some if not all the conditions studied are the result of renal ischemia. The reported familial RTD with hypernephronic nephromegaly may be a specific disorder, but other forms could reflect renal ischemia acquired in utero or in early or later postnatal life.

Syndromal associations of common origin of the carotid arteries.

The term "common origin of the carotid arteries" (COCA) has been proposed to replace the older terms "origin of the left carotid artery from the innominate stem" and "bicarotid trunk with anomalous right or left subclavian artery." These anatomic patterns are usually reported to occur in about 11% of whites and 20-25% of blacks and have been reported to have increased frequency in patients with esophageal atresia-tracheoesophageal fistula, DiGeorge anomaly, and anomalous origin of the left coronary artery from the pulmonary artery. COCA is a significant, if not invariant, feature of the great arteries in the condition usually called in the more recent literature "anomalous origin of the innominate artery," the most frequent cause of symptomatic tracheal compression by anomalous systemic arteries. Analysis of associations of COCA with various other congenital cardiovascular lesions showed, in addition, significant association with congenital polyvalvular disease, truncus arteriosus, aorticopulmonary window, trisomy 13, 18, and 21 syndromes, acrocephalosyndactyly (especially Apert syndrome), tetralogy of Fallot not associated with DiGeorge anomaly, and clinical Noonan phenotype. Pentalogy of Cantrell was associated with no increase in incidence of COCA.

Branching patterns of right pulmonary artery in cardiovascular anomalies.

The branch of the right pulmonary artery (RPA) to the upper lobe of the right lung (RUL), the truncus anterior of the RPA, and the pars anterior of the left pulmonary artery, which supplies the left upper lung lobe (LUL), were demonstrated by both dissection of postmortem specimens and angiography for 20 infants and children, by angiography only for 57, and by specimen dissection only for 59 (total 136). In posteroanterior angiograms, the RUL artery branches from the RPA near the right lateral border of the vertebral column, while the LUL artery or arteries arise more laterally, near the left midclavicular plane. This pattern is reversed in situs inversus (eight patients studied). Thirty-nine patients in other categories of congenital cardiovascular disease showed an abnormal RUL or LUL arterial pattern, including pulmonary isomerism, right lung type (RUL artery pattern present bilaterally, 12 patients); pulmonary isomerism, left lung type (RUL artery pattern absent bilaterally, 11 patients); scimitar syndrome (RUL artery pattern normal, 1 patient; absent bilaterally, 4 patients); and left pulmonary artery sling (RUL artery normal, one; hypoplastic, one; absent, two patients). Five patients with tetralogy of Fallot (TOF) with right aortic arch (RAA) and 1 of 15 with RAA not TOF or situs inversus showed a relatively large RUL artery arising more laterally than usual. Three of six patients with double outlet right ventricle had the LUL artery larger than usual plus two accessory RUL arteries, and one patient with crossed pulmonary arteries showed a similar pattern. Two patients with single ventricle had an RUL artery of normal pattern although the RUL bronchus was absent, and one patient with single ventricle and situs inversus had a comparable pattern in the left lung. The ease of demonstration of the right and left upper lobe branches of the pulmonary artery by dissection or angiocardiography warrants greater attention to their patterns in patients with congenital cardiovascular disease. Dissociation of upper lobe bronchial and vascular patterns is unusual and may also be of diagnostic value.

Studies of the enteric nervous system in Alzheimer disease and other dementias of the elderly: enteric neurons in Alzheimer disease.

Studies of the myenteric (Auerbach) plexus of esophagus, stomach, small intestine, colon, and rectum, by microdissection and pointcount morphometry, for 18 patients with Alzheimer disease (AD), eight with other types of dementia of the elderly, non-demented elderly patients, and younger control patients, show a normal loss of enteric neurons and plexus mass with age, comparable to that reported by others for rats and guinea pigs. Values for patients with AD or other non-AD dementias did not differ from those for elderly controls. Enteric neurons in AD or the other dementias studied showed no definite stain with ALZ-50, a monoclonal antibody to a derivative of the microtubule-associated protein tau, which stains degenerating cerebral neurons in AD. Although the processes in the central nervous system in AD affect some neurons derived from the neural plate, the results of this study suggest that the enteric neurons, which are of neural crest origin, are not affected in AD. Enteric neurons, at least by the methods of this study, do not provide a useful peripheral marker for AD.