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.

Age Factors↗

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Incidence of short trachea in patients with myelomeningocele.

Short trachea, typically due to reduced tracheal cartilage ring number, produces high tracheal bifurcation which can be demonstrated in radiographs with evaluable air bronchograms. Accidental bronchial intubation with sequelae has been reported in short trachea patients who have tracheal intubation. Short trachea is associated with a number of syndromes, including DiGeorge anomaly and several types of congenital heart disease and skeletal dysplasias. Review of chest radiographs of 87 patients with myelomeningocele revealed that 31 (36%) had short tracheas. Two patients had a total of 3 episodes of bronchial intubation. This degree of association of short trachea with myelomeningocele, the frequency of myelomeningocele, and the number of surgical procedures performed on many such patients suggest that special attention to the short trachea is warranted in myelomeningocele patients because of the risk of accidental bronchial intubation and subsequent sequelae. Twelve (14%) of the myelomeningocele patients lacked radiographic evidence of the presence of twelfth ribs and 11 (13%) had hypoplasia of the twelfth ribs.

Adolescent↗

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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.

Aging↗

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Yellow-orange intervertebral disks in chronic obstructive jaundice in children.

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Biliary Atresia↗

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Tracheostenosis and bronchial abnormalities associated with pulmonary artery sling.

Three patients with aberrant left pulmonary artery (sling artery) are reported to illustrate associated tracheobronchial abnormalities. The clinical picture was that of severe episodic or progressive respiratory distress without dysphagia in early infancy. Striking narrowing of the trachea by complete "ring cartilages," unrelated to compression by the abnormal pulmonary artery, was present. Tracheotomy and intubation failed to relieve the obstruction. In one patient the bronchi and bronchial segmentation pattern were normal, but in the other two patients, bronchial abnormalities included wide irregular cartilages in the main bronchi, forming more complete rings than is normal. In both, the right main bronchus was relatively longer than normal, and the bronchus intermedius showed poor cartilage ring formation and was relatively short compared to the main bronchus. This discrepancy did not appear to be due to distal displacement of the right upper lobe bronchus. In these two patients the left main bronchus was relatively short and wide with reduced number of cartilage rings (five-six vs usual normal number of nine), so that the right and left main bronchi were almost of equal length. However, the branch patterns of the lobar bronchi were within normal range. Bronchoscopy seems essential to demonstrate such ring tracheal cartilages (absence of the pars membranacea of the trachea), which when found should alert the examiner to the possible presence of an abnormal left pulmonary artery. Since surgical correction of tracheal stenosis of this type is not possible at present, the ultimate prognosis of patients with sling artery may depend more on the severity of the tracheal anomaly rather than on success of surgical correction of the abnormal left pulmonary arterial course. Although aberrant (sling) left pulmonary artery can occur in patients without respiratory tract symptoms, tracheal stenosis due to ring tracheal cartilages occurs in a significant fraction of patients with this arterial anomaly. Bronchoscopic study of the trachea, and possibly air or contrast bronchography of right and left main bronchi, can be of aid in diagnosis of this complex.

Bronchi↗

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Fibrous histiocytoma of the trachea.

Intratracheal tumors are rare in children. A case is reported of a two-year-old female child with a fibrous histiocytoma of the trachea which caused severe respiratory obstruction and persistent right middle lobe pneumonia. Fibrous histiocytomas are basically benign tumors of histiocytes and have been mistaken for other tumors such as fibroma, sclerosing hemangioma, neurilemoma, fibromatosis, hemangiopericytoma, fibrosarcoma, and some primitive sarcomas. Fibrous histiocytomas have not been reported in the trachea or bronchi. The patient was treated with endoscopic removal of the tumor, and has remained free of disease to this date.

Child, Preschool↗

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Lymphomatoid granulomatosis in a child with acute lymphatic leukemia in remission.

Lymphomatoid granulomatosis, a tumor-like process of unknown etiology, produced progressively destructive disease of the larynx, trachea and bronchi in an eight-year-old girl with acute lymphoblastic leukemia of five years duration. The leukemia had been in remission for 4 1/2 years at the clinical onset of the lymphomatoid granulomatosis. Whether this occurrence suggests that lymphomatoid granulomatosis is a type of neoplasm, or is associated with immunologic depression, cannot be stated. Fortunately rare, and of poor prognosis, the disorder may become more frequent with improved survival rate of patients with leukemia and other neoplasms.

Child, Preschool↗