The formation of synaptic contacts in human cerebral cortex was compared in two cortical regions: auditory cortex (Heschl's gyrus) and prefrontal cortex (middle frontal gyrus). Synapse formation in both cortical regions begins in the fetus, before conceptual age 27 weeks. Synaptic density increases more rapidly in auditory cortex, where the maximum is reached near postnatal age 3 months. Maximum synaptic density in middle frontal gyrus is not reached until after age 15 months. Synaptogenesis occurs concurrently with dendritic and axonal growth and with myelination of the subcortical white matter. A phase of net synapse elimination occurs late in childhood, earlier in auditory cortex, where it has ended by age 12 years, than in prefrontal cortex, where it extends to midadolescence. Synaptogenesis and synapse elimination in humans appear to be heterochronous in different cortical regions and, in that respect, appears to differ from the rhesus monkey, where they are concurrent. In other respects, including overproduction of synaptic contacts in infancy, persistence of high levels of synaptic density to late childhood or adolescence, the absolute values of maximum and adult synaptic density, and layer specific differences, findings in the human resemble those in rhesus monkeys.

Deposits in macular human Bruch's membrane (BrM) increase with age and have been postulated to be associated with age-related maculopathy. We used two ultrastructural methods to compare these deposits by electron microscopy in macular and peripheral BrM of eight eyes from donors 63-86 years of age. Quick-freeze/deep-etch (QFDE) was used to prepare replicas that showed the ultrastructure of deposits, and osmium-tannic acid-paraphenylenediamine (OTAP) was used to preserve small extracellular lipid particles. We found that an accumulation of lipoprotein-like particles (LLPs) occurred in the peripheral BrM just as it does in the macular region, but with perhaps a somewhat slower time course. The "lipid wall," reported in macular BrM, was also found occasionally in the peripheral regions. The same processes that lead to age-related accumulation of LLPs in macular BrM appear to also occur in the peripheral regions.

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In the hepatocytes of 'normal' fetal mice from mothers which were carriers of muscular dysgenesis, catalase and D-amino acid oxidase (DAAO) positive as well as negative peroxisomes were observed. DAAO reaction product was occasionally localized in patches around cell membranes and DAAO-positive peroxisomes were frequently observed near mitochondria.