Fetal Gyral Development

During the first half of gestation, the human fetal brain has a smooth surface.  At about 20 weeks gestation, the brain begins to form the bumps (gyri) and grooves (sulci) that are typical of the adult brain, averaging about 1 sulcus per week of gestation after 20 weeks.  The brain of this 25 week gestation... Continue Reading →

Cortical Atrophy in an Elderly Person (90 years old)

A normal adult loses about 0.2% of brain volume every year after middle age.  Compared to young and middle-aged adults, the brains of the elderly have comparatively widened sulci, narrowed gyri, a thin cortical ribbon, and enlarged ventricles due to progressive brain volume loss, which, clinically, may contribute slower processing speed for cognitive tasks and other changes.  Microglia-mediated synaptic pruning and other etiologies for decreasing cortical volume in the... Continue Reading →

Dorsal Root Ganglia

Dorsal root ganglia are located along the length of the spinal cord and are composed of clusters of large neuron cell bodies, each with a prominent nucleus and nucleolus, that belong to sensory nerves whose axons deliver sensory information to the spinal cord.

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