ABSTRACT
This is the last volume in the Atlas of Human Central Nervous System Development series. It deals with human brain development during the early first trimester from the 3rd through the 7th gestational weeks (GW3-GW7). Volume 1 (Bayer and Altman, 2002) records the development of the spinal cord from GW4 to the 4th postnatal month. Volumes 2 through 5 deal with prenatal brain development. The analysis procedes in reverse (older-toyounger) order: from more recognizable brain structures in the third trimester to progressively less familiar structures in the second trimester to often uncertain or hypothetical structures in the first trimester. Volume 2 (Bayer and Altman, 2004a) records brain development during the third trimester, with specimens ranging in age from GW37 to GW26; its major theme is the maturation of the brain’s settled and enduring neuron populations. Volume 3 (Bayer and Altman, 2005) deals with brain development during the second trimester, with specimens ranging in age from GW24 to GW13.5; its major theme is the migration, sojourning, and settling of the brain’s diverse neuron populations. Volume 4 (Bayer and Altman, 2006) presents brain development during the late first trimester, with specimens ranging in age from GW11 to GW7.5; its major theme is the neuroepithelial mosaics that generate different populations of neurons and glia. This volume presents brain development during the early first trimester, with specimens ranging in age from GW7.0 to GW3.2, and has four major themes: (1) growth of the stockbuilding neuroepithelium along the expanding shorelines of the brain’s superventricles, (2) early neurogenesis, (3) the onset of brain parenchymal development related to the expansion and decline of the superarachnoid reticulum, and (4) the inductive and signaling interactions between the brain and peripheral structures in the skull.
