chapter  1
5 Pages

I. INTRODUCTION -----------------------------------------------------------------------

This Atlas focuses on the development of the human spinal cord, and is the fi rst volume in the series, Atlas of Human Central Nervous System Development. The largest sections of this Atlas feature photographs of transversely cut spinal cords from normal specimens ranging in age from gestational week (GW) 4.0 up to and including the 4th postnatal month. The fi rst trimester is described in Part II, the second in Part III, the third in Part IV, and the postnatal period in Part V. Each specimen or set of specimens is introduced by an overview plate that shows thumbnail photographs of all sections in that part of the Atlas at the same scale. The overview plate is followed by companion plates designated as A and B on facing pages. The A part of each plate on the left page shows the full contrast high magnifi cation photograph of the specimen without any labels; the B part of each plate on the right page shows a low contrast copy of the same photograph with superimposed outlines and unabbreviated labels. Part VI presents 3-dimensional reconstructions of the cervical spinal cord during the fi rst trimester (VIA) and of motoneuron columns in the ventral horn at cervical, thoracic, and lumbar levels in three specimens at the end of the fi rst trimester and the beginning of the second (VIB). In Part VII, quantitative summaries of spinal cord development are presented in several graphs along with estimates of timetables for neurogenesis, dates of cell migration and settling, and sequences of myelination in major fi ber tracts. A Glossary gives brief defi nitions for each label in the Plates, and defi nes other terms that are used in notes and fi gure captions. The concepts presented here are based on Altman and Bayer (2001), a research work that links human spinal cord development to the large body of developmental experiments in animals.