front matter 1

ix

This book begins an Atlas Series on the

Development of the Human Central Nervous

System. We start with a volume devoted exclu-

sively to the spinal cord for two reasons: (1) The

spinal cord has similar structures throughout its

length so a complete picture of its development

at any specifi c age requires only a few different

levels–and in early stages, only a single level

is needed. (2) A transverse cutting plane is all

that is necessary to show spinal cord structures.

Thus, a single volume can feature all the stages

of spinal cord development. In contrast, many

different levels of the brain must be shown in a

variety of cutting planes to get an overview of

its structure at each stage of development. Four

additional volumes (in preparation) in the Atlas

Series will present a comprehensive picture of

the developing human brain cut in frontal, sagit-

tal, and horizontal planes. The second volume

will feature the third trimester; the third volume

will feature the second trimester; and fi nally, vol-

umes 4 and 5 will feature the late and early parts

of the fi rst trimester, respectively.

Our recent work on the developing spinal

cord (Altman, J., and S. A. Bayer, Development

of the Human Spinal Cord. An Interpretation

Based on Experimental Studies in Animals,

Oxford University Press, 2001) and this Atlas

are our fi rst publications linking developmental

studies of the central nervous system in animals

to humans. From the early 1960s to the present,

our work has featured the development of the rat

nervous system at the cell and tissue levels. We

use^3 H–thymidine autoradiography to gather a

large database that maps the stem cell mosaic in

the neuroepithelium, the times of origin of neu-

ronal populations within the nervous system, and

the migratory pathways of neuronal populations

as they settle in the maturing nervous system.

Our initial foray into human central nervous

system development began in the late 1980s

with a request from Serge Duckett to contrib-

ute a chapter on human central nervous system

development (Bayer, S.A., J. Altman, R. J.

Russo, and X. Zhang, Embryology, In: Pediatric

Neuropathology, S. Duckett, Ed., Lea & Febiger,

Philadelphia, PA, 1995, pp. 54-107). It was

while we were working on that chapter that we

realized how little is known about the develop-

ment of the human central nervous system. An

up-to-date interpretation simply does not exist.

PREFACE

The best work was published in German (Hoch-

stetter, F.: Beiträge zur Entwicklungsgeschichte

des menschlichen Gehirns. I. Teil. Vienna and

Leipzig, Franz Deuticke, 1919) and has never

been translated into English. There is a striking

similarity between the developing human and rat

central nervous systems. But Hochstetter did his

pioneering work on development when even the

mature anatomy of the nervous system was not

well understood. A re-examination of human

central nervous system development is needed

to link what has been learned from animal stud-

ies to normal development in humans. Medical

textbooks of human embryology are in need of

an update on central nervous system develop-

ment. In addition, the many disorders resulting

from abnormal neural development can be better

understood if normal development is better

known.

We decided to apply our knowledge of

rat nervous system development to humans by

directly examining histological sections of normal

human specimens. The National Museum of

Health and Medicine in the Armed Forces Insti-

tute of Pathology (AFIP), Walter Reed Hospital,

Washington D.C. has the Carnegie Collection of

human embryos and the Yakovlev Collection of

human fetuses; while we were there we acci-

dentally found the excellent Minot Collection

of human embryos. Unfortunately, attempts

to obtain funding for research at the AFIP

were unsuccessful, so we decided to fi nance

the research ourselves. During several trips to

Washington D.C. in 1996 and mostly during an

extended stay in the summer of 1997, we exam-

ined and took over 10,000 photographs of the

best preserved normal specimens in the Yakov-

lev, Carnegie, and Minot collections. All of the

fi lm developing was done by us. Technicians

were employed to scan each negative and create

high resolution digitized fi les. These fi les are

the sources for a comprehensive database on

the development of the human central nervous

system at the cell and tissue levels. This mate-

rial is being analyzed in our Laboratory of Devel-

opmental Neurobiology that is equipped with

photographic instruments, high resolution scan-

ners, printers, and Apple computers capable of

handling large fi les and running 3-dimensional

reconstruction software. This Atlas Series is the

result of our efforts.