Control of Neuron Number and Stereology
The Control of Neuron Number
An Annual Review of Neuroscience article published with Karl
Herrup in 1988 that considers the roles of cell proliferation and death
on the control of neuron number. The perspective is primarily
evolutionary and developmental rather than molecular. How many neurons
are there in a human brain? Our updated estimate is an average of about
100 billion, of which 20 billion are neocortical and most others are
cerebellar granule cells.
Direct Three-Dimensional Counting
This paper by R. W. Williams and Pasko Rakic (1988) describes a novel
method to count cells in sectioned material. Direct three-dimensional
counting is related to the optical disector described in the same year
by Gundersen and colleagues. However, the method is actually an
adaptation of the counting brick method introduced by Howard and
colleagues in 1985. Unlike some variants of the disector, 3D counting
does not require the user to keep track of a sequential set of reference
and lookup planes, explicitly or implicitly. Counting rules are simple.
This paper has many details on the counting method, specific rules for
including and excluding cells, and details on setting up a
video microscope with Z-axis encoders and differential interference
contrast (DIC) optics. This is a substantial revision with corrections
and additions suggested (or motivated) by H. Gundersen, V. Howard, and
C. S. von Bartheld. Published in The Journal of Comparative Neurology.
QuickTime movie of a 3D counting box and please forgive the marginal
image quality of this first example. You can now also control one of our
Zeiss microscopes using the
iScope and view live video.
The Annotated Abercrombie
An annotated copy of M. Abercrombie's classic 1946 paper "Estimation of
Nuclear Population from Microtome Sections" published in The
Anatomical Record, volume 94. Abercrombie's entire text with figures
is reproduced. In this important technical paper Abercrombie describes
two methods to count cells in sectioned material: the well-known but
somewhat biased Method 1 and the neglected and entirely unbiased Method
2. Annotations are by R. W. Williams, June 1998.
Brain Volume Estimation from Serial Sections
A study by Drs. Glenn Rosen and Jason Harry provides a series of
guidelines for the estimation of brain volume from serial sections. They
find that the Cavalieri method provides better approximations under some
circumstances. However, this method does require equally-spaced
sections. They describe methods for the estimation of brain volume from
unequally-spaced sections, including an estimator based on the fitting
of piece-wise parabolic curves to sets of data.
Illustration of the Spanish Wildcat
by Michael Rothman from a review article in the New York Times.
Rapid Evolution of the Cat Visual System
An intriguing study that examines the cellular consequences of
evolutionary changes in brain size in the cat lineage (big-brained
wildcats versus small-brained domestic cats). Published in The
Journal of Neuroscience by R. W. Williams, Carmen Cavada, and
Fernando Reinoso-Suarez. This HTML edition includes several new figures.
This work was reviewed with moderate precision by The New York Times,
but was discussed most succinctly in News of the Weird.
Neuron Number in Fetal Monkey LGN
This paper, written with Pasko Rakic, summarizes data on the rise and
fall of neuron number in the dorsal lateral geniculate nucleus of rhesus
monkeys from early in gestation (E48) through to maturity. What is the
relationship between cell death in the lateral geniculate nucleus,
visual cortex, and retina? One unexpected finding was that the severity
of neuron death is extraordinarily high in the future magnocellular part
of the LGN. This paper was published in 1988 in The Journal of