The Corpus Callosum
 |
We have been trying to develop a quantitative index of fetal brain development by measuring a structure called the corpus callosum or 'CC' (which means 'hard body' in Greek). The CC is referred to as a 'commisure' -a conduit for axons of berve cells within the brain to connect with similar cells on the other side of the brain. The cross sectional area of the CC, is an indicator of the number of neurons making up the brain! The size and shape of the CC are markers of the way the brain is developing. The CC will bulge in places where neuron density is too high and contracted where there has been a focal, abnormal loss of cells. There are developmental syndromes in which the corpus callosum does not form. Since the CC is the main commissure of the brain, its absence can be associated with significant functional impairment. |
The
red "comma" is the nerve fiber portion of the corpus
callosum in this image of the middle of the brain. CC's are visibly smaller than average with trisomies 13, 18, and 21 (Down's
syndrome) early in gestation, corresponding to delayed brain growth. We are hoping to learn more about the natural
history of fetal brain development - when do things happen and what external
factors might influence the way that process occurs? The importance of the timeline for all aspects of development has been the subject of many years of study by Dr Shraga Rottem, founder of the Ironfan (International Registry of Fetal Anomalies). |
 |
 |
The
surface of the cerebral hemispheres is very smooth for at least the first
half
of gestation. One of the main features of brain growth in the third trimester
is a marked increase in surface area, as parts of the surface pucker
out (the
gyri) separated by grooves ( sulci). This image is a phase reversed 3D ultrasound view of
the outside of the parietal lobe of the brain of a normal 34.6 week
boy. The gyri and sulci are very well defined. Brain growth can be accelerated
late in pregnancy with stressful conditions that predispose to early delivery. Delayed sulcation is a very serious indicator of abnormal development;
the most extreme form is an entirely smooth brain with no gyri or sulci
is referred
to as "lissencephaly". |
| [Up] | The 24 Hour Plan |
| [Home] | Home Page |
| [Mail] | Send EMail to AmnioNet |
| [Contents] | AmnioNet Contents |