3D computerized reconstruction of the human embryonic lens

1
3D Computerized Reconstruction of The Human
Embryonic Lens Scholar(s) Luis Noboa , Jih-Shu
Ruey. Mentor(s) Dr. Richard Hendrix, Dr Joel
Hernandez Borough of Manhattan Community College
Abstract
Discussion
We are developing an efficient way to measure
the geometric properties of human embryonic
ocular lenses by means of computer aided design.
Specifically, a new software program called
WinSURF is being tested for its ability to
provide us with more accurate numerical
measurements at greater speed. We are working
with serially sectioned human eye specimens from
the Carnegie Collection kindly donated by the
National Museum of Health and Medicine. The
Materials come to us as digitized serial
micrographs of entire human embryos between
stages 10 (circa 20 days post conception) and 17
(circa 50 days post conception). These serial
sections are aligned and subjected to 3D
computerized reconstruction using the WinSURF
modeling system, which produces 3D virtual images
of staged human ocular lenses. Linear, surface
and volume measurements will constitute the
geometric data. Analysis of this data will allow
us to compare the geometrodynamics of human
ocular lens development with previous research on
lamprey and chickens. These new analyses will aid
in the understanding of the forces contributing
to the construction of normal human ocular
lenses. Ultimately, it should also give us
insight into congenital eye abnormalities such as
Cyclopia and Micropthalmia.
We are interested in these reconstructions
because they make excellent model systems at the
Tissue, Molecular, and Cellular level. Our
interest is in the geometrical transformation the
tissue goes through in the course of
production. Flat plates are seen during early
development, by stage 12 they get larger. We
suspect the major driving force is the growth and
division of cells. During the placode stage (13)
there is an increase of cells, that leads to a
cup formation in stages (14, 15). A deep cup
forms in stage 16 called the lens pit. In stage
17 the ectoderm pinches off to form the hollow
lens vesicle. These stages are not unlike what
we see in the development of the chick and mouse
lens. However they differ in size of the tissue,
cellular size, and developmental time. We are
asking whether the succession of geometries seen
at different stages represents a conserved
mechanism in development. That is to say, how do
the driving forces establish the structures in
the early lens, that are similar across the
vertebrate lineage? To establish this we took
advantage of digitized serial sections provided
by the Carnegie Foundation
Stage 13
Materials Methods
Stage 17

• We began by obtaining digital photographs of
  sections of the specimen from the Carnegie
  Collection.
• In stage 13 of the developing human embryonic
  lens there were 18 sections dedicated to our
  targeted region, each of which is 15 microns
  thick.
• A 3D modeling program called WinSURF will be
  used to model our lenses.
• In order to obtain accurate data from the
  software we had to first create a relative scale
  with our images by using a magnification grid
  provided with the digital sections.
• After the scaling was set. We then manually
  traced the regions of interest.
• This procedure was repeated throughout each
  section.
• The software then takes the tracing of the
  image, and stacks them in its respective order
  to create a 3D model.
• We can then obtain volumetrics from the
  software, which provides us with perimeter
  length, surface area, and volume measurements.
• Using the data we can then derive addition
  geometric properties of our model such as Tissue
  Height, Basel Area, and Apex Area.
• Using the derived data with reference data (Cell
  Volume), we can find the Cell number for each
  lens.

Introduction
Our human embryological specimens of study were
originally gathered by the Carnegie Foundation
and have since become property of the National
Museum of Health and Medicine, and the Walter
Reed Army Medical Center in Washington,
DC. Human Embryos were placed in a fixative over
100 years ago. At a later time the fixed embryos
were processed in an alcohol and xylene series.
Finally, they were embedded in paraffin and
serial sectioned in their entirely at 10-30
microns on a paraffin microtome. Digital serial
photographs were produced from the sections, and
samples were obtained from the National Museum of
Health and Medicine. Data was extracted from
targeted internal structures (like the lens) of a
human embryonic fetus for the study of the
formation of the visual system - in particular
the development of the embryonic lens at various
fetal stages. Studying the shape and location of
these structures and how they are connected to
each other is essential for understanding human
development. It is also the basis for knowing
how and when errors in development occur and if a
possibility exists for a corrective intervention.
Data
Cell Cycle
Bibliography
Dolye, M., Ang, C., Raju, R. Willisams, B.,
DeFanti, T., Goshtasby, A., Grzesczuk, R., Noe,
A. 1993 Processing of Cross-Sectional Image Data
for Reconstruction of Human Developmental Anatomy
from Museum Specimens. ACM SIG BIO Newsletter,
139-14. Bozanic, D., Saraga-Babie, M. 2004
Cell proliferation during the early stages of
human eye development. ANAT. EMBRYOL
208381-388. Cohen, J. 2002 Embryo Development
At the Click of a Mouse. SCIENCE, 297 1629
Zwann, J., Hendrix, R. 1973 Changes in Cell
and Organ Shape during Early Development of the
Ocular Lens. AMERICAN ZOOL. 131039-1049.