Transcript 3D computerized reconstruction of the human embryonic lens

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 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.
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.
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
Materials & Methods
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
Stage
Time
(days)
Tissue Height
(μm)
Tissue
Thickness
(μm)
13
32
35.79
10
46040.45
46040.45
920808.90
921
17
45
42.81
15
63641.78
45775.49 1569686.17
1570
Section
Stage 17 Perimete Perimete Area
Section r Base
r Apex
Base
1083
1084
1085
1086
1087
1088
1089
1090
352.328
563.771
661.151
723.998
709.644
643.905
433.57
154.418
228.442
433.362
580.965
644.75
649.382
514.798
-
7910.43
17802.70
24323.60
28076.60
29796.50
28287.30
13930.10
1748.38
Section
Area
Apex
Surface
Area
Tissue
Height
2636.81
8622.31
14146.5
14385.7
17694.5
15427.9
-
5273.62
9180.39
10177.10
13690.90
12102.00
12859.40
13930.10
1748.38
41.58192
48.08064
38.38262
48.00982
40.40596
40.40596
Basal Area Apical Area
(μm2)
(μm2)
Tissue
Volume
(μm3)
Cell Number
(Vt/C#)
Tissue
Thicknes
s
Section
Volume
(A*t)
Pb*Tt
Surface
Base
Surface
Apex
Cell
Volume
19.19131
24.00491
19.19131
24.00491
20.20298
24.20329
10
10
101207.68
220374.44
195311.88
328648.82
244496.46
311239.79
139301.00
17483.80
6761.64
13533.27
12688.35
17379.51
14336.92
15584.62
4335.70
1544.18
4384.101
10402.82
11149.48
15477.17
13119.45
12459.81
-
1000
1000
1000
1000
1000
1000
1000
1000
Cell
Tissue Number
Volume (Vt/C#)
*****
321582.1
516894
845542.8
1090039
1401279
1540580
1558064
*****
321.5821
516.894
845.5428
1090.039
1401.279
1540.58
1558.064
G
t  to
Vt
3.3223log10 ( )
Vo
• 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 it’s 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.
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, 13:9-14.
Bozanic, D., Saraga-Babie, M. 2004 “Cell proliferation during the early
stages of human eye development.” ANAT. EMBRYOL 208:381-388.
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. 13:1039-1049.
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