Figure 1R. Gasser, Ph.D. Department of Anatomy, Louisiana State University Medical Center, New Orleans, Louisiana.
Three ongoing projects will be presented and possible future projects will be discussed that are extensions of the ongoing ones. The first project (with S. Shigihara) uses three dimensional (3-D) computer reconstruction technology and serially sectioned human embryos to determine and correlate the growth movements of various head structures. When magnification, view and central reference point are identical for a series of reconstructions at representative stages, each reconstruction then can be equated to one frame of a motion picture film. Growth movements (i.e., changes in size, shape and position) of ear structures and the brain/face have been correlated at stages 13-21 (5-21mm, 28-52 days). It is now possible to determine the 3-D movements of multiple structures that not only establish normal definitive arrangements but also birth defects.
The study of living human embryos in utero is now practical with ultrasound technology. The second project (with R. Dickey) uses transvaginal ultrasound and assisted reproduction technologies to determine the growth rate of living embryos and the chorionic sac in utero. Differences in crown-rump length over time of normal embryos and the chorionic sac diameter were determined in singleton pregnancies whose postinsemination age was known precisely as a result of in-vitro fertilization (n=28) or gamete intrafallopian transfer (n=79). The growth rates of normal embryos will be presented as well as those with abnormal karyotypes. Comparisons will be made with data previously used on fixed specimens. Future studies (Dickey et al.) will determine uterine artery blood flow rates using duplex dopler ultrasound. These data will be correlated with the embryonic growth rate to determine the effect of uterine blood flow on growth rate and pregnancy outcome.
The third project (with R. Whitworth) produces interactive, instructional programs containing high resolution (2048 x 2048 pixels), digital images of the serial sections in registry of collected human embryos. After the external surface, central nervous system and notochord are reconstructed in 3-D the embryo models and the digitally captured sections are combined so that the viewer can image the sectional morphology at any level in the embryo. The sectional morphology and model of an embryo at the end of the first month of gestation (stage 13, 5mm) will be presented. Pointing the mouse controlled stilus to levels of the model and activating the button illustrates the section at each level. Insets at the bottom of the monitor show the plane of the section in the model. Names of the structures in the section are given automatically when touched with the stilus. The technology permits the preservation and storage of the serial sections of collected embryos as high resolution digital images. Embryo sections can be made available in registry to any investigator or instructor. It is also possible to produce accurate models that illustrate the 3-D morphology of the human embryo with each of its systems at every stage of development. It is now feasible to study the relationships of multiple systems in 3-D as the normal definitive arrangement or a birth defect is established.
Figure 2
Figure 3