BR 4D movie

3-D concept (Focal Planes)

Imagine this as an egg. Because it is 3 dimensional, it is difficult to penetrate and see its inside. Each white line represents a section (called a focal plane) through this egg. Focal planes aid in the observation of biology events inside the egg.	This is a 3D image. This set of images is from one "time point". Thus, it is 3D instead of 4D. This C. elegans embryo image was generated using a computer program (VisBio). Each section represents a focal plane. Observe a movie that might give you a better idea of a 3D embryo.

3D + Time Series
With the 3D concept in mind

Time: 00:00:07 The beginning of the embryonic development. This is an one-cell embryo with maternal and paternal pro-nuclei at opposite ends of the embryo.	Time: 00:16:50 After about 16 minutes, this embryo develops into a two-cell embryo.

4D Movie Demo

Below is a 4D movie that was composed by 3 focal planes – focal plane 2, 4 and 6 (for demonstration purpose we only picked these 3 focal planes to use.). Try to go up, down, forward and backward to see how biological events change in space (focal planes) and time. For instance, you might see nuclei in focal plane 6 but not in focal plane 2 and 4.

Click on the center button to play this movie.

(7.6 MB)

Optical Sectioning Microscopy: Various Focal Planes of a 4D Data Set
(mouse-over the titles)

This image is an expansion of a 4D movie like the one you saw in "4D Demo". It is a 4-dimensional data set consisting of images taken at predefined intervals and optical sections. Researchers can specify the number of optical sections they wish to observe for a given time point and then the microsope system changes focus to obtain each focal plane. Such optical sectioning not only allows researchers to observe events that might be happening at different planes of focus but also allows them to create a data set that has the biological events they are studying in the best focus. For example, here, the researcher used 4 focal planes with 5 time intervals for every focal plane. The images you see here are all from a single embryo. Accordingly, each row, from left to right, is the same embryo at a different time point. Each column, from top to down, is the same embryo in different focal plane. When the recording was done, the researcher can select the focal plane that contains the most relevant data. Here, for example, from top to bottom, the 3rd image might be the best choice.

Image Credits:

1. The "Various Focal Planes of a 4D Data Set" (DeVries, J.H., Thomas, C., White, J. (1996). Four-Dimensional Imaging: Computer Visualization of 3D Movements in Living Specimens. Science, 273, 603-607.)