Motion System Design

Linear gauge solves cranium counting conundrum

To most people, the brain is a mystery. To neuroscientists, it's an incredible system that provides answers to many of life's great secrets, like why humans and animals act and feel the way they do. Through biomedical research, scientists can identify subtle changes to the central nervous system by noting disturbances during development or as a result of disease. This information helps doctors provide better care for those with brain-based issues.

One new tool used for this purpose, stereology, became popular during the late 1990's. Stereology is a microscopy technique used to quantify properties of 3D objects from layered 2D sections. The technique makes it easier to analyze specimens — such as brain tissue — under a microscope, and improves the consistency of analytical results produced in the laboratory and reported in scientific publications. In fact, some scientific journals now require researchers to use stereological techniques for analyzing cell populations in order to be published.

Stereology is especially helpful when estimating cell populations in brain structures. MBF Bioscience, Williston, Vt., recently introduced its latest version of the Stereo Investigator 7, a design-based stereologic graphic imager that helps analyze the brain. The system includes a microscope, motorized stage with closed-loop focus control, high-resolution digital camera, and a PC workstation loaded with enhanced software — including an Optical Fractionator Workflow program that makes it easier to train people in stereology, an often tedious and complicated task.

“The new Optical Fractionator Workflow visualizes focal planes through thick slices of tissue and analyzes them in a systematic way,” says Paul Angstman, MBF Bioscience vice president. “It relies on a precise positioning system to optimize the motorized stage and focusing mechanism to create detailed and clear images.

“When you're doing stereology or neuron tracing, you need to be extremely precise,” says Angstman. “A key to all of our systems is the positioning of a microscope and the detection and implementation of focal changes. This is done by the motorized stages with help from an extremely reliable linear length gauge, which is accurate to ±0.05 µm.“

The linear length gauge ensures that the position of the system's microscope is exactly where it needs to be during brain tissue analysis. It is positioned on the microscope and works with the stage controller to facilitate precise movements while working in conjunction with the system's vertical-axis “Z” motor. The gauge effectively closes the loop, feeding information back and forth to the controller.

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