Sliding blade microtome

The sliding blade microtome is a tissue specimen cutting device including a specimen syringe and an adjustable cutting mechanism for diagonally slicing the specimen. The specimen syringe is a cylindrical shaft having a first end and a second end for holding and supporting a specimen. The first end has a diameter that is smaller than the diameter of the shaft, forming a compressed lip for applying pressure on the specimen prior to slicing by the blade. The pressure used to compress the gelatin and the specimen holds the gelatin and the specimen in a sturdy position to slice the specimen to precision without chatter marks. The specimen is pushed out of the first end of the specimen syringe by a motor mechanism or a manually adjustable micrometer drive.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to microtomes, more specifically to a sliding blade microtome.

2. Description of the Related Art

Much modern scientific research involves microscopic analysis. Much of today's microscopic analysis requires tissues to be prepared by devices that provide thin specimens, such as microtomes. Many microtomes are specifically designed for preparing specimen for certain types of microscopes. For instance, rotary microtomes cut thin sections of specimen for light microscopy and ultramicrotomes are used to prepare ultrathin sections for light and electron microscopy. Live tissues, such as brain or liver tissues, are prepared by oscillating or vibrating blade microtomes called vibratomes. Vibratomes are currently employed in biomedical studies such as electrophysiology recording, organotypic tissue culture and immunohistochemistry experiments. Though vibratomes have advanced the study of live and fresh tissues, there are disadvantages, such as slow cutting speeds, inconsistent slice thickness, lack of a support for the specimen and the presence of chatter marks on the sliced specimen, that leave the vibratome lacking as a fully efficient microtome. A microtome is desired that will uniformly slice specimen at a specific thickness without imparting chatter marks on the slices. The microtome should not only securely hold, but also steadily support the specimen. Thus, a microtome solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The microtome is a tissue specimen-cutting device for producing high quality specimen slices. The device includes a bath, a specimen syringe for holding, supporting and compressing the specimen, and an adjustable cutting mechanism for diagonally slicing the specimen. The cutting mechanism has a linear way guide, a mounting accessory slidingly attached to the linear way guide, and a cross clamp attached to the mounting accessory, a blade holder being adjustably attached to the cross clamp and holding a blade.

The specimen syringe is a cylindrical shaft having a first end and a second end for holding and supporting a specimen. The shaft and the second end have the same diameter. The first end has a diameter that is smaller than the diameter of the shaft and the second end, forming a compressed lip at the first end. A specimen is prepared by gluing it to a first end of a plunger and embedding the specimen in a gelatin, such as low gel point agarose or similar material. The specimen is pushed out of the first end of the specimen syringe by placing pressure on a second end of the plunger using a motor mechanism or a manually adjustable micrometer drive.

Thus, as the specimen is pushed out of the compressed lip at the first end of the specimen syringe, pressure is applied to the specimen and the gelatin. This pressure functions to compress the gelatin and the specimen when they are forced out of the opening of the specimen syringe, thereby clamping and holding the gelatin and the specimen in a sturdy position to slice the specimen to precision without chatter marks.

The blade of the cutting assembly is disposed adjacent the first end of the specimen syringe. A cutting plane is defined along the first end of the specimen syringe. The blade can be angled by rotating the blade holder about the cross clamp to define a cutting angle against the cutting plane.

Ideally the first end and a portion of the syringe shaft are disposed in a bath through a syringe aperture. The syringe aperture is completely submerged under a buffer medium, which is held in the bath. A sealant ring seals the gap between the specimen syringe and the syringe aperture of the bath, thereby preventing the buffer medium from leaking.

A spacer ring surrounds the specimen syringe and works together with a stopper, which is disposed on the syringe, to determine how much of the syringe will be exposed in the bath. The syringe slides into the bath until the stopper abuts the spacer ring and impedes the syringe from moving. The width of the spacer ring, therefore, directly determines how much of the syringe is exposed. A wide spacer ring allows only a small portion of the syringe to extend into the bath, and a narrow spacer ring allows a larger portion of the syringe to extend into the bath. The specimen, as well as the tissue slices cut by the microtome, is disposed in the bath, where the buffer medium not only provides oxygen and nutrition to the specimen, but also lubricates the blade as it cuts the specimen in the bath.

These and other features of the present invention will become readily apparent upon consideration of the following specification and drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a sliding blade microtome, a first embodiment of which is designated as100in the figures. The sliding blade microtome100is a tissue specimen-cutting device for slicing live and pre-fixed tissue. The microtome100has a base115for supporting a specimen syringe130having a first end132and a second end134, a bath120having a syringe aperture122, an adjustable cutting mechanism150and a micrometer drive172. The first end132of the specimen syringe130is ideally disposed through the syringe aperture122of the bath120. The second end134of the syringe130is disposed adjacent the micrometer drive172.

Referring toFIGS. 1–3, the cutting mechanism150is shown comprising a mounting accessory156having an axis rod160, a cross clamp158, a blade holder162and a blade168. The cross clamp158is disposed on the axis rod160of the mounting accessory156. The cross clamp158serves as a support to which the blade holder162is pivotally attached. The blade168is clamped to the blade holder162by a blade clamping plate166and is tightened in position using screws164.

The cutting mechanism150is disposed on a linear way guide154that is mounted on a support arm152of the base115. The mounting accessory156is the portion of the cutting mechanism150that directly contacts the guide154. Specifically, the mounting accessory156allows the cutting mechanism150to slide from a first end153of the linear way guide154to a second end155. The second end155of the linear way guide154is disposed adjacent the first end132of the specimen syringe130that is situated within the bath120. The linear way guide154may be tilted up or down to dispose the guide154at any angle above the bath120. The linear way guide154is pivoted about a bolt that is secured through one of a number of holes in the support arm152. The first end153of the guide154may be level with the second end155, or may be raised above the second end155.

Referring now toFIG. 3, the specimen syringe130is a cylindrical, hollow shaft designed for supporting and holding a specimen148. The specimen syringe130is positioned and clamped in place on an immovable syringe mount126on the base115. The first end132of the syringe130has a diameter that is smaller than the diameter of the second end134and the body of the syringe130, and consequentially defines a compressed lip. The compressed lip at the first end132has a smaller cross section than the rest of the syringe130.

The specimen syringe130holds the specimen148after it is prepared on a plunger140. The specimen148is prepared by being fixed to a first end142of the plunger140with an adhesive, such as isocyanate glue or the like. Afterwards, the specimen148is embedded in a gelatin146, such as a low gel point agarose, molten agarose or similar material once the specimen148is affixed to the plunger140in the syringe130.

The compressed lip at the first end132of the syringe130is the mechanism through which pressure is placed on the gelatin146and the specimen148as they exit the syringe130. The pressure applied by the compressed lip restricts movement of the specimen148and the gelatin146, holds both the gelatin146and the specimen148in a firm, sturdy position, and mechanically solidifies the two into a firmer mass. The importance of applying pressure to the gelatin146and the specimen148prior to being cut is to counteract mechanical stresses of the blade168as it cuts the specimen148. Mechanical stress can cause tissue distortion and cell damage of the specimen148during slicing. Thus, due to the pressure from the compressed lip of the first end132, the specimen148can be precisely sliced without chatter marks.

Once the gelatin146and the specimen148are pushed past the compressed lip of the first end132of the syringe130, the operator can slide the blade168from the first end153to the second end155of the linear way guide154to cut the specimen148. The angle of the linear way guide154over the first end132of the syringe130determines how the specimen148is cut. If the guide154is angled so that the first end153is disposed higher than the second end155, then the blade168cuts the specimen148diagonally, since the angle of the guide154relative to the support152is locked while sliding the cutting mechanism150along the guide154.

The blade168slides along the guide154, abutting the first end132of the syringe130. Specifically, the blade168, via the blade holder162, is rotated at an angle from a cutting plane170, which is the outermost end of the first end132. The blade168forms an acute angel with the cutting plane170. The cutting plane170is perpendicular with the axially oriented syringe130. The cutting angle may be adjusted by rotating the blade holder162in the cross clamp158to increase or decrease the angle between the blade168and the cutting plane170. Once the blade168cuts slices from the specimen148, they fall into the bath120.

As described above, the first end132and a portion of the shaft of the syringe130are disposed through the syringe aperture122of the bath120. The bath120has a bottom wall and at least one peripheral wall extending around the bottom wall; the bath holds a buffer medium121such as saline. The syringe aperture122is completely submerged under the buffer medium121. To prevent the buffer medium121from leaking a sealant ring124seals the gap between the specimen syringe130and the wall of the bath120. The sealant ring124is disposed adjacent the syringe aperture122and is sandwiched between the bath120and the syringe mount126. The buffer medium121both lubricates the blade168as it cuts the specimen148and provides oxygen and nutrition to the specimen148and the specimen slices cut by the microtome100. In alternative embodiments, the bath120may be disposed below the syringe130to catch the specimen slices that are cut by the microtome100.

The portion of the syringe130that is disposed through the syringe aperture122is determined by a stopper129that is welded or otherwise disposed on the outside of the syringe130, and by a spacer ring128. The spacer ring128surrounds the specimen syringe130and is sandwiched between the syringe mount126and the stopper129. The syringe130moves axially through the syringe aperture122until the stopper129abuts the spacer ring128and stops the syringe130. The width of the spacer ring128is a significant factor in determining how much of the syringe130is exposed in the bath120. For instance, a wide spacer ring128allows only a small portion of the syringe130to extend into the bath120. Narrow spacer rings128allow a larger portion of the syringe130to extend into the bath120.

The thickness of the slices cut from the specimen148may be controlled by the axial movement of the plunger140through the specimen syringe130. The axial movement of the plunger140through the specimen syringe130may be controlled manually or mechanically. As shown inFIGS. 1–3, the specimen148may be pushed out of the first end132of the specimen syringe130using a micrometer drive172. A micrometer tip176of the micrometer drive172is positioned at a second end144of the plunger140and incrementally pushes the specimen148out of the first end132of the syringe130. The micrometer drive172is mounted on a micrometer mounting block174of the base115.

FIG. 4shows a second embodiment of the microtome, which is an automated microtome200that drives the plunger236through the syringe130via a control unit220, sensors240,250, motors242,252, lead screw blocks244,254and lead screw246,256. The motor242drives cutting mechanism232through lead screw246and lead screw block244. The motor252operates the plunger236, moving it forward using lead screw256and lead screw block254. The control unit220monitors the positions of the lead screw blocks244,254through sensors240,250, respectively, and sends commands to control the motors242,252, respectively.

The microtomes100,200differ in how the plungers140and236, respectively, are pushed out of the syringe130. However, both microtomes100,200hold and support the specimen148using the specimen syringe130. Also, both have the compressed lip at the first end132to compress the specimen148prior to being sliced by the blade168. Furthermore, the cutting mechanism150,232of each microtome100,200is directed to slidingly cut specimen148directly within the bath120as the blade168slides from the first end153to the second end155of the linear way guide154.