MICROTOMY METHOD AND DEVICE

Abstract

A microtomy method, blade holder and microtomy apparatus is described in which the microtomy blade or sample block is agitated ultrasonically. The sample block and/or cutting blade may be ultrasonically agitated and the invention provides a device for use in microtomy comprising a blade holder adapted to be agitated ultrasonically and to receive a sample sectioning blade and an ultrasonic source arranged to in use to cause the blade to vibrate in one or more directions within the plane of the blade.

Claims

1. A method of preparing a section of a sample comprising providing a sample for sectioning in a sample block, providing a cutting blade in a sample section device wherein the cutting blade is adapted to move to provide a slicing locus and the blade and/or sample block is subjected to ultrasound whereby the blade and/or sample block vibrates and effecting relative movement between the sample block and the cutting blade such that the cutting locus of the blade intersects the sample in the sample block causing slicing engagement between the blade and the sample in the sample block thereby to produce a sliced section of the sample.

2. A microtomy apparatus comprising a sample block holder, a base for carrying the sample block holder, the base being adapted to receive a blade holder for carrying a cutting blade, means to effect relative movement between the sample block holder and the blade such that the cutting locus of the blade intersects the sample in the sample block causing slicing engagement between the blade and the sample and wherein the microtomy apparatus and/or blade holder comprises an ultrasonic source arranged to, in use, cause the sample block and/or the cutting blade to vibrate.

3. A microtomy apparatus according to claim 2 wherein the ultrasonic source is arranged to ultrasonically agitate the blade holder such that it vibrates in one or more directions within the plane of the blade.

4. A microtomy apparatus according to claim 2 wherein the ultrasonic source is arranged to ultrasonically agitate the sample block.

5. A device for use in microtomy comprising a blade holder adapted to be agitated ultrasonically and to receive a sample sectioning blade and an ultrasonic source arranged to in use to cause the blade to vibrate in one or more directions within the plane of the blade.

6. A sample sectioning device for use in microtomy comprising a blade holder adapted to be agitated ultrasonically, a replaceable sample sectioning blade having a cutting edge and mounted in the blade holder and an ultrasonic source arranged to cause the blade to vibrate in the direction of the cutting edge or at right angles thereto within the plane of the blade.

7. A sample sectioning device according to claim 6 in which the blade is planar.

8. A sample sectioning device according to claim 6 having an “x” direction parallel to the cutting edge and a “y” direction perpendicular to the cutting edge of the blade wherein the blade is arranged to vibrate in the “x” direction, the “y” direction or both the “x” and the “y” direction.

9. A sample sectioning device according to claim 8 in which there is no substantial vibration in the “z” direction,

10. A sample sectioning device according to claim 6 wherein the ultrasonic source is a transducer.

11. A sample sectioning device according to claim 10 wherein the transducer is located at the opposite side of the blade holder to the blade.

12. A sample sectioning device according to claim 6 wherein the blade is made of steel.

13. A sample sectioning device according to claim 6 wherein the ultrasonic source is arranged to cause the blade to vibrate at a frequency of at least 10000 Hz.

14. A sample sectioning device according to claim 6 adapted to provide a section of a sample having a thickness of greater than 1 micron to 1 mm.

15. A microtomy apparatus comprising a specimen holder, a base for carrying the specimen holder, a sample sectioning device according to claim 6, the base being adapted to receive the sample sectioning device and means to effect relative movement between the specimen holder and the sample sectioning device.

16. A retrofittable device adapted to be carried by a microtomy apparatus comprising a device according to claim 6, the device including means for securing the device to the microtomy apparatus.

Description

[0038] The present invention is further described by way of example only with reference to the accompanying drawings, in which;

[0039] FIG. 1 shows a perspective view of a sample section device comprising a blade holder and blade according to the invention;

[0040] FIG. 2 shows side elevation of a blade position relative to a sample black in which it is positioned to test the penetration force of the blade;

[0041] FIG. 3 shows a schematic arrangement for determining penetrative force;

[0042] FIG. 4 shows a perspective view of an alternative sample section device comprising a blade holder and blade according to the invention;

[0043] FIG. 5 shows side elevation a sample section device according to the invention positioned to slice a section from a wax block and sample embedded in a histology cassette;

[0044] FIGS. 6 and 7 show a plot of penetrative cutting force for several samples cut in accordance with a method and device of the present invention (right hand columns of each pair of columns) and samples cut in a conventional cutting arrangement (left hand columns of each pair of columns); and

[0045] FIG. 8 shows a graph of variation in cutting force with time for a method and device according to the invention as compared to a conventional method and device.

[0046] In FIG. 1, the blade 1 has a blade edge 2 and two opposed sides 3, 4. In use the blade 1 is positioned relative to a sample block 5 and the angle A between the blade face 3 and the sample block 5 is referred to as the blade clearance angle. The angle between the two opposed sides 3, 4 of the blade 1 is known as the facet angle. During use, the blade and/or sample are moved into a position where the cutting edge of the blade intersects the sample and the blade is moved so as to cut a section 5a of the sample whereupon the section is separated from the sample block and rests on the side of the blade or blade holder, the blade is retracted from the sample with the section and the section is then subjected to downstream processing as appropriate.

[0047] FIG. 2 shows a sample section device according to the invention comprising a blade 1 and a blade holder 6 and an ultrasonic source housed within block 7 of the blade holder 6. FIG. 2 shows a point 8 at a central point on the blade edge at which measurement of the vibration (amplitude) of the blade edge is carried out. This is also denoted MP1 signifying “measurement point 1”. The blade holder is connectable to the base of a microtome at lugs 9a and 9b. The blade holder suitably has a node point as measured at location MP2 on lugs 9a and 9b and measurement of vibration at this point may be carried out to ascertain the appropriate frequency to apply to secure minimal vibrational amplitude whereby there is minimal and preferably no movement. This location is denoted MP2 “measurement point 2” and is used as a reference point at which wave amplitude is measured and from which modifications to the design of the blade holder may be made to reduce and preferably avoid vibration at this location. The blade 1 is secured to the blade holder 6 by releasable securing means 10, The releasable securing means suitably comprise complementary engaging parts formed on the blade 1 and the blade holder 6. As examples, the blade holder may be affixed to the microtome by clamping or engaged with complementary sliding parts.

[0048] FIG. 3 shows a sample sectioning device in a side elevation in an arrangement for testing penetrative force as set out in the Examples below. The block 5 is moved toward the blade 1 in direction D and the penetrative force required for the blade to penetrate into the body of the block (as opposed to cutting a section) was measured.

[0049] FIG. 4 shows a sample section device according to the invention comprising a blade 1 which may be secured to the blade holder 6 by fixing means 10. The blade holder 6 houses an ultrasonic source such as a transducer within the dome-shaped part 7 and is mounted on a mounting 11 through a trunnion arrangement. The transducer is connected to an electrical supply whereby electrical energy may be converted into mechanical energy. The mounting 11 comprises a base part 12 having engaging means 13a, 13b and 13c for engaging with a microtome to securely fix the mounting 11 to the microtome and further comprises arms 14a, 14b each provided with a recess to receive a lug 15 of the blade holder 6. The blade holder is rotatable about axis R whereby the angle of the blade 1 may be altered as desired. The lugs may be securely fastened in the recess to fix the position of the blade relative to the mounting. 11.

[0050] The dome shape 7 of the blade holder 6 provides another example of a blade holder and is intended to dissipate vibrations outwards to the edges of the dome so vibration is transmitted to the blade but in other directions, the vibration is minimised.

[0051] FIG. 5 shows a sample sectioning device in a side elevation in an arrangement for testing cutting force as set out in the Examples below. The block 5 is moved toward the blade 1 in direction D and the cutting force required to cut the block was measured.

[0052] The invention is illustrated by the following non-limiting examples.

EXAMPLE 1

[0053] A sample sectioning device according to the invention as shown in FIG. 2 was subjected to agitation in the x, y and z direction by applying voltages to the transducer as set out in Table 1 below. The transducer is located in a recess in the bottom of the blade holder. The transducer was tuned to a frequency of 40 to 44 kHz. The amplitude in each dimension was measured using a laser vibrometer at measuring point MP1 on the blade edge and at measuring point MP2 on the blade holder at the points at which the blade holder is attached to a microtome.

TABLE-US-00001 Vibration direction X Y Z Measuring Ampli- Ampli- Ampli- points Voltage tude Voltage tude Voltage tude (MP) (V) (μm) (V) (μm) (V) (μm) 1 0.8 3.04 Max 14 53.2 0.5 1.9 2 0.2 0.76

[0054] The measured amplitudes are shown in Table 1 demonstrating that there was minimal movement in the x and z directions at MP1 but significant vibration in the y direction. At MP2 there was minimal movement in the y direction. The blade holder would therefore experience minimal agitation at the location at which it is connected to the microtome.

EXAMPLE 2

[0055] A sample section device as shown in FIG. 2 was tested to determine penetrative force using an arrangement as shown in FIG. 3. Two samples were tested; a large paraffin sample block based on a large sample cassette of around 50 to 55 by 70 to 80 by 12 to 17 mm and available from Cellpath Ltd under the trade name SUPAMEGA having a depth of around two to three times that of a standard sized sample block based on a standard size histology cassette of 28 to 32 mm×25 to 28 mm×5 to 6 mm.

[0056] The force required to penetrate the sample by 4 mm for the larger sample and 2 mm for the standard sample was measured using a conventional cutting (CC) operation i.e. without ultrasonic agitation of the blade and a cutting operation using an ultrasonically agitated cutting (UAC) blade using a device as shown in FIG. 2.

[0057] The results are shown in FIG. 6 (larger sample) and FIG. 7 (standard sample). A reduction in penetrative cutting force is observed in all cases and a reduction of over 40% is observed for the standard samples.

EXAMPLE 3

[0058] A sample section device as shown in FIG. 2 was tested to determine cutting force required to produce a sample section of 1 mm thickness (without using any thickness control) using an arrangement as shown in FIG. 5. The blade was agitated using a transducer tuning frequency of 40 to 44 kHz.

[0059] The force required to cut the sample was measured using a conventional cutting (CC) operation i.e. without ultrasonic agitation of the blade and a cutting operation using an ultrasonically agitated cutting (UAC) blade using a device as shown in FIG. 2. The test was repeated using a different sample.

[0060] The results are shown in FIG. 8. A reduction in penetrative cutting force is observed in all cases and a significant reduction of at least 10% is observed for the standard samples.

TABLE-US-00002 TABLE 2 Maximum force (N) Sample CC UAC Force reduction (%) 1 39.3 20.8 47.1% 2 29.2 26.1 10.6%

[0061] The cutting force required over time was also measured and is shown in FIG. 8 for the two samples. The UAC run for the first sample required both a lower level of cutting force and a shorter duration for the cutting operation. The second sample also required a lower level of cutting force.

EXAMPLE 4

[0062] Samples of skin and prostate were sectioned using a sample section device as shown in FIG. 2 at a tuning frequency of 25 kHz, For comparative purposes, the same samples were then sectioned using the same apparatus but without using ultrasonics. The procedure of Example 3 was employed.

The procedure using ultrasonics resulted in less sample compression and a longer blade life than that without ultrasonics.