RE: [Histonet] different types of processors

From:Tony Henwood

I have used both types and agree with the comments made by Charles. Some further points:
1.    Closed systems process large blocks (eg brain) and fatty tissues better than open systems due to the stronger pressure and vacuum that can be applied.
2.    To obtain equivalent processing quality from an open system requires at least double the processing time.
3.    Because open systems are more gentle on tissues, small endoscopics and core biopsies process better than with closed systems.
4.    The choice? For large throughput, general path labs definitely consider at least one closed system processor and for Children's Hospital labs (smaller biopsies), open system processors are definitely wothwhile.

Tony Henwood JP, BAppSc, GradDipSysAnalys, CT(ASC)
Laboratory Manager
The Children's Hospital at  Westmead,
Locked Bag 4001, Westmead, 2145, AUSTRALIA.
Tel: 612 9845 3306
Fax: 612 9845 3318

-----Original Message-----
From: Charles W. Scouten, Ph.D. []
Sent: Friday, 21 November 2003 9:56 AM
Subject: RE: [Histonet] different types of processors


There are many real advantages to a dip and move system (OPEN)  when compared to a sealed flush (CLOSED) system. The following points highlight the operational differences 1) Time - the minimum cycle time for a flush system is 2 hours. This is due to the heating phase for the paraffin and the additional rinse cycles. For quick procedures such as biopsies, 2 hours is an inconvenient cycle time when it can be done in 30 minutes with a TPC system. A procedure that would take only 8 hours with the TPC will take 12 hours in a sealed system. 2) Artifacts – In order to introduce the paraffin in a sealed system, the chamber must be heated. This heating process can cause dead spots, shadows, or artifacts in your tissue. The TPC system does not create such artifacts. 3) Maintenance – The TPC system does not rely on pumps to complete the protocols. The sealed system requires pumps which can fail. These can be costly and inconvenient to replace. 4) Contamination – Although the sealed systems are thought to be contamination free, they do require cleaning after every protocol. Proteins are routinely washed out of sections during processing. These proteins will settle in the bottom of flush storage tanks and will be present for future protocols. In order to remove all contaminates, the system must be cleaned. 5) Cost – The TPC system uses a much lower volume of reagents and chemicals. These add up over the coarse of a year. Have you actually calculated your annual costs and looked at the potential savings? 6) Tissue Shrinking – The TPC system does not expose the tissue to a heating cycle and therefore does not cause the tissue to shrink.


I am also attaching a detailed data sheet here. If you have any questions or would like to discuss this further please feel free to contact me anytime.


Charles W.  Scouten, Ph.D.
5918 Evergreen Blvd.
St. Louis, MO 63134
Ph: 314 522 0300 
FAX  314 522 0377


-----Original Message-----
From: []
Thursday, November 20, 2003 3:10 PM
Subject: [Histonet] different types of processors


Would someone please explain the difference between an open processor and a closed processor....

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