"PLASTINATION" - by Indigenous Method

(A New Art in Science)

INTRODUCTION:

One of the new areas for synthetic materials is the preservation technic PLASTINATION. The routine formalin preserved wet organs, dissection specimens, have their own drawbacks. Handling the formalin preserved specimens has an important disadvantage of irritating odor, bleached colorless parts, not giving a naturalistic idea. The sections are difficult to maintain. The luminal architecture, dimensions & branching patterns are almost impossible to imagine in a dissection. Plastination is a technic of preparation of dry, colored, non-toxic, durable, odorless, natural looking specimens. The different methods of Plastination have promising solutions for most of the problems. The objective of learning Medicine is to help understand the normal human body and changes during the disease process. The size, shape, consistency, & relationships in a 3-dimentional orientation of different biological specimens should to be understood. Keeping the above points in mind, newer areas have been explored to eliminate the drawbacks.

There are many processes by which the plastination of a specimen can be done. The method explained below is the Economical and Easy Process by which Plastination can be done in your labs and museums.

View the articles by Dr. N. M. Shama Sundar.(Hosted on Blogger/Blogspot)

METHODS:

There are 3 methods of Plastination -
  1. Whole organ Plastination:
  2. Sheet Plastination
  3. Luminal cast Plastination

Whole Organ Plastination

By this technic, any part can be Plastinated for the purposes of understanding the total structure and relationships. Compared to the preserved specimens, fresh ones give excellent results.

The specimens are washed with tap water to remove the dirt, blood, contents etc. Irrigation with mild detergent solution and washing with the dilute hydrogen peroxide cleans mucus, pus, blood in the blood vessels. After this immerse in 5 times the volume of 10% Formalin or color retaining Special Plastination preservative containing -

95% Alcohol ………………………280 ml
Formalin ……………………………120 ml
Glycerin …………………………….80 ml
Phenol ………………………………120 ml
Dist. Water …………………………800 ml

48 to 72 Hrs are needed to complete fixation.

The Formalin is washed in running tap water for 12to 24 Hrs. Now the specimen is transferred to jars containing (at least 10 times vol) of Acetone, at intervals of a new days to a few weeks, depending upon the size of specimen. Acetone also removes the fat, completion of dehydration is assessed by measuring the S.G. of Acetone which should remain at 0.89. Transfer the specimen to fresh Acetone, if it does not turn yellow, it indicates total removal of fat. Now it is transferred to a jar of Resin & left in it for 1 to 2 weeks. Finally the specimen is immersed in a mixture of Resin, (POLYPROPYLENE RESIN) Catalyst (5%) & accelerator (0.1%). The Specimen after a few hours becomes non-sticky. The specimen is mounted on a suitable base & properly oriented. Coloring can be done at any stage, to highlight specific parts or areas. The beautiful, colored, dry, odorless, non-toxic, durable, inexpensive, maintenance free, natural-looking, real specimens. Outbeat the routine specimens.

Sheet Plastination:

This is a wonderful method, of preparation of thin-transparent or thick-opaque body sections. The sheets are totally portable, the whole body being convertible into slices & stored dry. The inter-relationships are best appreciated by this technic & comparison with C.T. Scans & M.R.I.s is possible.

Fresh parts (note that preservation is not at all necessary & colors are wonderfully maintained) are deep frozen for 24 hrs & thin- 3mm sections taken with a band saw or preserved frozen parts are sectioned at 1cm slices. Further processing is similar to the classical Plastination technic up to the stage of resin impregnation.

THIN TRANSPARENT SECTIONS:

The section has to be cast in the form of a sheet. This requires a double-glass chamber - Appropriate sized 3-4 mm (window pane) glass sheets re selected, sharp edges need to be ground to prevent injury during handling; cleaned and a sheet of same sized OHP transparency is kept on the glass sheet; a rubber tube (petrol pipe) with a stiff metal wire inside (to give a shape) is placed on the OHP sheet clad glass sheet; another glass sheet with OHP sheet covering is the next layer; now clips are put to the bottom and sides at intervals of 3 to 4 inches; this gets a glass chamber.

The two glass sheets- 4mm thick are separated by a rubber tubing of 6-8 mm diameter; clips hold the glass sheets together & make a leak proof chamber. The processed section is placed in the middle of the chamber, Resin, Catalyst (5%) & accelerator (0.01%) mixture is filled into the chamber slowly. After 12 hrs, clips are removed; glass sheets are carefully separated from the resin sheet; edges are trimmed, polished & the specimen is labeled.

Now the thin slice of processed organ (dehydrated, defatted & resin impregnated) is carefully placed in the center of the glass chamber; a thin transparent nylon wire is useful in properly orienting the specimen; a mixture of resin, catalyst & accelerator is carefully poured into the chamber, using a plastic (a used OHP sheet rolled & stapled) funnel; this is kept in the vertical position for a day.

Next day, the clips are removed one by one symmetrically, the glass sheets usually come apart or need a little separation if resin was sticking them; the transparency sheets are carefully peeled off from one edge; the tubing has to be similarly6 separated from one end; it is worth to withhold one's curiosity if there is any doubt that it is till not totally solidified, another day of patient waiting is preferred, than losing a precious specimen; drying in heat, sunlight is not recommended. Edges can be finished using a grinding machine; labeled & stored in plastic covers or dust proof boxes.

THICK SECTIONS

After resin impregnation, the section is immersed in a mixture of resin, catalyst & accelerator for a few hours dried & stored in a clean cover.

EXCELLENT HERBARIUMS?

Preservation of plant twigs in the Herbariums, has been the routine method, with its disadvantages of color change, shrinkage, fungal & pest infestation, and detachment of parts from the main stem. We have many a times wondered whether any alternative method, overcoming these problems can be thought off.

SHEET PLASTINATION appears to be the right answer.

Carefully selected twig {remember - a permanent, not so expensive procedure, taking your precious time, needs a good specimen} of appropriate size, is cleaned of the dust, broken leaves etc and immersed for about 5 seconds in a cup of warm water (<500 C) to which a pinch of MgO has been added. This prevents Chlorophyll degradation & retains the green color.

Now the twig is carefully pressed between 2 sheets of blotting paper to remove the water on the surface. It is immersed in wide mouthed bottle containing Acetone- a dehydrating agent.

Meanwhile, a glass chamber is prepared by placing a Plastic pipe (diameter decided by the thickness of the twig ) between 2 [window] glass sheets (size depending on the overall size of the material ) and putting clips on the sides & bottom as shown in the diagram. Clean O.H.P transparency sheets on the inside of the glass sheets has been found to be useful in preventing the Plastinated specimen from sticking to the glass.

The twig is now carefully placed in the glass chamber & positioned properly using a blunt wire. A mixture of Resin, catalyst & accelerator in the proportion of 100:5:0.1 is slowly poured into the chamber using a folded plastic funnel, till the twig is completely immersed. Repositioning the parts of the twig may be necessary.

Next day, confirming the resin has set, (touching the surface with a needle ) slowly remove the clips one by one. Separate glass sheets from the O.H.P. sheets. Carefully pull apart the OHP sheets & tubing. Leave it dry for a few hours if necessary. Trim the edges using grinding stone. Attach the lable in a corner. Stack them in dust proof boxes. Plastinated herbarium is ready.

Luminal Cast Plastination

This technic is useful to study the dimensions & architecture of different cavities of organs and to study the tubular - arterial, venous, ductal branches & their variations. The principle involves filling up of the lumen with material and dissolving the surrounding tissue. This is used for tracheo-bronchial cast of lungs, cerebral ventricles; bony labyrinth; vascular patterns of kidney, liver, lung, spleen, coronary vessels etc.

Fresh organ is preferred, because alterations during preservation give a wrong picture of the interior. The lumen is cleaned using warm tap water; heparinised solution; hydrogen peroxide or deaerated water containing dish water detergent. The mucus, blood, secretions, etc will be cleared. It pays to clean repeatedly with lots of patience till the fluid coming out is as clean as the ingoing one.

Approximate volume of the casting material necessary can be calculated by observing the amount of washing fluids used. After clearing the excessive amount of water in the lumen by blowing air and tilting the organ & draining by gravity, using appropriate sized plastic tubings & syringes, the Plastination materials _ (Resins - are brittle preferably Rubber Silicone _ available as ready packed gel - (used as sealant in engg. field)) is injected gently. Blocking or tying of entry port may be needed to prevent escape of material.

24 hrs later, some dissection of larger easily removable structures, and boiling for half to one hour dissolves most of the tissues, leaving the beautiful luminal cast materials. Some finishing touches may be necessary.

Colors can be added at any stage to highlight different areas. The cast is displayed in a suitable manner. The Rubber Silicone produces an excellent, soft, flexible cast, showing a n unimaginable 3 - dimensional orientation of the cavity, including the abnormal extensions if any. Chloroform may be used to dilute the silicone for very fine lumina. (Shrinkage is expected due to dilution)

SUMMARY

Each of the above methods Plastination produces an unique specimen at a very low cost, almost equivalent to the Plastinated specimens of international quality. The protocol is so simple, that one can very easily start a Plastination lab in the dept. These are best suited for teaching purposes; discussions, training of diagnostic & therapeutic procedures; designing of newer surgical procedures; practice skills; research etc. There is a lot of scope for this technic in different biological fields & different branches of scientific field.

Materials needed:

  1. Jars for storage & processing;
  2. Color preserving fixative;
  3. Absolute alcohol;
  4. Acetone;
  5. Silicone Rubber;
  6. PP Resins, Catalyst, Accelerator;
  7. Chloroform;
  8. Fluorescent Color paints;
  9. Dissection instruments;
  10. Syringes, needles
  11. Glass sheets 4mm 6"x6"
  12. Petrol pipe
  13. Stiff wire
  14. OHP sheets
  15. Clips

Whole organ Plastination:

Sheet Plastination (Herbarium):

Luminal cast Plastination


For further details please contact the author -

Dr. N. M. SHAMA SUNDAR Dr. N.M. SHAMA SUNDAR

Professor & Head,
Department of Anatomy
JSS Medical College,
Mysore - 570015

Tel: 0821-2548339 (Office)
Mobile: 9845206284, 9900568339
Fax: 0821-2493819

e-mail: shamdr_in (at) yahoo.co.in


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