This type of preservation occurs by natural factors including freezing and dryness that may occur by dry-heat or dry-cold (Figure 1) and the soil nature [4] . The body or body parts preserved by this can be called the naturally mummified one.

It can be divided according to the causative agents which cause preservation of dead body. They are:

A) Natural mummification: This is caused by the Mother Nature which occurs when buried in [5] and climate conditions.

B) Artificial mummification or true mummification: This is the type of preservation that had been done by Ancient Egyptian civilization for religious concepts (Figure 2) [6] . According to Greek historian Herodotus there are three types of artificial mummifications and all of them share the same target of interception of decomposition of the dead body [7] .

Different materials had been used in the mummification include materials that desiccate and dehydrate such as natron salt and vegetable materials and those act as anti-bacterial factors such as Mastic, Lichen, Myrrh, Bitumen, Cassia, Onions, Beeswax, Lichen, Coniferous resin, Henna and Gum Arabic [5] .

Source: http://familypedia.wikia.com/wiki/%C3%96tzi_the Iceman

Source: http://news.softpedia.com/news/Scientists-Mummify-Human-Leg-in-Bizarre-and-Twisted-Experiment-482441.shtml#sgal_0

This is a method or technique used for the long term preservation of body or part of body [8] . This technique was established by German scientist Gunther von Hagens in 1977 [9] in laboratory of Heidelberg University [10] . The main advantage of this way of preservation that the specimens were dry, durable, odorless, handleable and storable manner [11] . In the process of plastination the fluids and lipids in biological tissues substitute by curable polymers commonly epoxy, silicone and polyester. As a result of this procedure the specimen gets harden and a natural look [9] and the decomposition which lead to putrefaction of biological tissues is intercepted.

As previously described many chemicals can be used to replace the fluid and fat this led to provide different techniques of plastination here we will mention some of this techniques.

a) Silicone plastination

Silicone plastination is one of most common techniques of plastination which can be used for body, organs, part of organ and slices [8] (Figure 3). The Plastination techniques depend on vacuum of original body or tissue fluid and replace it by special curable polymer of the standard silicone S-10 [9] . The fixative chemical mostly use is formaldehyde. This technique was invented by Gunther von Hagens [12] .

Silicone plastination consist of four steps after preparation of specimen and are dehydration, defatting, hardening and formaldehyde embalming or fixation (Figure 3, Figure 4).

b) Epoxy plastination

This techniques of plastination is usually used for tissue examination especially slices of 2 - 4 mm [13] . The techniques of preservation are similar to previous one and it substitutes of all water and most of lipid with curable resin [14] . The result of epoxy plastination is durable sectional slices looking like magnetic resonance Image and computed tomography so it suitable for studying anatomy at gross or macroscopic to the microscopic level (Figure 5).

Source: Ottone, N.E., Del Sol M. and Fuentes, R. (2016) Report on a Sheet Plastination Technique Using Commercial Epoxy Resin. International Journal of Morphology, 34, 1039-1043 [15] .

According to T. Shahar [13] the chemicals which are used in (generic) epoxy plastination technique and Biodur^TM E12 sheet epoxy plastination technique are the same which include:

・ Fixatives (if necessary)

・ Methylene chloride (MeCl) as defatting agents

・ Acetone

・ Epoxy resin

・ Epoxy hardeners to link the epoxy molecules

・ Epoxy plasticiser

c) Polyester plastination

The basic steps in this technique are also the same as described in the earlier procedure. In Polyester plastination the tissue fluids withdrawn and replaced by

Source: http://www1.zu.edu.eg/plastination/polyester_plastination_1_files/frame.htm

curable Polyester resin [16] such as P40 as described by von Hagens [17] , or P35 resin that has been used by von Hagens or the new comer P45 resin as described by Gao, H [18] [19] . This method is suitable to study the anatomical formation of 4 - 8 mm slices of nervous tissue [16] (Figure 6). The basic steps in polyester plastination technique are preparation of specimen, slicing and dehydration. The chemicals used according to Sargon, M.F. [8] include the following:

・ fixatives (if necessary)

・ acetone

・ methylene chloride (if necessary)

・ polyester resin.

The term of Embalming derived from Latin origin and it define as treatment of body cadavers with special chemicals so as prevent decay or putrefaction, it was an ancient culture and nowadays in modern culture it become substantial science and art due to social and science reason because the preserved body cadaver considered as an ideal teaching tool for anatomy and other branches medical science such as surgery, obstetrics, pathology and radiology [4] [20] .

a) Embalming in the ancient cultures

Many ancient cultures including Egyptian culture practiced embalming as they believed that decayed dead of the body would preclude it from life after death [21] . The basic steps of ancient embalming are:

1) Washing surface and body cavity with palm wine.

2) Removal of brain and internal organs (viscera) and keep it in jars except the heart.

3) Left the internal organ to dry.

4) Cover body with natron salt to dry.

5) After 40 days the body is wash with wine and spices.

6) Return back the organs inside the body.

7) Wrapped the body with linen.

8) Place the body inside coffin.

b) Modern embalming

As the relevance of body cadavers in anatomical studies cannot be ruled out, the embalming for preservation became more important. The process of embalming consists of four steps can be summarized as the following:

・ Arterial embalming: it is the injection of embalming fluid through the blood vessels usually the common carotid artery. This is to replace the body fluid by embalming solution.

・ Cavity embalming: this refers to substitute gas and fluid in the organ and inner side of the body with embalming fluid using a trocar.

・ Hypodermic embalming: this is a complementary step to ensure that concentrated embalming fluid reach all parts of the body, especially to those sites of body where the arterial fluids might not reached. This is done by using hypodermic needle and is a case-by-case basis step.

・ Surface embalming and washing: this is a (as needed step) remedy or treatment in damaged area in the surface which may occur due to a lot of causes such as skin diseases, cancer, decomposition or other epidermal injury.

Erich Brenner [4] in his great review article mention and compare between different types of modern anatomical embalming techniques in term of long-term storage, advantages and disadvantages and Possibilities of usage in anatomical teaching (Table 1).

The chemical components of embalming fluid used in modern embalming are variety which includes sterilization and disinfectant agents, preservatives, modifying agents (buffers, anticoagulants, and wetting agents) and dyes [4] .

The assessment of physical characteristics according to Benkhadra [39] depends on the softness and flexibility of body cadaver, and actually we get a positive result because the body cadavers maintained its softness and flexibility, that may be explained by the large amount of muscles proteins fragmentation [39] . The second part of the evaluation depends on the biomechanical testing which can be considered as acceptable in our case, taking the fact in consideration that keeping cadaver in formalin will cause a 50% stenography in energy absorption and raise the rate of bone crispness [40] and also the mechanical integrity will decrease after embalming due to bone demineralization [41] .

a) Sampling from cadaver for possible bacterial and fungal population

The samples were collected using standard swabbing procedures from different body parts of the 1) cadaver stored in 10% formalin, 2) cadaver stored in refrigerator at (0˚C - 1˚C), and 3) plastinated body parts stored at room temperature.

The swabs were taken from oral cavities, nasal cavities, upper limbs, abdomen, genital area and axilla (Figure 7, Figure 8). The swabs were aseptically plated onto Nutrient Agar (NA, CM0003, Oxoid Ltd., Basingstoke, Hampshire, England) plates and Muller Hinton Agar (MHA, CM0337, Oxoid Ltd., Basingstoke, Hampshire, England) plates. The plates were incubated at 37˚C for 48 hours (Figure 9). Also, the swabs were plated on Sabourad’s Dextrose Agar (SDA, CM0041, Oxoid Ltd., Basingstoke, Hampshire, England) plates and incubated at room temperature for up to 7 days.

b) Sampling for airborne bacteria/fungi

Sampling for possible airborne bacterial and fungal population was done in the respective rooms/labs where the specimens were kept. This is done by standard non-volumetric air sampling method. The nutrient agar and Muller Hinton agar plates were incubated at 370˚C for 48 hours and the Sabourad’s Dextrose

Agar plates were incubated at room temperature for 7 days.