Histopathology considered as an essential keystone to understanding diseases on a cellular level, without examining affected tissues and cells; will lack the accurate diagnosis. The most common protocol that used worldwide for histopathology is termed as formalin-fixed paraffin-embedded techniques; this protocol is the oldest protocol and still used, this technique not invented once, but it is started with a simple process of tissue fixation then undergo several successful steps as it's known today. This protocol depends on formalin to induce tissue fixation and preservation simultaneously, followed by a series of steps to facilitate infiltration of hot paraffin wax in the cells to adjust the density of tissue similar to that of paraffin wax to support tissue during sectioning process at few micrometers of thickness. Many protocols have been invented and modified subsequently to increase the accuracy of tissue processing and facilitate their study under light microscopy. Additionally, the formalin-fixed and paraffin-embedded samples can be considered the most durable process till now. In this review, we are trying to view all fundamental aspects of classical tissue processing that was depended since 1850s, starting from tissue examination, sampling, accessory, labelling, fixation, dehydration, clearance, infiltration, and embedding with hot paraffin wax. Additionally, explain the routine sectioning and staining with classical Hari’s hematoxylin and alcoholic eosin staining protocol.

In present study we aimed to introduce modifications in classical protocol applied to stain collagen fibers by Masson's trichrome stain, in order to decrease time and concentration of different steps and chemical in this traditional protocol. The experiment design contains a series of successive amendment steps based on previously successful steps, in which every step where be modified to get the best result, then the next step of staining protocol will be modified in the classical Masson's trichrome staining protocol in a samples of tissue from liver, heart and intestines of sheep diagnosed with chronic fasciolosis. The result showed that the new modified protocol gives the same staining efficiency to collagen fiber when we used Harris hematoxylin as a nuclear strainer or even excluded this stain from staining protocol. In conclusion this new modified staining protocol give a perfect staining reaction to collagen fibers in pathological samples which is similar to that obtained by Masson's trichrome stain, also this new modified procedure is less time consuming and less toxic effect on human and environment than other trichrome stains, and can be easily conducted either by the technician or the pathologists.

This study was performed to evaluate pathology of experimental Encephalitozoon cuniculi (Iraqi isolate) infection in normal and immunosuppressed mice. Pathological changes were not seen in negative control mice while secondary bacterial infections were noted in the lungs, kidneys, and heart of mice given dexamethasone. Typical E. cuniculi infection lesions were found in brain, livers, lungs, and kidneys of mice given 10⁷ E. cuniculi spores/mouse orally. These lesions were in the form of nonsuppurative meningoencephalitis with vasculitis in brain, interstitial inflammation with infiltration of both lymphocytes and plasma cells in lung tissue, and nonsuppurative interstitial (focal and diffuse) nephritis, presence of vacuole containing mature and immature spores in enterocytes within the tips of villi, and lymphoiod hyperplasia of the white pulp and vasculitis of the intratrabecular vessels. Mice that were given 10⁷ E. cuniculi spores/mouse orally showed lesions similar to those observed in the previous group (vasculitis and granulomas) but the lesions were more severe and widespread. In conclusion, this is the first report of experimental E. cuniculi infection induced by E. cuniculi isolated from a naturally infected rabbit in Iraq and that infection became more severe and widespread upon the administration of dexaethasone.

Current study aimed to identify the gross and microscopic lesions and their percentage in liver of cattle slaughtered in Kirkuk province abattoir. A total of 6211 liver sample were examined during period from 01/08/2016 until 01/12/2016 with total cattle liver that showed gross lesions 738 cases. A gross examination was applied to affected liver and tissue sample were taken from lesions for histopathological examination. The result of current study showed that the total liver lesions in cattle is about 11.88% (738/6211) which distributed as liver fluke infestation 3.34% (213/6211), hydatid cyst 3.12% (194/6211), liver abscess 2.29% (142/6211), cholangiohepatitis 2.01% (125/6211), and hepatic hemorrhage with congestion 1.03% (64/6211). The results of gross and microscopic examination of liver infested with liver fluke showed presence of thickening in bile ducts with adult fluke as well as liver atrophy with hyperplasia of epithelial cell in affected bile ducts with dystrophic calcification. While in case of hydatid cyst the lesions composed from presence of larval stage in form of white cyst in different size and their walls composed from hyperplasia of fibrocytes and fibrin strands. In case of hepatic hemorrhage and congestion the result showed sever congestion with staining of liver tissue by blood color, with presence of red blood cells in association with inflammatory cells between hepatocytes. While in case of hepatic abscess we noticed presence of white to yellow solid lesions that randomly distributed in different shape and size composed from necrotic center with infiltration of mononuclear inflammatory cells and hyperplasia of fibrocytes. While in case of cholangiohepatitis the affected area showed paleness with accumulation of bile material inside bile ducts, as well as hyperplasia of affected ducts and fibrosis in portal areas with infiltration of mononuclear inflammatory cells in liver tissue with dystrophic calcification in bile ducts. We concluded from current study that wide spread of hepatic lesions in liver of cattle in Kirkuk province and this result should be taken in more serious action which can result in economic losses as well as possibility of zoonosis of these pathogens to human, also the gross lesions described by current study were identically similar to microscopic lesions.

The current study aimed to explain propolis's protective effect on the liver and kidney damage caused by methotrexate (MTX). A total of 80 chickens at one day old were used and divided into three groups; the first group was the control group, the second group received the propolis, the second group was treated with MTX, and the fourth group received both propolis and treated with MTX. After 15 days of experimental, all chickens were euthanized, and blood samples and liver and kidney tissue were collected. The result showed that the treated group with MTX showed an increase in serum levels of AST, ALT, AP, urea, creatinine, and uric acid in comparison with both the control and propolis group, while in the group treated with both Propolis and MTX showed serum level of AST, ALT, AP, urea, creatinine, and uric acid similar to that recorded in both in the control group and MTX group. The liver sections treated with methotrexate showed hyperplasia of fibrocytes in the portal area with infiltration of mononuclear inflammatory cells represented by macrophages, and coagulative necrosis in affected hepatocytes, clear vacuoles in the hepatocytes, massive infiltration of macrophages. Sections of the liver treated with methotrexate and propolis explain a marked decrease in fatty degeneration, with few infiltrations of mononuclear inflammatory cells around portal areas. The liver section from the propolis-treated group and the control group showed typical hepatic tissue architecture. The kidney sections treated with methotrexate showed coagulative necrosis in the endothelial cells, glomeruli appearing irregular in shape, and hemorrhaging in the extracellular matrix. The sections of the kidney treated with methotrexate and propolis explain a marked rise in the renal tubules with the typical feature of a healthy one. The section of the kidney from the propolis treated group and control group showed typical architecture of renal tissue. In conclusion, propolis greatly protects against MTX's toxic effect on chicks' liver and kidneys.

Fasciolosis cause economic losses in cattle that breed in Iraq and the world. About 4% of bovine liver’s samples included in the current study exhibited classical pathological lesions of fasciolosis. Samples of cattle livers infected with fasciolosis were taken for histopathology. Eighteen grading criteria with four scoring level have been chosen to grading the microscopic lesions caused by Fasciola hepatica into a mild infection (grade I), moderate infection (grade II) and severe infection (grade III). The type of hepatic degeneration or necrosis, cloudy cell swelling, coagulative necrosis, infiltration of inflammatory cells, with patterns of infiltration, also type of infiltrated cells, fibrosis between hepatic cells or in portal area, affection to hepatic cords arrangement, hepatic sinusoids, extensions of hemorrhage, pigment deposition, hyperplasia of bile duct, thickness of hepatic capsule and presence of liver fluke were the main grading levels. In grade, I the microscopic lesions were characterized by simple or mild in their nature with very good reversible prognosis, while grade II characterized by moderate severity of the lesions with a good reversible prognosis, while grade III characterized by hostile severity with bad irreversible prognosis as a result of architecture changes in liver histology. In conclusion, we believed that this grading system could be used as a guide when examining histopathological liver's samples infected with F. hepatica to identify the stage of infection and proposed an accurate prognosis.