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 formalinfixed 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.

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Ovine mastitis is considered one of the problems that cause economic losses through its impact on milk production, which is unfit for human consumption. The current study aimed to shed light on mastitis in sheep in different areas of Mosul city. The results of the recent study showed the presence of mammary macroscopic and microscopic changes. Macroscopic changes were represented by the large size of the udder and changes in the color and texture, as well as clarity of sloughing and desquamation of the skin with clear exudation, especially in advanced cases. On the other hand, other samples showed the presence of hard nodules on the udders. In contrast, the histological changes represented by degenerative and necrotic changes 3.5%, and 21.4% of the sample appeared to suffer from liquefactive necrosis and abscesses infiltrated with inflammatory cells, 25% of the samples infected with granulomatous mastitis (nodular mastitis), other models showed that the udder infected with atrophy and metaplasia in the rate of 21%, thickening of the blood vessel wall with clot represented 14.2% and the deposition of calcium salt was 14.2%. The current study concludes that mastitis in sheep is widespread in sheep raised in different areas of Mosul city.

Canine osteosarcoma is an extremely malignant bone tumor that often arises in the bones of the limbs. It is a highly metastatic disease distinguished by proliferative bone lesions and a tendency for pulmonary metastasis. Overexpression of proliferative proteins are associated with bad prognosis in human osteosarcoma. Here, we tested the expression of the different proliferative proteins (p53, p16, vimentin, and mdm2) in nine archival samples with canine osteosarcoma. Paraffin-embedded tissue sections were confirmed by histopathology and stained by immunohistochemistry for p53, p16, vimentin and mdm2. Positive expression of these proteins was evaluated as the ratio of positive cancer cells and the intensity staining was assessed in several areas. Histopathologically, 95% of samples were grade II and III. All high-grade osteosarcomas were particularly cellular. The cancer cells were generally large spindle-shaped and large nucleus with distribution of osteoid between the cancer cells. Immunohistochemical detection of p53, p16, vimentin and mdm2 was 89%, 56%, 78%, and 89% of samples respectively. The staining intensity for p53, p16, vimentin and mdm2 was particularly nuclear in 81%, 66%, 78%, and 79% of the cancer cells respectively. Our present work suggests that p53, p16, vimentin, and mdm2 were detected in grade III canine osteosarcomas samples. In addition, these proliferative markers are the significant biomarkers in canine osteosarcomas and can be used as a predictor for diagnostic and prognostic value and allowing cancer differentiation. This primary data supports that both canine and human osteosarcomas share same molecular characters which are approved by expression of proliferative genes.

The current study aimed to determine the pathological effects of chronic poisoning with sodium fluoride on some reproductive organs like ovary, and testis of adult's male and female albino rats. Thirty-six male and female adult's albino rats were divided into six groups. The first and second group of male and female rats are control groups was given tap drinking water, the third and fourth groups of male and female rats was given 150 ppm of NaF, the fifth and sixth group of male and female rats was given 300 ppm of NaF respectively for 90 days. The weights of male and female genital were recorded. Histological exam of control groups of female rats showed the typical histological structure of the ovary, while the NaF treated groups showed a decrease in growing follicles, in addition to thickening in tunica albuginea and deposition of eosinophilic material. In male control groups, the sections showed the typical histological structures of the testis, while the treated groups showed multinucleated spermatids in addition to the deposition of amorphous eosinophilic material in the interstitial tissue, coagulative necrosis, in addition to apoptotic and sloughed spermatogonia in the lumen of seminiferous tubule. These results indicate that sodium fluoride with 300 ppm has toxic effects on organ body weights and on the histology of the gonads of adult's male and female albino rats.

Respiratory system disease is common in sheep, which is frequently difficult to detectable in live animals until it becomes serious and complicated. This study was aimed to describe sheep lung lesions in Mosul city, which roam in dump zones and have been slaughtered at butchers' shops, fifty male and female sheep 1-5 years were used at the current work from March to December 2021; affected Samples were collected and prepared for standard histopathological analysis. The special stain was also used for carbohydrates demonstrated inside and around lung lesions. The results of the current study showed the presence of gross and histological finding changes, the gross lesion presented by inflammation of the upper right lope, congestion, and bleeding on all parts of the lope in addition to different sizes of the nodular lesion. In contrast, the pneumonic histological finding was 12.1%, circulatory disturbance 3.5%, parasitic infections 10.0%, disturbance of growth 7.1%, Necrotic area surround by swirling macrophage 2.0% in addition to the deposition of calcium salt and hemosiderin pigmentation. Organizing Pneumonia (OP) and Masson's bodies were one of the most detected lesions in the roaming sheep, it was scored by Masson Trichrome from mild, moderate, and severe fibrosis. All lesions were categorized according to the type of lesion, grade, and kind of it. From the current work, we demonstrated that pneumonic disorder represented a considerable and serious problem in the animal livestock industry and leads to economic loss in milk, wool, and sheep meat production. Additional studies are recommended to determine the etiological agent of sheep lung lesions whether it is a fungal, bacterial, or viral agent.

Johne's disease is an international healthiness problem affecting ruminants.It is caused by Myobacterium avium spp. paratuberculosis (MAP). It has serious production-limiting important and also caused significant cost-effective loss in flocks due to direct impact on delayed/reduced breeding, infertility, culling, mortality, and milk reduction. This disease is problematic to diagnose because of elongated incubation times. Proof of identity this disease subclinical can shed the organism as a source of infection for other herds; so, it is critical for control. The present study deals with the morphological (grossly, histopathologically and histochemically) characterization of the disease in cattle. The corpse appears hidebound with sunken eyes and with persistent and non-responsive diarrhea. The necropsy of visceral showed gelatinization and outlying fat. Grossly chiefly pathological alterations in digestive tract such as severe congested of small intestine with marked thickening of its wall a combined with enlargement of mesenteric lymph nodes and gallbladder appear distension with severe thickening walls and blood mixed with bile. Histopathological examinations revealed severe infiltrations of inflammatory cells such as macrophages, lymphocytes, and epithelioid cells with multiple langhans giant cells in bowel layers and mesenteric lymph nodes with diffuse lepromatous reaction were observed in these lymph nodes and other organs like liver, tonsils and kidney.