Background and objectives: In patients with colorectal cancer (CRC), heterogeneous expression of Mismatch repair (MMR) proteins can manifest itself in several different forms and is not such a rare phenomenon. Therefore, it is very important to recognize the nuclear expression of MMR proteins of different MMR status in order to avoid false positive or false negative results. The aim of this study was to determine the frequency and distribution of heterogeneous expression of MMR proteins in patients with stages II and III of the disease as well as its association with clinical, demographic and pathological characteristics of CRC in relation to proficient and deficient expression of MMR proteins. Material and Methods: The study included 104 cases of colorectal cancer obtained from surgical colectomy material in stages II and III of the disease. Results: From a total of 104 patients with colorectal cancer, immunohistochemical analysis of the expression of all four MMR proteins showed that heterogeneous expression of MMR proteins (as well as deficient immunoreactivity of tumor cells) was present in 12 cases, while proficient expression of MMR proteins was detected in 80 tumors. Conclusions: Our study showed that the only independent predictors of the loss of MMR protein expression were younger patient age and right-sided anatomical location of the tumor. The study also established the existence of heterogeneous expression of MMR proteins in a non-negligible percentage of CRCs (11.5%), where heterogeneous nuclear expression of MMR proteins was described in several different forms.

In the absence of systematized data on the extracellular matrix components during prenatal liver development, the present study aimed to investigate the time of appearance and distribution of collagen types I, III, and IV and laminin. The study material included embryonic and fetal livers, aged 7–37 weeks, categorized into 3 trimesters. The material was stained using hematoxylin-eosin and immunohistochemistry methods for the identification of collagen I, III, and IV and laminin. Collagen I was detected near the end of the first trimester in the capsules and walls of interlobular veins. As the liver matures, collagen I is increasingly abundant in the capsules, portal area connective tissues, arterial walls, interlobular veins, sinusoids, and central veins. Collagen III and collagen IV appear in the middle of the first trimester in the capsules, portal areas, and walls of central veins, as well as the sinusoids particularly. In trimesters 2 and 3, these collagens are increasingly present in all the structures, but collagen IV is also present in nerve fibers. Laminin is sporadically present adjacent to the sinusoids in trimester 1, while in trimesters 2 and 3 this protein commonly appears in the walls of arteries and interlobular veins, in the basal membrane of bile ducts, and in nerve fibers. The contents of collagen I, III, and IV increase during prenatal development in the liver capsule, arterial and vein walls, sinusoids, and portal area. Laminin expression is consistent with that of the collagens with the exception that, within lobules, laminin disappears with liver maturation.

Background and Objectives: Diabetic gastroenteropathy (DG) is a common complication of diabetes mellitus type 2. Interstitial cells are non-neural cells of mesenchymal origin inserted between nerve elements and smooth muscle cells, necessary for normal function and peristaltic contractions in the gastrointestinal (GI) tract. There are at least two types of interstitial cells within the GI muscle layer—interstitial cells of Cajal (ICC) and interstitial platelet-derived growth factor receptor α-positive cells (IPC). The mechanism of diabetic gastroenteropathy is unclear, and interstitial cells disorders caused by metabolic changes in diabetes mellitus (DM) could explain the symptoms of DG (slow intestinal transit, constipation, fecal incontinence). The aim of this study was to identify PDGFRα and c-kit immunoreactive cells in the colon of rats with streptozotocin–nicotinamide-induced diabetes mellitus type 2, as well as to determine their distribution in relation to smooth muscle cells and enteric nerve structures. Materials and Methods: Male Wistar rats were used, and diabetes type 2 was induced by an intraperitoneal injection of streptozotocin, immediately after intraperitoneal application of nicotinamide. The colon specimens were exposed to PDGFRα and anti-c-kit antibodies to investigate interstitial cells; enteric neurons and smooth muscle cells were immunohistochemically labeled with NF-M and desmin antibodies. Results: Significant loss of the intramuscular ICC, myenteric ICC, and loss of their connection in intramuscular linear arrays and around the ganglion of the myenteric plexus were observed with no changes in nerve fiber distribution in the colon of rats with diabetes mellitus type 2. IPC were rarely present within the colon muscle layer with densely distributed PDGFRα+ cells in the colon mucosa and submucosa of both experimental groups. In summary, a decrease in intramuscular ICC, discontinuities and breakdown of contacts between myenteric ICC without changes in IPC and nerve fibers distribution were observed in the colon of streptozotocin/nicotinamide-induced diabetes type 2 rats.

Salivary gland tumors are neoplasms characterized by a high level of pleomorphism and histological overlap. One tumor may contain several cell types; therefore, it is necessary to include immunohistochemical staining, as well as morphometric analysis of tumor cells as prerequisites for an appropriate diagnosis. Our research included 120 tumors, such as pleomorphic adenoma, Warthin tumor, basal cell adenoma, myoepithelioma, adenoid cystic carcinoma, mucoepidermoid carcinoma, salivary duct carcinoma, polymorphous low-grade carcinoma and myoepithelial carcinoma. The aim of the study was to differentiate benign and malignant tumors based on the characteristics of nuclei. The expression of Ki67 and the morphometric nuclear parameters ? area, perimeter, Feret diameter, integrated optical density, circularity, and roundness, were analyzed. It was observed that the Ki67 proliferative index was statistically significantly higher in malignant tumors (P<0.001). Adenoid cystic carcinoma exhibited the highest value, whereas the lowest value was exhibited in basal cell adenoma. Morphometric analysis showed statistically significantly increased values of integrated optical density (P<0.001) and nuclear size parameters (P<0.05) in malignant tumors. The determination of the Ki67 proliferative index and morphometric analysis of the integrated optical density and area can differentiate benign from malignant tumors with high precision. The presented values suggest the obtained results as cut-off values.

In the reference literature, there are a few studies on the development of the lymphatic system in the liver, especially human. This study aims to establish the presence, time of appearance, distribution and representation of expression D2-40 molecule – a marker of lymph vessels endothelial cells during the fetal period of the human liver development. The livers obtained from 20 human fetuses (10 male and 12 female), aged 12-37 gestational weeks, constituted our study material. Paraffin sections, 4 µm thick, were stained with hematoxylin and eosin for histological analysis, and with LSAB2/HRP method for immunohistochemistry using the D2-40 monoclonal antibody to mark lymphatic endothelial cells. The presence of lymphatic vessels was determined by morphometry, calculating their numerical and volume density. The study showed that expression of D2-40 molecule was absent in the liver lymphatic vessels in the first trimester of development, while in the second trimester intensive D2-40 immunoreactivity was observed in the lymph vessels of the liver capsule, and low D2-40 immunopositivity of the lymph vessels in large portal spaces. In the third trimester, intensive D2-40 immunoreactivity was observed in the lymph vessels of the liver capsule and in the endothelium of numerous lymphatic vessels of various shape and size, located in the smaller and larger portal areas. Volume and numerical density of lymphatic vessels in the portal areas of the liver during fetal development increased from the second to the third trimester of pregnancy, which was proportional to the increase in volume density of the hepatic portal spaces. Based on the obtained results, a conclusion may be drawn that the lymph vessels in the liver can be identified in the first half of the second trimester, and their number was growing proportionally by the end of pregnancy.