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OBJECTIVES: The ependymal lining of the human brain ventricular system displays distinct structural differences and functional heterogeneity among individual ependymal cells (ECs). To date, multi-ciliated ECs (E1 cells), bi-ciliated ECs (E2 cells), uni-ciliated ECs (E3 cells), ECs without cilia, and ECs with cytoplasmic protrusions have been described in human brain ventricles. METHOD: Using scanning electron microscopy (SEM), we evaluated ependymal samples from 6 defi ned regions of the third ventricle from 9 human brains. These regions were strictly defi ned according to the periventricular structures they neighbour with. RESULTS: We observed different structures on the apical surface of the ECs. Various ECs differed from each other by the presence of microvilli, secretory bodies, and a variable number of cilia, which led us to divide the ECs into several exactly specifi ed types according to their apical morphology. CONCLUSION: We found all types of ECs in every examined region with a predominance of particular types of apical surface of ECs in the individual areas (Tab. 4, Fig. 7, Ref. 22).

Knowledge about the three-dimensional fine structure of human heart, as a crucial vital organ of the body, is not only fascinating from the scientific or educational points of view, but has a very important clinical impact. Therefore, we decided to create a three-dimensional atlas of fine structure of the human heart. Tissue samples from ten human hearts were rinsed in phosphate-buffer solution, fixed by glutaraldehyde buffered solution, and post-fixed in osmium tetroxide solution. A gentle dehydration with ethanol in different concentration and drying at the critical point of CO

The aim of our research was to identify Merkel cells in stratified squamous nonkeratinized epithelium of the human oesophagus. We chose the middle and lower part of the oesophagus. For identification of Merkel cells we used antibodies against simple-epithelial cytokeratines, especially anti CK 20, because it is providing the highest degree of specificity. Our investigation showed increased number of CK 20-positive Merkel cells in lower (distal) part of the oesophagus, approximately 60%. In the middle part of the oesophagus there were 30% of CK20-positive Merkel cells.

Reproductive immunology is at the forefront of research interests, aiming to better understand the mechanisms of immune regulation during gestation. The relationship between the immune system and the implanting embryo is profound because the embryo is semi-allogenic but not targeted by the maternal immune system, as expected in graft-versus-host reactions. The most prominent cell population at the maternal–fetal interface is the population of uterine natural killer (uNK) cells. Uterine NK cells are two-faced immunologically active cells, bearing comparison with Janus, the ancient Roman god of beginnings and endings. Their first face can be seen as natural killer cells, namely lymphocytes, which are critical for host defense against viruses and tumors. Even though uNK cells contain cytolytic molecules, their cytotoxic effect is not applied to classical target cells in vivo, playing a permissive rather than a defensive role. Their second face is crucial in maintaining physiological gestation—uNK cells show critical immunomodulatory functions with the potential to control embryo implantation and trophoblast invasion, regulate placental vascular remodeling, and promote embryonic/fetal growth. Therefore, we believe that their current designation “natural killer cells” (the first “cytotoxic” Janus’s face) is misleading and inappropriate, considering their principal function is supporting and maintaining pregnancy. In this narrative review, we will focus on three lesser-known areas of knowledge about uNK cells. First, from the point of view of histology, we will comprehensively map the history of the discovery of these cells, as well as the current histological possibilities of their identification within the endometrium. To be brief, the discovery of uNK cells is generally attributed to Herwig Hamperl, one of the most influential and prominent representatives of German pathology in the 20th century, and his co-worker, Gisela Hellweg. Secondly, we will discuss the interesting aspect of terminology, since uNK cells are probably one of the human cells with the highest number of synonymous names, leading to significant discrepancies in their descriptions in scientific literature. From the first description of this cell type, they were referred to as endometrial granulocytes, granular endometrial stromal cells, or large granular lymphocytes until the end of the 1980s and the beginning of the 1990s of the last century, when the first publications appeared where the name “uterine NK cells” was used. The third area of present review is medical teaching of histology and clinical embryology. We can confirm that uNK cells are, in most textbooks, overlooked and almost forgotten cells despite their enormous importance. In the present narrative review, we summarize the lesser-known historical and terminological facts about uNK cells. We can state that within the textbooks of histology and embryology, this important cell population is still “overlooked and neglected” and is not given the same importance as in fields of clinical research and clinical practice.

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The aim of this work is to describe the structure of the thymus, especially its medullary part, in children with congenital heart defects. It is known that development of the thymus and the heart is also influenced by neural crest cells. During the early development of the heart and the thymus cells proliferate and migrate to their primordia. It is known that inadequate cephalic neural crest contribution during development of pharyngeal pouch derivatives results in defective organogenesis of the face, the thymus, parathyroid glands and also the heart. We studied the structure of the thymus in children with congenital heart defects from 0 to 12 years of life at light microscopic and electron-microscopic levels. Thymuses of the patients were surgically removed in the Children's Cardiocenter in Bratislava. The results of our study confirmed the differences in the medullary structures of thymuses with chosen diagnoses. Hassall's corpuscles in the thymic medulla were various in size and also in structure and number. The special structures of the thymic medullary region in children with ventricular septal defects and defects of outflow of the heart were big cystic Hassall's corpuscles. In comparison with a size of Hassall's corpuscles in normal thymuses the size of Hassall's corpuscles in studied thymuses suprisingly ranged between 100-250 µm.

This article summarizes the importance of the exact morphology of human uterine/fallopian tube epithelium at the scanning electron microscopy (SEM) level for the clinical outcome even nowadays. Visual referential micrographs from SEM reflect two ways to view human epithelial cell lining surfaces: the surface epithelial uterine tube from surgical tissue biopsy and human fallopian tube epithelial cells (HFTEC) culture monolayer surface. One colorized image visualizes ciliated cells, distinguishes them from non-ciliated cells, and provides an educational benefit. A detailed description of the ultrastructure in referential and pathologic human uterine tube epithelium is important in defining the morphological basis of high-grade carcinomas, in the mechanism of pathophysiology, and in discussing options for its prevention. Cell cultures of human fallopian tube epithelial cells offer new approaches in simulating the mechanisms of cancer genesis or may help to elucidate the genetic basis of several diagnoses. New technical approaches in SEM provide higher resolution and detailed surface images. The SEM modality is still one of the current options in diagnostics and may be useful for advancing human reproductive organ cancer research.