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Aim: In this study, histological changes in stomach during prenatal and postnatal development were examined. Material and Methods: In this study, 34 female Wistar Albino rats weighing 200-250 g, obtained from Inonu University Experimental Animal Research Lab were used. Stomach samples obtained from prenatal 7,10,14,17, 20 days old fetuses and from postnatal 5,10,15,20 days old newly born and young adult rats were prepared by routine tissue proceeding procedure and examined by light microscopy. Results: In prenatal period, the stomachs of 7,10,14 days old rats were surrounded by stratified columnar or pseudostratified columnar epithelium. Mesenchymal connective tissue surrounded the epithelium. A circular oriented muscle layer was formed in mesenchyme in prenatal 17 days old rats. In prenatal 20 days old rats, extension of the lumen, thickening of the wall, appearance of the foveola and gland-like structures were observed. Epithelium was transformed into simple columnar epithelium in various places. Mucous neck cells in the gland epithelium and outermost serosa layer were identified. On postnatal 5th day, parietal and chief cells could be detected in tubular gastric glands. Myenteric plexus was observed between two muscle layers. On postnatal 10th day, mucus layer was observed on the surface. In subsequent periods, histological properties of stomach were changed and gained adult stomach's properties. Results: It was investigated in which prenatal and postnatal periods the histological features of the stomach of an adult rat were acquired. The obtained data of this study will guide the other related studies. [ABSTRACT FROM AUTHOR]

Reticular cells are fibroblast-like cells that synthesize reticular fibers. They are stellate in shape. Elongated cytoplasmic processes of these cells wrap around the bundles of reticular fibers, effectively isolating these structural components from the parenchma of the lymphatic tissue and organs. Besides their supporting role, they express surface molecules and produce substances that attract T cells, B cells and dendritic cells. Reticular cells have been subdivided on the basis of their location and phenotype into 3 major subsets: fibroblastic reticular cells, dendritic reticulum cells and interdigitating reticulum cells. Fibroblastic reticulum cells have many ultrastructural characteristics of fibroblasts but differ from them in containing prominent bundles of microfilaments and in reacting strongly with antibodies to smooth muscle type myosin and actin. Dendritic reticulum cells are present in lymph follicules of lymph nodes, spleen, and tonsils. These antigen presenting cells are characterized by numerous cytoplasmic processes extending (dendrits) between adjacent lymphoid cells. Dendritic retikulum cells are known as a key cell of the germinal center microenvironment. These cells acquire and maintain antigen-antibody complexes and can stimulate memory B cells that can, in turn, stimulate further T cell activity. Interdigitating reticulum cells are arachnoid nonlymphoid accessory cells found in the T-cell areas of peripheral lymphoid tissue. They are potent antigen-presenting cells responsible for initiating primary T-lymphocyte immune responses-----------------Six types of epithelial reticular cells were observed in thymus: type I (subcapsular-perivascular), type II (pale), type III (intermediate), type IV (dark), type V (undifferentiated) and type VI (large-medullary).--------In this review, the microscopic and functional characteristics of reticulum cells are summarized. [ABSTRACT FROM AUTHOR]

Clara cells firstly identified as a distinct cell type by Kolliker in 1881 are non-ciliated secretory cells located in the small airways. These cells can be easily identified by their distinct dome-shaped morphology and numerous secretory granules among the other epithelial cells. The distribution of Clara cells throughout the respiratory system is in a species-specific manner. These cells have several lung protective functions. Clara cells, basically function in lung homeostasis, play roles in xenobiotic metabolism and immune system regulation. In humans, many forms of lung cancer originate from Clara cells. The aim of this review was to give information about morphological and function features of the Clara cells. [ABSTRACT FROM AUTHOR]