The structural characteristics of photoaging in mice caused by the effects of ultraviolet A radiation.

BACKGROUND: Due to its deep penetration into the dermis, ultraviolet A (UVA) radiation is considered a primary factor in skin photoaging. The aim of this study is to use a qualitative and quantitative analysis to determine the structural parameters of skin photoaging in mice exposed to UVA radiation, with or without the application of a photoprotective cream. MATERIAL AND METHODS: The experiment consisted of the radiation of female BALBc mice in a solarium by UVA rays, up to total dosages of 7800 J/cm² and 12500J/cm². A total of 78 animals were divided into 4 experimental and 2 control groups. All animals were shaved and the animals in 2 experimental groups were treated with a photoprotective cream half an hour before exposure. The samples of the treated skin were stained with Hematoxylin-eosin and Van-Gieson staining methods. All measurements, except for the presence of dyskeratosis, were taken using ImageJ 150i software. RESULTS: In the study, the signs of skin photoaging were more evident in untreated groups of animals. Dysceratosis was more frequent in both of the untreated groups of animals (p=0.004) and (p=0.003). The lowest values of epidermal thickness (13.8± 2.6µm and 12.7±2.3µm) were present in both of the untreated groups of animals (p<0.001) and (p<0.001). The highest values of stratum corneum thickness (34.3±8.5µm) were observed in the untreated, shorter radiated group of animals (p<0.001) which was irradiated for the shortest period of time. Beside the control groups, the highest length of dermo-epidermal junction (DEJ) was recorded in the group of treated, longer radiated animals (1467.6±94.6µm) (p=0.373). The lowest values of dermal thickness (115.9±10.5µm and 134.8±21.8µm) and volumetric density of the collagen fibers (31.92±3.19% and 29.40±4.54%) were present in both untreated groups of animals (p<0.001), (p<0.001), (p=0.035). CONCLUSIONS: Skin photoaging was most pronounced in the groups of animals irradiated without the application of photoprotective cream.

Quantitative morphometric analysis of the myenteric nervous plexus ganglion structures along the human digestive tract.

BACKGROUND/AIM: All the functions of the digestive system are controlled, guided and initiated by the autonomic nervous system. A special part of this system placed in the wall of the gastrointestinal tract is known as the enteric or metasympathetic nervous system. The aim of this study was to analyse myenteric nervous plexus in different parts of the digestive tract. METHODS: We examined the myenteric nervous plexus of the esophagus, stomach, duodenum, jejunum, ileum, transverse colon and rectum in tissue samples taken from 30 cadavers of persons aged 20-84 years. After standard histological processing sections were stained with hematoxylin-eosin, cresyl violet (CV) and AgNO3 method. Multipurpose test system M42 was used in morphometric analysis. The results were analyzed by t-test and analysis of variance. RESULTS: The number of neurons per cm² surface was the lowest in the esophagus (2.045 ± 310.30) and the largest in the duodenum (65,511 ± 5,639). The statistical processing showed significant differences (P < 0.001) in the number of neurons between the esophagus and all other parts of the digestive tract. The maximal value of the average surface of the myenteric nervous plexus neurons was observed in the esophagus (588.93 ± 30.45 µm²) and the lowest in the stomach (296.46 ± 22.53 µm²). CONCLUSION: There are differences in the number of ganglion cells among different parts of the human digestive tract. The differences range from a few to several tens of thousands of neuron/cm2. The myenteric nervous plexus of the esophagus was characterized by a significantly smaller number of neurons but their bodies and nuclei are significantly larger compared to other parts of the digestive tract.

Age-related structural changes in the myenteric nervous plexus ganglion along the anterior wall of the proximal human duodenum--a morphometric analysis.

BACKGROUND/AIM: Aging is one of the most complex biological processes which probably affect structure and function of the enteric nerve system. However, there is not much available information on this topic, particularly in humans. The aim of this study was to investigate the influence of aging on the structure of the myenteric ganglia in the anterior wall of the human proximal duodenum. METHODS: We examined the myenteric ganglia in the proximal duodenal anterior wall specimens obtained from 30 cadaver persons aged from 20 to 84 years. Tissue samples were classified into three age groups: 20-44, 45-64 and 65-84 years. After standard histological preparation, specimens were stained with HE, Cresyl Violet and AgNO3. Morphometric analysis of all the specimens, using a multipurpose test system M42, was performed. The data were subjected to the t-test. RESULTS: The myenteric ganglia of very old humans contains an empty space, i.e. the respective parts of ganglia show a decreased number of neuron as compared to younger population. The average number of neuron per cm2 of the duodenum in the youngest people (20-44 years) was 69,370 +/- 1,750.00, in the people aged 45-64 years 69,211 +/- 1,573.33, and in the oldest persons (65-84 years) 57,951 +/- 1,291.52. The loss of neurons in the oldest persons was 16.46%. The applied statistic test demonstrated a significant difference between the observed groups (p < 0.0001). CONCLUSION: Aging does not induce changes in size and surface of neurons in the ganglia, but it decreases the number of neurons. The nerve structures in the elderly are partly emptied of bodies of nerve cells ("empty ganglions"), which indicates the existence of changed myenteric ganglia in the duodenum. These changes could be related to the duodenum motility disorder associated with aging.

Asymmetries in numerical density of pyramidal neurons in the fifth layer of the human posterior parietal cortex.

BACKGROUND/AIM: Both superior parietal lobule (SPL) of dorsolateral hemispheric surface and precuneus (PEC) of medial surface are the parts of posterior parietal cortex. The aim of this study was to determine the numerical density (Nv) of pyramidal neurons in the layer V of SPL and PEC and their potential differences. METHODS: From 20 (40 hemispheres) formaline fixed human brains (both sexes; 27- 65 years) tissue blocks from SPL and PEC from the left and right hemisphere were used. According to their size the brains were divided into two groups, the group I with the larger left (15 brains) and the group II with the larger right hemisphere (5 brains). Serial Nissl sections (5 microm) of the left and right SPL and PEC were used for stereological estimation of Nv of the layer V pyramidal neurons. RESULTS: Nv of pyramidal neurons in the layer V in the left SPL of brains with larger left hemispheres was significantly higher than in the left SPL of brains with larger right hemisphere. Comparing sides in brains with larger left hemisphere, the left SPL had higher Nv than the right one, and then the left PEC, and the right SPL had significantly higher Nv than the right PEC. Comparing sides in brains with the larger right hemisphere, the left SPL had significantly higher Nv than left PEC, but the right SPL had significantly higher Nv than left SPL and the right PEC. CONCLUSION: Generally, there is an inverse relationship of Nv between the medial and lateral areas of the human posterior parietal cortex. The obtained values were different between the brains with larger left and right hemispheres, as well as between the SPL and PEC. In all the comparisons the left SPL had the highest values of Nv of pyramidal neurons in the layer V (4771.80 mm(-3)), except in brains with the larger right hemisphere.