No abstract

To study the quantitative and qualitative mucins profile of gastroesophageal zone (GEZ) epithelium during stages of the embryonal and fetal ontogenesis periods we have performed morphometrical and histochemical researches of the gastroesophageal junction (GEJ) epithelial differon. The current study was carried out on 169 human embryos and fetuses of gestational age from 4–5 till 38 weeks. It was established that during early embryonal period (5–6 weeks) gradual increase of neutral and acid mucins in esophageal part of the GEJ epithelial differon is observed. For early fetal period (10–28 weeks) disappearance of acid syalomucins in the GEJ enterocytes from 10 till 18 week and increasing of neutral mucin till 7,65±0,18% with falling of its level in 18–20 weeks period and decreasing till 2,4±0,10% in 28 weeks (р<0,001) was typical. Late fetal period from 28 till 38 weeks is characterized by complete structural rearrangement of epithelial differon of the GEZ stratified squamous nonkeratinized epithelium with formation of two functional zones: protective germinative in esophageal part of GEJ with incomplete histochemical cytodifferentiation of the GEJ esophageal epithelium. It was proved by remains of acid mucins (syalomucins) which are untypical for mature esophageal epithelium. Thus, the obtained data on the histological features of the GEZ epithelial differon in the prenatal period of ontogenesis will improve the accuracy of diagnosis and assessment of pathological changes in the mucous membrane of the GEJ.

In order to study the quantitative and qualitative composition of mucins of the gastroesophageal zone (GEZ) epithelium during the stages of embryonic and fetal periods of ontogenesis, we conducted morphometric and histochemical studies of the epithelial differon of the gastroesophageal junction (GEJ). The early embryonic period of 5–6 weeks was established to have been observing a gradual increase of neutral and acid mucins secretion in the gastric parts of the GEJ epithelial differon whereas the embryo-fetal or non-fetal period from 7 to 9 weeks was characterized by changing and the structural rearrangement of the epithelial differon and sulfomucins appearance in gastric epithelium and gradual decrease in the production of acid mucins. The early fetal period (10–28 weeks) is characterized by disappearance of acid sialomucins in the enterocytes of the GEZ from 10 to 18 weeks and an increase to 7.65±0.18% of neutral mucins with a drop in their level in the 18-20 week period and a decrease to 24±0.10% at 28 weeks (p<0.001). The late fetal period, from 28 to 38 weeks, was characterized by a complete structural rearrangement of the epithelial differon of the GEZ with the formation of a simple columnar epithelium of the cardiac part of the stomach with incomplete histochemical cytological differentiation of the GEZ gastric epithelium. It was evidenced by the presence of residual acid mucins (sialomucins) that are not typical for mature gastric epithelium.

The source of the origin of the epithelium of the cardiac part stomach mucosa has been repeatedly discussed in the literature and different variants of the transformation of the epithelium as manifestation of normal anatomical peculiarities of a man and as a result of changing the program of stem cell differentiation, migration of bone marrow cells, transdifferentiation of simple columnar epithelium have been proposed. Probably it is related to difficulties of studying insignificant in size epithelium of the cardiac mucosa itself and establishment of connection of the duodenogastroesophageal reflux with the development of metaplasia in the epithelium of the terminal department of the esophagus mucosa, which resembles its structure in the cardiac part of the stomach. The purpose of the research was to study the expression of the transcription factor Sox2 and the distribution of cytokeratins in the epithelium of the gastroesophageal zone during the stages of the embryonic and fetal periods of ontogenesis. According to the purpose of the research, an immunohistochemical analysis of the epithelial differon of the esophageal-gastric junction (GEJ) was used. The current study was carried out on 169 human embryos and fetuses of gestational age from 4-5 till 38 weeks. It was established that the transcription factor Sox2 is expressed in basal epitheliocytes of GEJ in all terms of observation and plays a major role in the development, differentiation and formation of the epithelial cell lineage of GEJ. The peculiarity of expression of cytokeratin 7 was positive marking in the cytoplasm of spinosum epitheliocytes, despite the negative expression in the basal layer. It showed weak expression in the epitheliocytes of the esophageal part of the GEJ in the embryonic period with an increased reaction in the embryo-fetal period and with subsequent disappearance, starting at 14 weeks in the early fetal period. For the cardiac mucous membrane GEJ was characterized by its moderate expression on all terms of observation. Cytokeratin 8/18 is embryo-fetal for the esophageal part of the esophagus, as it is defined in early periods of embryogenesis and disappears in the late period (28-38 weeks). For the cardiac mucous membrane GEJ was characterized by its moderate expression on all terms of observation. Cytokeratin 14, unlike CK7 and CK8/18, was localized in the cytoplasm and membranes of basal epitheliocytes of the esophageal part of the mucosa from the 17 gestational weeks and was absent in the gastrointestinal part of the GEJ throughout the prenatal period. Thus, our data on the expression of the transcription factor Sox2 and cytokeratins in the GEJ epithelial differon in the prenatal period of ontogenesis will improve the diagnostic accuracy in determining tissue or organ belonging and can be widely used in various GEJ diseases.