The thesis expands and amends the scientific concepts that the stomach of white rats differs significantly from the human stomach due to the presence of additional reservoir compartment (pre-stomach), which we proposed to call the “fundal” part. It was first proved that this part performs a purely mechanical function.
Scientific data, stated that significant species peculiarities are also found in the structure of the white rat colon has been clarified. The volume of the white rat cecum is similar to the volume of the stomach; due to the peculiarities of the structure of the mucous membrane, it is precisely the part in which processes of utilization of coarse food components (fiber) occur during its fermentation. For the first time, it is shown that the first portion of the white rat colon differs in a unique configuration of the mucous membrane due to the presence of spiral-oriented folds-flutings.
The small intestine is, by morphofunctional characteristics, the only part in the white rat gastrointestinal tract, which in miniature corresponds to human one that can be a convenient object for experimental studies. The primary metric parameters necessary for further experimental study were obtained and systematized, as well as a thorough analysis of the microscopic structure of its mucous membrane was carried out.
For the first time, it was highlighted that crypts of Lieberkühn, or intestinal glands, are the essential basic structures of the mucous membrane of the entire intestine of white rats, which are legitimately considered as the structures of innate (nonspecific) immunity of the intestinal mucosa, which greatly expands the current concept of mucosa-associated lymphoid tissue (MALT).
An important point in the study of Peyer’s patches of the small intestine is that their size depends directly on the number of lymphoid nodules integrated into them by the individual modular associations of the hemomicrovasculature, among which small, medium and large sizes should be distinguished.
The findings of the studies have shown that the most controversial is the issue of the structure of the “follicle-associated epithelium”. It has been suggested to call it “lymphoid-associated epithelium” because it actually covers the lymphoid nodules but not follicles. For the first time a unique version of its structure in the form of separate columnar (fractal) formations, which in the most obvious form embodies the close connection (symbiosis) of the intestinal epithelium with lymphoid structures of Peyer’s patches was discovered. The data on the structure of the intestinal epithelium, represented by enterocytes of different specialization, among which there are specific M-cells, which play a leading role in the initiation of immune responses in the intestinal mucosa due to their ability to phagocytosis and transfer of pathogens from the intestinal contents to the immunocompetent cells of the lymphoid nodules have been clarified. The concept of M-cells which contradicts the fact that of enterocytes with phagocytizing properties in the lymphoid-associated epithelium of Peyer’s patches has been elucidated.
For the first time, the study of the structure of Peyer’s patches of white rat small intestine after oral administration of the broad-spectrum antibiotic clarithromycin revealed the novel data. It has been established that the genetically determined total amount of Peyer’s patches in the small intestine of adult white rats is constant, whereas the number of lymphoid nodules different in their generation should be considered a variable depending on the state of microbiocenosis of the intestine.
It has been established that emerging of the new primordial generations of Peyer’s patches in the small intestinal mucosa is induced by the effect of the antibacterial drug on the intestinal microflora. It is shown for the first time that primordial forms of Peyer’s patches are formed as a result of the morphogenetic transformation of the intestinal villi on the pre-formed base of the crypts of Lieberkühn, i.e., intestinal glands.
