Light and Electron Microscopy of the European Beaver (Castor fiber) Stomach Reveal Unique Morphological Features with Possible General Biological Significance

Abstract

Anatomical, histological, and ultrastructural studies of the European beaver stomach revealed several unique morphological features. The prominent attribute of its gross morphology was the cardiogastric gland (CGG), located near the oesophageal entrance. Light microscopy showed that the CGG was formed by invaginations of the mucosa into the submucosa, which contained densely packed proper gastric glands comprised primarily of parietal and chief cells. Mucous neck cells represented <0.1% of cells in the CGG gastric glands and 22–32% of cells in the proper gastric glands of the mucosa lining the stomach lumen. These data suggest that chief cells in the CGG develop from undifferentiated cells that migrate through the gastric gland neck rather than from mucous neck cells. Classical chief cell formation (i.e., arising from mucous neck cells) occurred in the mucosa lining the stomach lumen, however. The muscularis around the CGG consisted primarily of skeletal muscle tissue. The cardiac region was rudimentary while the fundus/corpus and pyloric regions were equally developed. Another unusual feature of the beaver stomach was the presence of specific mucus with a thickness up to 950 µm (in frozen, unfixed sections) that coated the mucosa. Our observations suggest that the formation of this mucus is complex and includes the secretory granule accumulation in the cytoplasm of pit cells, the granule aggregation inside cells, and the incorporation of degenerating cells into the mucus.

Temporospatial characterization of the bronchus associated lymphoid tissue (BALT) of the one humped camel (Camelus dromedarius)

“…The ordinary low dense portion of the granule was predominating. This mucous was observed only in the gastric epithelium of European beaver ( Castor fiber ) (Ziolkowska et al 2014 ) who described it as a unique morphological feature with possible general biological significance. More biochemical investigation may explain its role.…”

Development of a quantitative prediction algorithm for target organ-specific similarity of human pluripotent stem cell-derived organoids and cells

“…For example, StGEP presented a total gene expression panel consisting of region-specific genes from the fundus and antrum. The fundus and antrum regions of the stomach have different functions, and cell-type-specific gene expression corresponds to distinct cell types 40 . There is a report of hPSC-derived GOs that contain either antral or fundic epithelium 41 .…”

Mucus models to evaluate the diffusion of drugs and particles

“…These non-aqueous fixatives may aid in maintaining the mucus structure by different mechanisms, e.g., minimizing water movement out of the gel or mitigating surface tension effects[221]. Cryopreservation can also be utilized to preserve the mucus layer[224], and has been used to enable visualization of mucus thickness[225], mucus proteins[226], goblet cells[227], and particle distribution[228]. Non-fixed and fixed mucosal tissue samples may be embedded in optimal cutting temperature (OCT) compound, snap frozen in isopentane cooled with liquid nitrogen, and then sectioned.…”