Intraepithelial hyaline globules (thanatosomes) occurring in the gut of a Rhina ancylostoma

Introduction: In human medicine hyaline globules (thanatosomes) have been described in various cell types and tissues and associated with normal, nonneoplastic, and neoplastic disorders, representing a well-defined morphological and functional entities related to degeneration and apoptosis. Methodology: Tissue samples from various organs of an adult Rhina ancylostoma suffering of systemic bacterial infection died from sepsis were collected for histological analysis. 3-μm-thick sections were stained with haematoxylin-eosin (HE) and periodic acid–Schiff (PAS). In addition, sections of intestine were selected for immunohistochemical analysis by an avidin–biotin–peroxidase-complex (ABC) technique for cytokeratins AE1/AE3. Results: Histopathological analysis revealed the presence of numerous hyaline globules within the cytoplasm of intestinal epithelium as discrete or prominent, spherical or ovoid, eosinophilic amorphous globular bodies, filling the cytoplasm. Thanatosomes stained positively for cytokeratins AE1/AE3 and were weakly PASpositive. Conclusions: There have been no published reports to date of hyaline globules in the gastro-intestinal epithelium of a fish species nor hyaline globules are reported as common background findings of gastrointestinal epithelium in fish histopathology studies. Thanatosomes have been reported in the gastrointestinal epithelium of humans with various disorders. In veterinary medicine intracytoplasmic hyaline globules of neurosecretory origin have been reported sporadically in the adrenal medulla of laboratory animals dying of polychlorinated biphenyl or dioxin toxicosis, severe bacterial infections, or unknown causes and as ganglionic inclusions in captive coatis. In this case the hyaline globules were present only in the intestinal epithelium. Although thanatosomes are a nonspecific microscopic phenomenon, they represent a relatively constant and useful histologic marker of enhanced cell turnover with ischemic injury and apoptotic insult. The occurrence of hyaline globules in this case report could suggest that also in fish thanatosomes could be considered of some diagnostic and differential diagnostic importance in order to confirm these pathophysiologic conditions.