Background: Heteropneustes fossilis (Bloch, 1794) is one of the popular freshwater fish known for its food quality and nutritional value. This study was undertaken with an aim to find out histopathological changes in the intestine of freshwater fish Heteropneustes fossilis, host of trematode parasite Masenia vittatusia Agarwal, 1963. Methods: The intestine of uninfected fish used to determine normal anatomy, while infected intestine to determine pathological changes. The normal histological procedure was followed, which included fixing, rinsing, dehydrating and embedding of tissue. Tissue was cut in 4-6 µm thick sections using a rotary microtome. Haematoxylin and eosin stains were used. Result: The highest damage was observed in the mucosal layer with ruptured and fused microvilli, hyperplasia of villi, damaged columnar epithelium layer and spread of loose connective tissue into the lumen. Other degenerative modifications included hypertrophy of blood vessels in mucosa and muscularis part, some of them ruptured might be the cause of haemorrhage inside the layers. Other changes include variation in the routine shape of all three layers. The mucosal layer showed aggregation of lymphocytes and mast cells as well.

In recent years, the modified theory of gravity known as [Formula: see text] gravity has drawn interest as a potential alternative to general relativity. According to this theory, the gravitational force is determined by a function of the so-called “non-metricity” tensor [Formula: see text], which expresses how far a particle space-time is from the metric geometry. In contrast to general relativity, which describes the gravitational field using the curvature tensor, [Formula: see text] gravity builds a theory of gravity using the non-metricity tensor. For this class of theories, dynamical system analysis of the background and perturbation equations has been carried out in this work to determine how various models behave cosmologically. Here, the critical points are determined for two [Formula: see text] models from the literature: the power law, [Formula: see text], and the logarithmic, [Formula: see text] models. The stability behavior and corresponding cosmology are displayed for each critical point. For the power law model, we achieve a matter-dominated saddle point with the right matter perturbation growth rate. For the logarithmic model, we get a saddle point dominated by the geometric component of the [Formula: see text] model with perturbations in the decomposition of matter. For both models, we later achieved a stable and accelerating Universe with constant matter perturbations.