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Morphology Study of the Alimentary Tract of Fish

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A special issue of Animals (ISSN 2076-2615). This special issue belongs to the section "Aquatic Animals".

Deadline for manuscript submissions: closed (20 October 2022) | Viewed by 6915

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Special Issue Editor

Dr. Francesco Abbate

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Guest Editor

Department of Veterinary Sciences, University of Messina, Messina, Italy
Interests: fish; immunohistochemistry; light microscopy; scanning electron microscopy; tongue

Special Issue Information

Dear Colleagues,

The morphology of the alimentary tract of fish has been extensively studied in recent decades. Digestive and absorption functions are as important as osmoregulation, the secretion of hormones involved in metabolism and digestion, and immunity acting as a barrier to the external environment. Moreover, basic digestive functions, such as motility, secretion and absorption, are regulated by the concomitant activities of nerve inputs and chemical signals. The role of the nervous system in the alimentary tract is crucial, considering not only the inputs from the central nervous system, but also the large number of enteric nervous system neurons present in the digestive tract, forming the so-called 'mini brain'.

In more than 30000 fish species, the differences in fish anatomy are significant, and the diversity in the alimentary tract is more evident than in other organ systems, thus demonstrating an important impact on nutritional requirements. Feeding characteristics are, in fact, closely linked to the morphological and functional adaptations of the fish digestive system to the environment, thus explaining the numerous differences observed in all organs of the digestive system.

This Special Issue of Animals aims to collect different morphological investigations of the fish alimentary tract, including original and review articles of basic and applied approaches, using both classical and innovative techniques to contribute to the knowledge on fish anatomy.

Dr. Francesco Abbate
Guest Editor

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Keywords

Fish
Digestive system
Electron microscopy
Light microscopy
Immunohistochemistry
Molecular biology

Published Papers (3 papers)

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Research

8 pages, 2856 KiB

Open AccessArticle

Neurotrophins in Zebrafish Taste Buds

by Claudia Gatta, Valentina Schiano, Chiara Attanasio, Carla Lucini and Antonio Palladino

Animals 2022, 12(13), 1613; https://0-doi-org.brum.beds.ac.uk/10.3390/ani12131613 - 23 Jun 2022

Cited by 1 | Viewed by 1388

Abstract

The neurotrophin family is composed of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), Neurotrophin 3 (NT3) and NT4. These neurotrophins regulate several crucial functions through the activation of two types of transmembrane receptors, namely p75, which binds all neurotrophins with a similar affinity, and tyrosine kinase (Trk) receptors. Neurotrophins, besides their well-known pivotal role in the development and maintenance of the nervous system, also display the ability to regulate the development of taste buds in mammals. Therefore, the aim of this study is to investigate if NGF, BDNF, NT3 and NT4 are also present in the taste buds of zebrafish (Danio rerio), a powerful vertebrate model organism. Morphological analyses carried out on adult zebrafish showed the presence of neurotrophins in taste bud cells of the oropharyngeal cavity, also suggesting that BDNF positive cells are the prevalent cell population in the posterior part of the oropharyngeal region. In conclusion, by suggesting that all tested neurotrophins are present in zebrafish sensory cells, our results lead to the assumption that taste bud cells in this fish species contain the same homologous neurotrophins reported in mammals, further confirming the high impact of the zebrafish model in translational research. Full article

(This article belongs to the Special Issue Morphology Study of the Alimentary Tract of Fish)

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18 pages, 9237 KiB

Open AccessArticle

The Alimentary Tract of African Bony-Tongue, Heterotis niloticus (Cuvier, 1829): Morphology Study

by Maria Cristina Guerrera, Marialuisa Aragona, Marilena Briglia, Caterina Porcino, Kamel Mhalhel, Marzio Cometa, Francesco Abbate, Giuseppe Montalbano, Rosaria Laurà, Maria Levanti, Germana Germanà, Giacomo Zaccone, Krystyna Zuwala, Michal Kuciel and Antonino Germanà

Animals 2022, 12(12), 1565; https://0-doi-org.brum.beds.ac.uk/10.3390/ani12121565 - 17 Jun 2022

Cited by 5 | Viewed by 2356

Abstract

A morphological study of the alimentary tract, from the oropharyngeal cavity to the rectum, including the attached glands, of African bony-tongue, Heterotis niloticus (Cuvier, 1829) was carried out by gross anatomy, and light microscope analysis. This study aimed to give a deeper knowledge of the alimentary tract morphological features of this species of commercial interest. H. niloticus is distinguished by individual morphological characteristics showing a digestive tract similar to that of reptiles and birds. Within the oropharyngeal cavity, two tubular structures with digitiform ends are arranged on both lateral sides of the triangular tongue. The oropharyngeal cavity connects the stomach by a short esophagus. This latter is adapted to mechanical trituration, and it is divided into a pars glandularis and a thick-walled pars muscularis. The gizzard flows into the anterior intestine and two blind pyloric appendages, which exhibit specific functions, including immune defense for the presence of secondary lymphoid organs. The anterior intestine continues with the middle and posterior tracts up into the rectum. According to the histological observations, all regions of the alimentary tract have common structural features, typical of hollow organs, with differences in the mucosa structure that reflects the different functions of the apparatus, from mouth to anus. Within this study, we provided the first basis for future studies on optimizing rearing conditions, feed conversion ratio, and the digestive capacity, improving the growth performance of this species, and ensuring its conservation. Full article

(This article belongs to the Special Issue Morphology Study of the Alimentary Tract of Fish)

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21 pages, 34286 KiB

Open AccessArticle

Telocytes: Active Players in the Rainbow Trout (Oncorhynchus mykiss) Intestinal Stem-Cell Niche

by Nicole Verdile, Rolando Pasquariello, Gloriana Cardinaletti, Emilio Tibaldi, Tiziana A. L. Brevini and Fulvio Gandolfi

Animals 2022, 12(1), 74; https://0-doi-org.brum.beds.ac.uk/10.3390/ani12010074 - 30 Dec 2021

Cited by 4 | Viewed by 2204

Abstract

In order to improve the sustainability of trout farming, it is essential to develop alternatives to fish-based meals that prevent intestinal disorders and support growth performances. Therefore, an accurate knowledge of intestinal morphology and physiology is desirable. We previously described the epithelial component of the intestinal stem-cell (ISC) niche in rainbow trout (Oncorhynchus mykiss), which is one of the most successfully farmed species and a representative model of the salmonids family. This work aims to expand that knowledge by investigating the niche stromal components that contribute to intestinal homeostasis. We analyzed samples belonging to five individuals collected from a local commercial farm. Histological and ultrastructural studies revealed peculiar mesenchymal cells adjacent to the epithelium that generated an intricate mesh spanning from the folds’ base to their apex. Their voluminous nuclei, limited cytoplasm and long cytoplasmic projections characterized them as telocytes (TCs). TEM analysis showed the secretion of extracellular vesicles, suggesting their functional implication in cell-to-cell communication. Furthermore, we evaluated the localization of well-defined mouse TC markers (pdgfrα and foxl1) and their relationship with the epithelial component of the niche. TCs establish a direct connection with ISCs and provide short-range signaling, which also indicates their key role as the mesenchymal component of the stem-cell niche in this species. Interestingly, the TC distribution and gene-expression pattern in rainbow trout closely overlapped with those observed in mice, indicating that they have the same functions in both species. These results substantially improve our understanding of the mechanisms regulating intestinal homeostasis and will enable a more detailed evaluation of innovative feed effects. Full article

(This article belongs to the Special Issue Morphology Study of the Alimentary Tract of Fish)

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