Comprehensive study of the digestive tract in the European hake (Merluccius merluccius)

Devčić, Lucija; Valić, Damir; Lovrić, Marin; Vlahek, Ivan; Benko, Valerija; Kužir, Snježana (2025) Comprehensive study of the digestive tract in the European hake (Merluccius merluccius). Slovenian Veterinary Research, 62 (1). pp. 37-48. ISSN 1580-4003

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Abstract

The European hake (Merluccius merluccius) is an important commercial fish that is widespread in the Adriatic Sea. It is a carnivorous fish whose diet consists mainly of fish. The aim of this study was to perform a detailed analysis of the digestive tract in the European hake. Therefore, the anatomy and histology of the posterior part of the digestive tract (from the esophagus to the rectum) were described. The fish were caught by longline fishing in the middle part of the Adriatic Sea along the Croatian coast. A total of 33 adult specimens were analyzed. Tissue components were visualized using hematoxylin-eosin, Mallory's trichrome, Verhoeff-Van Gieson, Alcian Blue-PAS kit and a reticular fiber staining kit. To investigate cellular digestion, the localization and activity of alkaline phosphatase, acid phosphatase, non-specific esterase and aminopeptidase were measured. All parts of the digestive tract were composed of mucosa, submucosa, muscularis and serosa. The type of epithelium varied from part to part. The muscular layer of the mucosa was not identified in the esophagus, the intestine proper and the rectum. The muscularis consisted of smooth muscle cells, except in the esophagus, where it consisted of striated muscle fibers. All parts of the digestive tract are involved in the digestion and absorption of nutrients. Results observed from optical density of enzymes highlighted that although the intestine was the main site for lipid and protein digestion, the stomach and rectum were also important locations for protein digestion. Although the anatomy and histology of the digestive tract in European hake have been partially described, there is no data on the optical density of the enzymes in the available literature. To achieve objective results that allow for precise data comparison, the optical density of the enzymes was measured in this study. This research provide comprehensive findings and introduced new knowledge that significantly expands and partly differs from what is known so far, highlighting the necessity for further studies in this area.

Item Type:	Article
Uncontrolled Keywords:	European hake; Merluccius merluccius; histology; histochemistry; digestion; enzymes
Subjects:	BIOMEDICINE AND HEALTHCARE > Veterinary Medicine > Basic and Preclinical Veterinary Sciences
Divisions:	Division for Marine and Enviromental Research
Depositing User:	Ema Buhin Šaler
Date Deposited:	26 Mar 2026 12:06
URI:	http://fulir.irb.hr/id/eprint/11495
DOI:	10.26873/svr-2093-2024

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