Histological structure of the digestive tract and digestive enzymatic activity of juvenile Pacific seahorse (Hippocampus ingens)

Abstract

The histological structure, histochemical features, and enzymatic activity of the digestive tract of juvenile Pacific seahorse (Hippocampus ingens) are described to provide information during the cultivation of this species. Serial histological sections were stained with either hematoxylin-eosin, alcian blue-PAS, toluidine blue, Sudan black, Masson's trichome, and ninhydrin-Schiff to describe the general features and the presence of glycogen, mucopolysaccharides, lipids, muscle layers, and proteins, respectively. The enterocytes height and the mucosal villi height in the esophagus and intestines were measured. Additionally, the digestive enzymes trypsin, chymotrypsin, lipase, amylase, aminopeptidase, acid phosphatase, and alkaline phosphatase activities were recorded. The esophagus showed two distinctive regions, the anterior with numerous mucous cells secreting acid mucins and the posterior with longitudinal folds and no mucous cells. The intestine was differentiated into three regions. The anterior showed goblet cells secreting acid and neutral mucins, while the middle and posterior regions presented goblet cells secreting only acid mucins. The activity of aminopeptidase, chymotrypsin, and amylase showed low levels, while the trypsin and acid phosphatase activity levels were intermediate. Lipase and alkaline phosphatase showed the highest activities. The results point that juvenile H. ingens presents a digestive structure similar to other teleost species. The high levels of lipase suggest that juvenile H. ingens have high requirements for lipids during this stage.

Local Ecological Knowledge and Use of the Pacific Seahorse (Hippocampus ingens) by Residents of the State of Sinaloa, Mexico

“…Respondents gave no information regarding the survival rate of newborns. It has been reported that seahorses do not have a larval phase and are born as miniature adults that only grow in size and modify their external morphology according to habitat conditions and feeding (Corona-Rojas et al 2021; Encomendero et al 2011).…”

Análisis morfológico y morfométrico de Hippocampus ingens Girard, 1858 “caballito de mar” en estado de deshidratación

“…Hippocampus ingens "caballito de mar", es un pez que presenta muchas características estructurales que son adaptaciones para su estilo de vida acuática, además los conteos y mediciones destacan la necesidad de buscar características morfológicas que avalen las diferencias establecidas y pueden ayudar a diferenciar la especie de Hippocampus endémica y característica de nuestro litoral (Corona-Rojas, 2015;Corona-Rojas et al, 2021).…”