Histological development of the digestive system of Mayan cichlid Cichlasoma urophthalmus (Günther 1862)

Abstract

Summary The ontogeny of the digestive tract in Cichlasoma urophthalmus was studied by means of optical microscopy from hatching to 30 days post‐hatching (dph; 855 degree days, dd). The development of the digestive system in this precocial species was a very intense and asynchronous process, which proceeded from both distal ends interiorly. At hatching, the digestive tract consisted of a straight tube with a smooth lumen dorsally attached to the yolk‐sac. The digestive accessory glands were already differentiated and eosinophilic zymogen granules were visible in the exocrine pancreas. At the onset of exogenous feeding between 5 and 6 dph (142.5–171.0 cumulative thermal units, CTU), the buccopharynx, oesophagus, intestine, liver and pancreas were almost completely differentiated, with the exception of the gastric stomach that completed its differentiation between 11 and 14 dph (313.5–399.0 CTU). The development of gastric glands at 14 dph and the differentiation of the stomach in the fundic, cardiac and pyloric regions at 19 dph (541.5 CTU) were the last major events in digestive tract development and designated the onset of the juvenile period. Remnants of yolk were still detected until 16 dph (456.0 CTU), indicating a long period of mixed nutrition that lasted between 10 and 11 days (285.0–313.5 CTU). The results of the organogenesis of larvae complement previous data on the functionality of the digestive system and represent a useful tool for establishing the functional systemic capabilities and physiological requirements of larvae to ensure optimal welfare and growth under aquaculture conditions, which might be useful for improving current larval rearing practices for this cichlid species.

Development of the digestive tract in first feeding larvae ofBetta splendensRegan, 1910

“…According to Sarasquete, Gisbert, Ribeiro, Vieira, and Dinis (2001), these cells are involved in the lubrication of mucosa and in the protection against physical and/or chemical harm caused by the ingestion of prey, and even against bacterial infection. Similarly to most studies, the present work classified mucus-secreting cells as goblet or mucosecretory cells irrespective of their location, as described by Cuenca-Soria et al (2013). Nevertheless, some studies have differentiated these two types of cells: the former being found in the oesophagus and with a saccular shape, the latter in the intestine, as described by Leknes (2011) for Hyphessobrycon anisitsi.…”

“…Taste buds appeared in the buccopharyngeal cavity at 32 hph. The presence of taste buds has also been reported on and in the oral cavity of Tor tambroides at 4 days post‐hatching (Ramezani‐Fard et al., ) and of Cichlasoma urophthalmus at 3 dph (Cuenca‐Soria et al., ). This tasting ability in the buccopharyngeal cavity enables the fish to decide whether to swallow or reject a food item that has been apprehended (Kasumyan, ).…”

“…Similarly to most studies, the present work classified mucus‐secreting cells as goblet or mucosecretory cells irrespective of their location, as described by Cuenca‐Soria et al. (). Nevertheless, some studies have differentiated these two types of cells: the former being found in the oesophagus and with a saccular shape, the latter in the intestine, as described by Leknes () for Hyphessobrycon anisitsi .…”

“…of Cichlasoma urophthalmus at 3 dph (Cuenca-Soria et al, 2013). This tasting ability in the buccopharyngeal cavity enables the fish to decide whether to swallow or reject a food item that has been apprehended (Kasumyan, 1999).…”

Ontogeny of the digestive tract in mud loachMisgurnus anguillicaudatuslarvae

“…However, the ontogeny of the digestive system of loach larvae and the development of intestinal dual functions have never been reported. Knowledge regarding the morphological and functional changes during early ontogeny in fish is of great importance in order to adapt rearing technology according to the digestive ability of fish larvae (Pradhan, Jena, Mitra, Sood & Gisbert ; Cuenca‐Soria, Alvarez‐Gonzalez, Ortiz‐Galindo, Tovar‐Ramirez, Guerrero‐Zarate, Aguilar‐Hernandez, Perera‐Garcia, Hernandez‐Gomez & Gisbert ). The objective of this study was to understand the ontogeny of the digestive system of loach from hatching to 45 days after hatching (DAH), aiming to discover not only the sequence of the structural and functional development of the digestive organ but also the development of the intestine as an air‐breathing organ.…”