A Study on Structural Characteristics of Intestinal Tract of the Air-Breathing Loach, Paramisgurnus dabryanus (Sauvage, 1878)
A Study on Structural Characteristics of Intestinal Tract of the Air-Breathing Loach, Paramisgurnus dabryanus (Sauvage, 1878)
YaQiu Liu and ZhiJian Wang*
ABSTRACT
This study aimed to observe morphology and ultrastructure of intestinal tract of Paramisgurnus dabryanus with light and electron microscopies. Intestinal tract was divided into three parts. Morphologically complex folds were formed on surfaces of anterior and middle intestines where many secretory cells were present. Highly developed junction complex were seen in anterior intestine. Cytoplasm contained abundant mitochondria and pinocytotic vesicles. Epithelium of posterior intestine was thin, translucent and squamous with dense blood capillary network underground, while there were no folds on mucous membrane surface. Distance between blood capillary network and intestinal cavity was 1.95±0.34 μm. Respiration epithelial cells of posterior intestine are a kind of modified squamous epithelial cells which show the ultrastructural characteristics of both types I and II pneumocyte of lung alveoli in mammals. The blood is composed of three layers: the thin layer of the extended cytoplasm of respiratory epithelial cells (1.47±0.23 μm), the thin sheet of cytoplasm of endothelial cells (0.21±0.03 μm) and the basement membrance (0.27±0.05 μm) between them is similar to that of the respiratory organs in other vertebrates.Intestinal tract has digestion and respiration functions. Anterior intestine performs digestion/absorption. Posterior intestine performs gas exchange/accessory respiration. In middle intestine, digestion and respiration overlap.
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August 2017
Vol. 49, Iss. 4, Pages 1151-1546
