Tissue and Cell 43 (2011) 190–195 Contents lists available at ScienceDirect Tissue and Cell journal homepage: www.elsevier.com/locate/tice Histochemical features of the Muscovy duck small intestine during development Bao An Ding a , Andrea Pirone b,∗ , Carla Lenzi b , Nie Xiaoming a , Alessandro Baglini b , Isabella Romboli b a Department of Animal Science, Qing Hai University, 810016 Xining, China b Department of Animal Production, University of Pisa, 56124 Pisa, Italy article info Article history: Received 15 November 2010 Received in revised form 1 March 2011 Accepted 1 March 2011 Available online 5 April 2011 Keywords: Muscovy duck Development Intestine Argyrophil cells Goblet cells abstract We demonstrated for the first time the distribution and morphology of argyrophil and of goblet cells in the mucosa of the small intestine of the Muscovy duck during development using the Grimelius silver staining and alcian blue/periodic acid-Schiff (AB/PAS) staining technique. The argyrophil cells distribution was variable over the length of the small intestine from embryonic day 24 (24E) to post-hatching day 13 (13d). In the villi most argyrophil cells belonged to the open-type, while in the crypts they belonged to the closed-type. In the duodenum the density of argyrophil cells was highest at hatching, while in the jejunum and in the ileum the highest density value was at hatching and 13d. AB/PAS-positive goblet cells appeared on the villi and crypts of the duodenum and jejunum at 30E, and in the ileum at hatching. The density of AB/PAS-positive cells was the highest in the three segments at hatching. The AB-positive cells, compared with the PAS-positive cells, predominated in villi and crypts of the three segments, moreover the rate of AB-positive cells to PAS-positive cells significantly decreased from 30E to 9d. An increase in argyrophil and goblet cells number during the later incubation and at hatching, could indicate the small intestine in that period is being prepared to face a new diet. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction The gastrointestinal tract is the largest endocrine organ of the body. Endocrine cells are scattered among the epithelium cells of the gastrointestinal tract (Feyrter, 1938; Sundler and Hikanson, 1988). The digestive function is affected by hormones produced in many endocrine glands, but the most profound control is exerted by hormones produced within the gastrointestinal tract (Deveney and Way, 1983). Silver techniques have been regarded as a gen- eral method for detecting intestinal endocrine cells, in particular Grimelius positive stained cells are classified as argyrophil cells (Grimelius, 1968; Grimelius and Wilander, 1980). Argyrophil cells of the digestive tract are endocrine cells belonging to the amine precursor uptake and decarboxylation (APUD) system. The regional distribution and the relative frequency of these cells in the intes- tine have been found to vary with the animal class, such as fish (Pan et al., 2000), reptiles (Ku et al., 2001), birds (Rawdon and Andrew, 1981; Nascimento et al., 2007; Wang et al., 2010) and mammals (Ku et al., 2004a,b). In the gastrointestinal tract, argy- rophil cells were classified in two types according to the shape. The open-type cells, which have a triangular or elongated shape with an apical cytoplasmic process in contact with the glan- ∗ Corresponding author. E-mail address: apirone@vet.unipi.it (A. Pirone). dular lumen, and the closed-type cells, which are round, oval or conical-shaped without a luminal connection (Wang et al., 2010). Goblet cells are glandular simple columnar epithelial cells whose function is to secrete mucin, which dissolves in water to form mucus which covers the epithelial surface of the small intestine. Mucus acts both as a protective barrier against harmful intralumimal components (Smirnov et al., 2005) and as a medium for microorganisms; moreover it influences transport between luminal contents and the brush border (Forstner et al., 1995). Sev- eral studies have been carried out regarding the distribution of mucins in the intestine of many species (Hopwood et al., 1977, 1986; Jamdar and Ema, 1982; Henk et al., 1986; Long and Orlando, 1999; Poorkhalkali et al., 1999). Mucins, secreted by goblet cells, are classified into neutral and acidic subtype. The neutral mucins present in the gastric mucosa are the predominant mucin subtype while the acidic mucins are found in the intestinal epithelium, dom- inating in the large intestine (Sheahan and Jervis, 1976; Deplancke and Gaskins, 2001). Even though there are many studies which show the distribution of endocrine cells and mucin in the gastrointestinal tract of animals, most of them are focused on the adult animal. There has been little reported on the distribution of endocrine cells and goblet cells in the small intestine of Muscovy ducklings during development. In this study, we aimed to describe the changes in the endocrine cells and goblet cells in the duodenum, jejunum and ileum of the Muscovy duck during development. 0040-8166/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.tice.2011.03.001