Identification of the Paneth cells in chicken small intestine
L. Wang,1 J. Li,1 J. Li Jr., R. X. Li, C. F. Lv, S. Li, Y. L. Mi, and C. Q. Zhang2
Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, P.R. China
ABSTRACT The Paneth cells are highly specialized cells at the base of the crypts in the chicken small in- cells in the epithelium of the small intestine of many testine. Western blotting experiment also manifested vertebrate species. These cells reside at the base of the expression of lysozyme protein, which is specifi- crypts of the Lieberk¨uhn and contain abundant se- cally secreted by the Paneth cells in the small intestine. cretory granules. Previous studies suggesting the ex- Moreover, lysozyme c and lysozyme g mRNAs were ex- istence of Paneth cells in the chicken (Gallus gallus) pressed in the small intestine of chickens at different remained controversial. Here we seek to identify the ages. Lysozyme c mRNA, in particular, was located at Paneth cells in the chicken small intestine through mor- the base of the small intestinal crypts as displayed by phological examination and specific gene expression. in situ hybridization. Collectively, we provide evidences Histological staining and transmission electron micro- that the Paneth cells indeed exist in the small intestine scope confirmed the presence of granulated secretory of the chicken. Key words: paneth cell, chicken, crypt, lysozyme 2016 Poultry Science 95:1631–1635 http://dx.doi.org/10.3382/ps/pew079
INTRODUCTION released from the Paneth cells protect the host from enteric pathogens (van Es and Clevers, 2014). In addi- In mammals, the Paneth cells play important im- tion, the secretions of the Paneth cells constitute the mune defense roles in the intestines, particularly relat- niche for Lgr5 stem cells in the intestinal crypts (Sato ing to intestinal epithelium renewal and early stages et al., 2011). The Paneth cell can also act as the site of intestinal inflammation. The Paneth cells are re- of origin for intestinal inflammation (Adolph et al., stricted to the crypts of the small intestine, along 2013). with goblet cells, enterocytes, tuft cells, and en- In previous studies, by immunostaining with teroendocrine cells. These cells represent the princi- lysozymes (Erlandsen et al., 1974), defensins (Cun- pal cell types of the epithelium of the small intes- liffe et al., 2001), and with secretory phospholipase A2 tine (van Es and Clevers, 2014). The Paneth cells (Nevalainen et al., 1995), a wide variety of species in- were first described by J. Paneth in 1888 as granu- cluding primates, rodents and horse have been demon- lated cytoplasmic cells located at the base of small in- strated to be abundantly populated with the Paneth testinal crypts, the “crypts of Lieberk¨uhn”. Classical cells. Conversely, the absence of the Paneth cell in other Paneth cells are pyramidal shaped secretory cells with species’ intestines, including those of the cow, sheep, basally situated nuclei, extensive endoplasmic retic- ostrich, sloth, seal, crocodile, and colubrid snake, has ulum and Golgi network, and prominent, large api- also been noted. For some other species, including do- cal granules that occupy most of their cytoplasm. mestic cats and the dogs, the presence of the Paneth The large secretory granules in the Paneth cells are cell remains controversial and unconfirmed (Porter et rich in antimicrobial peptides (such as lysozyme, α- al., 2002). Whether the Paneth cells are present in the defensins/cryptdins, and secretory phospholipase A2), avian gastrointestinal tract was debatable. Humphrey immune modulators (such as IgA), and trophic fac- and Turk (1974) reported the presence of the Paneth tors (such as carboxylic ester hydrolase) (Porter cells in the crypts of the chick intestine epithelium et al., 2002; Elphick and Mahida, 2005; Ouellette, by using low-power light microscopy (Humphrey and 2010; Bevins and Salzman, 2011; Clevers and Bevins, Turk, 1974). However, there is still doubt about the 2013). Antimicrobial peptides or immune modulators existence of the Paneth cells in the chicken small in- testine, based on the observation that the continu-