Histology and ultrastructure of the pig parotid gland

Abstract

Parotid glands of adult pigs were studied by light and electron microscopy. The parenchyma consists of acini, intercalated ducts, striated ducts, and excretory ducts.Acini had little affinity for periodic acid-Schiff and were alcian blue-negative at pH 2.6 or 0.5. These results indicate a paucity of neutral mucins and an absence of sialo-and sulfomucins. Histologically, acinar cells had vacuoles which corresponded ultrastructurally to large electron-lucent secretory granules. The latter contained electron-dense bodies and lipid droplets. Acinar cells differed histochemically and ultrastructurally from typical serous cells and were classified as special serous.Intercalated duct cells near acini contained electron-dense secretory granules and numerous microfilaments. Cells in distal segments lacked secretory granules.Striated ducts were lined by two types of columnar epithelial cells, light cells and dark cells. Light cells were characterized by numerous infoldings of the basal plasma membrane, mitochondria between the infoldings, and electron-lucent vesicles in the apical cytoplasm. The mitochondria contained tubular cristae. Dark cells were characterized by an abundance of microfilaments and numerous infranuclear processes which extended to the basement membrane.Excretory ducts, in addition to light and dark cells, also contained basal cells and goblet cells. Mitochondria in the light cells had flattened rather than tubular cristae.The pig parotid is a unique salivary gland and the most atypical mammalian parotid gland studied thus far. Mitochondria with tubular cristae and vacuolated special serous cells with lipid in the secretory granules are hallmarks of the pig parotid. This paper reports the histochemistry and ultrastructure of an unusual parotid gland, that of the domestic pig (Sus scrofal. Acini of this gland were first classified histochemically as serous (Shackleford and Klapper, '621, but low amylase activity in the saliva (Chauncey et al., '63) and vacuolated acinar cells

Ultrastructure of submandibular salivary glands of mouse: TEM and HRSEM observations

“…Salivary samples are a type of organized tissue with an epithelium constituted by acinar and ductal cells (Cook et al,1994). Several authors using TEM have reported the ultrastructural characteristics of salivary glands of rats and mice (Hand,1972; Parks,1961; Scott and Pease,1959), squirrel monkey (Shackleford and Schneyer,1964), baboons (Tandler and Erlandson,1976), pigs (Boshell and Wilborn,1978), and humans (Riva and Riva‐Testa,1973; Riva et al,1976). On the other hand, using conventional scanning electron microscope (SEM), the structures of salivary glands were studied by Watanabe et al (1992a,1989); but using high resolution scanning electron microscope (HRSEM), there are few papers showing the intracellular components of submandibular and parotid glands which are reported in several animals (Watanabe et al,1992b,1994,1996,1997a,b,c,d).…”

Ultrastructural study of the adult albino rat parotid gland with special reference to the role of stromal telocytes

“…Ultrastructural studies of the parotid gland have been carried out in many different mammalian species including the spider monkey [13], pig [14], rabbit [15], human [16], rat [17], and goat [18]; common findings of these studies indicated that the parotid gland was composed almost exclusively of serous-secreting cells.…”

Effects of Isoproterenol on the Ultrastructure of Pig Parotid Gland

“…The ultrastructure of acinar cells in pigs was described by Ferrandi [1969], Boshell and Wilborn [1978] and Ginsbach and Kuhnel [1978] and will be reviewed briefly. Characteristically, acinar cells contained abundant electron-lucent secretory gran ules.…”

“…This paper reports on the effects of chronic administration of IPR on the parotid gland of another species, the domestic pig (Sus scrofa). The parotid gland of the pig strikingly contrasts with serous glands such as the rat parotid gland in that it is low in amylase [Chauncey et al, 1963] and the secretory granules are electron-lucent instead of electron-dense, thus giving the acinar cells a vacuolated appearance \Fer-randi, 1969;Boshell and Wilborn, 1978;Ginsbach and Kuhnel, 1978]. These findings resulted in the reclassification of the pig parotid gland as special serous [ Boshell and Wilborn, 1978].…”

“…The parotid gland of the pig strikingly contrasts with serous glands such as the rat parotid gland in that it is low in amylase [Chauncey et al, 1963] and the secretory granules are electron-lucent instead of electron-dense, thus giving the acinar cells a vacuolated appearance \Fer-randi, 1969;Boshell and Wilborn, 1978;Ginsbach and Kuhnel, 1978]. These findings resulted in the reclassification of the pig parotid gland as special serous [ Boshell and Wilborn, 1978]. Since the effects of IPR on special serous cells are little known, it was thought to be of interest to study the ultra structure of the pig parotid gland after chronic administration of IPR in order to clarify further the effects of IPR on salivary glands.…”