The effect of aging on the rat submandibular gland: An ultrastructural, cytochemical and biochemical study

Abstract

The effect of aging on the rat submandibular gland was studied by using ulIrastructural, ultrastructural cytochemical and biochemical techniques. There was an age-related clumping of the nucleolar-associated and peripheral chromatin in many of the acinar cells and a decrease in the number of cisternae of rough endoplasmic reticulum. Many aged acinar cells were binucleated. There was also an agc-related increase in pigment granules throughout the gland. These membrane bound granules consisted of a lipid droplet and an associated dense cap which had a granular matrix and pigment droplets. The lead capture method for acid phosphatase activity demonstrated that activity was associated with the granular matrix of the dense cap. These results were corrclated with the age-related increase in acid phosphatase activity as determined by colorimetric procedures.There was an age-related increase in thc number of cells characterized by small secretory gr,anules. These cells were found as part of the intercalated ducts or at the junction of the duct with the acini. Oncocytes were also found as par1 of the parenchyma of the aged submandibular gland. Thcse cells were charactcrized by the pleomorphic mitochondria that fill their cytoplasm. Occasionally, cells that possessed extraordinary numbers of mitochondria and small secretory granules were also observed.The determinations of total DNA and R N A revealed an age-related deaease in RNA while there was no significant change in the concentration of DNA.Several age-related changes have been reported to occur in the submandibular gland. One of these changes was the observation of "oncocytes" in the submandibular gland of man. Hamper1 ('3 1, '33) described these altered cpithelial cells as having an eosinophilic granular cytoplasm.Oncocytes (Andrew, '49) have also been reported in the submandibular gland of senile rats. However, these cells were described as aci nar cells that possessed a foamy reticulated cytoplasm, reduced cytoplasmic basophilia and either pycnotic or hypertrophic nuclei, with thc latter having a pronounced nucleolus. More recently, several studies of oncocytic tumors in man have described the ultrastructural morphology of the granular eosinophilic cells that were previously reported by Hamperl. The cytoplasm of these cells was packed with pleomorphic mitochondria (Tandler and Shipkey, '64; Balogh and Roth, '65; McGavran, '65).There appears to be some discrepancy in the reported description of oncocytes as they appear in the rat and human submandibular gland. This discrepancy led the author to examine the age-related changes that occur in thc ultrastructural morphology of the rat sub-J. MOKPH.. 130: 337-352. mandibular gland. It is also the purpose of this investigation to correlate these age-related alterations in morphology with age-related changes that occur in the cytochemistry and biochemistry of the rat submandibular gland. MATERIA1,S AND METHODSMale and female Wistar rats, 4 months, 9 months and 24 months of age were housed in wire mesh cages and ...

Changes in the secretory acinar cells of the rat parotid gland during aging

“…In parotid glands, lipofuscin granules are found only rarely in the acinar cells of 2-month-old rats, but increase in number with age. Similar granules are present also in submandibular glands of old rats (Bogart, 1970).…”

“…One of the most notable changes which occurs in these cells in relation to aging is the increase in the number of lipofuscin granules, as appears to be the case in rat submandibular glands (Bogart, 1970). Also, there are lipid droplets that tend to form aggregates at the base of the cells in old rats.…”

Fine Structure of the Mandibular Gland in Crest-tailed Marsupial-rat (<I>Dasyuroides byrnei</I>)

“…Therefore, the preacinar cells presently described are considered to differ from those in rats, Djungarian hamsters, rabbits and volcano rabbits. Qwarnstrom and Hand [15] and Bogart [3] described that such cells adjacent to acini or intercalated ducts in rats may constitute a mature secretory cell population or represent progenitor cells for acinar and intercalated duct cells or an aging phenomenon. The physiological significance and generation of these cells are unknown.…”

Fine Structure of the Mandibular Gland in Volcano Rabbit

“…As to the such cells adjacent to acinar or intercalated duct cells in the rat, Qwarnstrom and Hand [9], and Bogart [2] described that they might represent progenitor state of acinar and intercalated duct cells or aging phenomenon. Although the preacinar cells of the volcano rabbit mandibular gland were basically similar to the structures of acinar cells, they are thought to be differentated cell types, since their granules of the preacinar cells were unlike the granules of intercalated duct and acinar cells.…”