Microscopic and ultrastructural study of the lymphatic system in the human parotid gland

The localization and fine structure of the lymphatic system vessels are examined in the human parotid gland. A network of lymphatic capillaries extends in the intralobular connective septa around the striated ducts. These lymphatics converge in collectors frequently bordering the excretory ducts. On the contrary, no lymphatics are present next to the intercalated ducts and adhenomers. Ultrastructurally, the lymphatic capillaries are characterized by a very thin endothelial wall and by slightly complicated intercellular adhesions. Open junctions are also present. The presence of numerous lymphatic capillaries bordering the striated ducts and their blood microvasculature is discussed in relation to the functional activities of the striated ducts in the modification of the saliva.     

Postnatal growth of the rat palatine gland

To elucidate how the palatine glands grow postnatally, the palatine glands of rats from 0 to 8 weeks of age were investigated histologically and immunohistochemically. Under light microscope, three dimensions of the right part of the palatine glands were measured and the total number of excretory ducts of the glands was counted from the parasagittal serial sections. Immunohistochemistry with anti-5-bromo-2'-deoxyuridine (BrdU) monoclonal antibody was also employed to detect the cellular proliferative activity. At birth (0 weeks), the palatine glands consisted of ducts and immature acini. The ducts in the glands were connected with excretory ducts. After 2 weeks, there was no duct in the glands. Most acinar cells became mature as mucous cells and took the form of tubulo-acini connected directly with excretory ducts. In the posterior region of the glands, serous acinar cells forming demilunes were occasionally seen. All three dimensions of the palatine glands became longer, and the number of excretory ducts tended to increase. Immunohistochemistry showed acinar and duct cells were highly proliferative in early stage of postnatal life and their proliferative activity decreased thereafter. This study demonstrated that immature rat palatine glands of newborn rats grow three-dimensionally during maturation, and that the parenchymal cell proliferation contributes to the growth of the rat palatine glands. In addition, it is suggested that the glandular tissue arises from the excretory ducts formed postnatally.     

A review of protonephridial excretory systems in Acanthocephala

Our present understanding of the excretory system of Acanthocephala is largely the result of work done by 5 German scholars: Kaiser, Schepotieff, Meyer, Kilian, and von Haffner. Present studies indicate that a protonephridial system is restricted to the family Oligacanthorhynchidae. However, many members of this family have not had a protonephridial system described. Three nephridial designs have been described: 1) dendritic type, organized as branches of a tree where each final branch terminates in a ciliated bulb; 2) capsular type, in which all ciliated bulbs empty directly into a common chamber; and 3) rudimentary type, consisting of a single cell with a patent ciliary pouch but no ducts to the outside. The first 2 types are a syncytia with 3 nuclei located in the capsule or stem wall and none in the flame bulbs. These excretory systems consist of 2 clusters of flame bulbs that empty separately into an expandable excretory bladder which in turn empties into ducts of the reproductive system. This urogenital system empties to the outside through a gonopore located at the tip of the penis in males and the posterior terminus of the vagina in females. Cilia occur in certain excretory tubes, depending on sex and species, but are unknown in the excretory bladder or ducts leading into it. The rudimentary type consists of a cell whose posterior extension terminates near the bursal lumen, but it is not known if this is significant for the discharge of material. There is no information on the physiology or biochemistry of the excretory system or its products.     

Glycoprotein secretion in the mouse submandibular gland as revealed by radioautography after L-3H-fucose injection

Summary Glycoprotein secretion in the mouse submandibular gland was investigated by light microscope radioautography of semi-thin sections after the administration of L-³H-fucose. The incorporation of the precursor in the acini was negligible. ³H-fucose was taken up in the paranuclear region of the cells lining the intercalated, secretory, striated and excretory ducts. This labeling pattern was interpreted as addition of the precursor to glycoproteins within the Golgi apparatus. Incorporation in the intercalated duct was restricted to the cells with fine cytoplasmic granules. The glycoproteins synthesized by the intercalated and secretory ducts were transported to the saliva by the secretion granules. It is assumed that the glycoproteins synthesized in the striated and excretory ducts are plasma membrane glycoproteins which seem to renew continuously. Quantitation of the radioautographs supplied data concerning the incorporation of ³H-fucose into newly synthesized glycoproteins as well as the renewal of the labeled macromolecules in each duct.     

An immunohistochemical study of secretagogue-induced secretion of epidermal growth factor in the submandibular salivary glands of mice

Routine histological and indirect immunofluorescence techniques were used to examine the histological details of changes in the distribution of epidermal growth factor (EGF) in the submandibular salivary glands of mice during secretion. Comparisons were made bewteen glands of normal mice and those of mice given one of a number of secretagogues at various times prior to sampling. Normal submandibular salivary glands in male mice had an extensive system of convoluted granular tubules (CGT), the cells of which contained EGF. When adrenaline of alpha-phenylephrine was administered, the CGT cells degranulated, and there was a concomitant loss of intracellular EGF-positive immunofluorescence. The excretory ducts were engorged with immunofluorescent material, indicating secretion of EGF into saliva, while the ductal cells themselves remained EGF-negative. The degranulation response could be blocked by phentolamine, but not by propranolol, and no changes in EGF distribution followed the administration of pilocarpine. It was concluded that EGF is secreted, at least partly into the saliva, following an alpha-adrenergic response, and that this occurs with degranulation of the cells of the CGT.     

Development of the cloaca and its ulterior transformations in the polypterids (Pisces)]

Generally spoken cloacae have been but little studied. In Polypterus, a brachiopterygian fish, a cloaca only exists during parts of the embryonal and larval life and it gets replaced by structures consisting of an anus and an urinary sinus. In the beginning of embryonal life the posterior opening of the body seems to be nothing else than the original blastoporus. The wall of this opening acquires evaginations; the anlagen of the excretory ducts come in contact with them, establishing in that way a structure, that merits the name of cloaca. During the elongation of the post-vitellin body, the latter gets shifted from the level of metamere XII to that of metamere XXX. Another migration of the cloaca occurs when the digestive system acquires its development. Finally the cloaca may be found under the 47th and 48th muscular segments (at least in the species Polypterus senegalus senegalus Cuvier). During these stages the excretory ducts have build up an urinary sinus that gets separated from the gut. In adults no communication exists any more between the gut and the urinary sinus; the latter is a very destinct organ that may have an impair or pair aspect according to its being filled up. Because of the establishing of a communication with the genital ducts the sinus becomes an uro-genital sinus in the adult.     

Comparative anatomy of excretory organs in vestimentiferan tube worms (Pogonophora, Obturata)

In the past, the excretory systems of only few vestimentiferan species have been examined in detail. This study presents comparative data on eight species on the basis of histological serial sections. Ridgeia piscesae was studied by transmission electron microscopy. All species examined possess a central excretory organ consisting of numerous small branching and intertwined excretory tubules. These are connected to voluminous glandular excretory ducts that lead to the exterior by single or paired excretory pores located at the anterior end of the vestimentum. A comparative analysis shows differences among the species with regard to several features, such as the number of excretory pores, presence/absence of excretory grooves and papillae, position of the excretory organ relative to the brain, and the shape of the excretory ducts. Neither podocytes nor coelomoducts could be detected; therefore, there is no indication of the presence of metanephridia. The vestimentiferan excretory system shows some similarities with the design in Athecanephria (Pogonophora, Perviata) and a general resemblance to the design in sabellid polychaetes, even though in the latter metanephridia are clearly present.     

Distinct immunohistochemical expression of osteopontin in the adult rat major salivary glands

Osteopontin is a multifunctional protein secreted by epithelial cells of various tissues. Its expression in the adult rat major salivary glands has not yet been studied. We examined osteopontin expression by immunohistochemistry using a well characterized monoclonal antibody. Submandibular glands of young adult male rats (70–100 days old) showed specific expression in secretion granules of granular duct cells but also in cells of the striated ducts and excretory duct. In the major sublingual as well as the parotid gland expression was found solely in the duct system. In addition, a few interstitial-like cells exhibiting very strong immunostaining for osteopontin could be found in either organ. Expression could neither be seen in acinar cells nor in cells of the intercalated ducts. Moreover, in submandibular glands of more aged rats (6- to 7-month old) which show well developed granular convoluted tubules, there was almost exclusive expression of osteopontin in granular duct cells as well as in some interstitial-like cells, but barely in the striated/excretory duct system. Western blot analysis of the submandibular gland showed a specific band migrating at approximately 74 kDa, detectable at both age stages. Osteopontin secreted fom granular duct cells may influence the compostion of the saliva, e.g. thereby modulating pathways affecting sialolithiasis. Its expression in striated duct cells may also hint to roles such as cell–cell attachment or cell differentiation. The cell-specific expression detected in the rat major salivary glands differs in part from that reported in mice, human and monkey.Nicholas Obermüller and Nikolaus Gassler contributed equally to this work.     

Intrinsic glands of the human esophagus

The esophagial glands obtained from 156 corpses of mature persons have been investigated by means of histological and histochemical methods. The glands studied are situated in the tela submucosa of the organ and, according to a number of structiral peculiarities and histological properties, they differ essentially from the salivary glands of the oral cavity. The glands are presented as large packets and have mucous, serous and mixed (seromucous and mucoserous) terminal parts. Their secret contains neutral glycoproteins, sialo- and sulfoglycoproteins and gets into the intercalary and further into the striated ducts which fuse and form a long common excretory duct; it opens at an acute angle into the esophageal cavity. There are single cells in the glands which possess secretory properties not connected with the excretory ducts of the gland. Their role in the organ is not yet clear.     

Identification of the taste cell G-protein, α-gustducin, in brush cells of the rat pancreatic duct system

 The major pancreatic excretory ducts have been shown to contain a large number of specialized epithelial cells, named brush cells, that are characterized by an apical tuft of stiff microvilli. The function of pancreatic brush cells is unknown. Because of some structural similarities to taste receptor cells of the tongue, we addressed the question whether pancreatic brush cells contain the taste cell-specific GTP-binding protein, α-gustducin, and hence might be considered to be involved in intraductal chemoreception. By immunostaining, we show that ductal brush cells of the rat pancreatic duct system contain α-gustducin, which is concentrated in the apical tuft of microvilli and is also found along the basolateral cell surface. A further outcome of this study is that brush cells are concentrated in the terminal portions of extralobular ducts and in the major pancreatic duct where brush cells comprise up to 22% of the ductal epithelium. Immunoblotting of the major pancreatic duct revealed a 42-kDa band that comigrated with α-gustducin of the rat tongue. In view of our previous observation that the ductal brush cells are particularly rich in nitric oxide synthase-I, there is reason to assume that these cells might play a role in certain aspects of chemoreceptive signalling. Thus, chemosensory control of pancreatic secretion might occur at two independent sites, the intestine and the terminal portions of the excretory duct system. Accepted: 2 March 1998     

Comparative histochemical observations on the excretory system of helminth parasites.

The excretory canals of Ascaridia galli (Nematoda) and the protonephridial ducts of Cotylophoron cotylophorum (Trematoda) and Raillietina cesticillus (Cestoda) have been studied with regard to the histochemical localization of lipids, carbohydrates and hydrolytic enzymes. Distinct excretory organs are absent in the acanthocephalan Centrorhynchus corvi. Triglycerides, phospholipids and lipoproteins are seen in association with the wall of excretory canals of A. galli and R. cesticillus, and phospholipids and lipoproteins at the corresponding site in C. cotylophorum. The physiological significance of lipids in association with excretion of substances has been discussed. Low molecular weight glycogen is present in the lumen of excretory canal of A. galli but not in other worms. The common feature of the excretory canals is the presence of enzyme activities of nonspecific alkaline phosphatase and Mg2+-dependent ATPase. Activity of acid phosphatase is seen only in the excretory canals of A. galli. Glucose-6-phosphatase is present in A. galli and C. cotylophorum and absent in R. cesticillus. Weak reaction of 5'-nucleotidase is present in the excretory canals of helminth species studied here. The role of these enzymes in transportation of substances across the wall of excretory canals and also in ionic regulation has been discussed in detail.     

Fasciola hepatica: attempts to induce protection against infection in rats and mice by injection of excretory/secretory products of immature worms

In vitro excretory/secretory products of 4-week (immature) and 8-week-old (mature) Fasciola hepatica parasites, derived from rats, were injected together with adjuvant into naive rats and mice. Resistance to infection was assessed in rats by counting adults in the bile ducts at 9 weeks, or in mice by recording deaths after oral challenge with a high dose of viable metacercariae. Exposure of rats to excretory/secretory products of immature F. hepatica conferred a significant degree of resistance which was comparable to the level of resistance induced following oral administration of a low number of metacercariae. No protection against infection was seen in rats injected with excretory/secretory products from mature, bile duct-derived worms. In mice, no obvious mouse strain variation in susceptibility to first infection existed and hypothymic nude mice were as susceptible to infection as intact mice. As determined by protection against death, vaccination with excretory/secretory products derived from immature F. hepatica was without effect in mice. It is concluded that "host protective antigens", at least for rats, were present in the excretory/secretory products of immature F. hepatica larvae.     

The ultrastructure of the duct system in the rat extraorbital lacrimal gland

Summary The duct system of the rat exorbital lacrimal gland consists of intercalated ducts, interlobular ducts and excretory ducts. The morphological changes from one type of duct to the next are gradual. At the light microscopical level this consists of a change from a bilaminar epithelium in the intercalated ducts to an epithelium, consisting of approximately three layers — which may be pseudostratified — in the excretory ducts. The basal layer of the intercalated ducts consists of myoepithelial cells, whereas the inner epithelial cells may have both a secretory and an electrolyte transporting function. The interlobular duct epithelium contains many cells with deep infoldings of the basolateral plasma membranes and associated mitochondria, suggesting a similar function to the striated duct epithelium in salivary glands. Numerous basal cells in this epithelium have tentatively been interpreted as unusual myoepithelial cells. Nerve terminals have been observed in the ductal epithelium.This work was supported by the National Health and Medical Research Council of Australia. — We wish to thank Mrs. Eva Vasak for her expert technical assistance.     

Development and Structure of Primary Secretory Ducts in the Stem of Commiphora wightii (Burseraceae)

Development of gum-resin ducts, sites of resin synthesis inthe epithelial cells and elimination of resin from the protoplasthave been studied in the stem of Commiphora wightii. Formationof an intercellular space amongst a group of densely stainedprocambial cells signals the initiation of a duct. It widensby anticlinal divisions of the epithelial cells and also bytheir further separation along the radial walls. The numerousplastids with varying morphological shapes have an electrondense matrix. Starch granules present in the amyloplasts showevidences of exocorrosion. Mitochondria in the epithelial cellsof developing and mature ducts have well developed, swollencristae. Osmiophilic material originates in association withthe golgi-derived vesicles at its maturing face. It is alsoobserved in close association with plastids, mitochondria andvacuoles, thereby plausibly involving them in the process ofresin formation. The resinous material is eliminated from thecytoplasm by vesicles enveloped by plasmalemma prior to theirdischarge into the apoplast. Myelin-like multilamellate structuresobserved along the inner tangential wall may aid in the secretionof resin across the wall. Commiphora wightii, primary secretory ducts, epithelial cells, ultrastructure, gum-resin secretion     

Sublingual structures in primates. Part 1: Prosimiae, Platyrrhini and Cercopithecinae

1. The sublingual structures of primates have been studied light-microscopically. There are 3 different sublingual structures in the species studied. The plica sublingualis occurs in all primates. The sublingual organ is a topographically modified plica sublingualis which occurs exclusively in Callicebus. A sublingua is present only in the prosimians. 2. The plica sublingualis contains the excretory ducts of the submandibular and sublingual salivary glands. The sublingua is ventrally adherent to the body of the tongue and is, with a few exceptions in Tupaia, characterized by a skeleton of cartilage tissue. A sublingua never exhibits excretory ducts or salivary glands. 3. In some Platyrrhini (Ateles, Aotus, Lagothrix, Alouatta, Callicebus), there are taste buds in the epithelium of the plica sublingualis. They are especially concentrated near the orifices of the salivary glands. 4. The fresh saliva of the submandibular and sublingual gland can be tested by the taste buds on the plica sublingualis, because there is a topographical coincidence. 5. There is a complete absence of taste buds at the plica sublingualis of the prosimians and the Cercopithecinae. 6. There are no taste buds in the epithelium of the sublingua. In the Lorisiformes and in the Lemuriformes the sublingua is a cleaning device of the anterior dentition, most probably in connection with a tactile sensibility. In the Tupaiformes and in the Tarsiiformes the sublingua is less developed. 7. There is no anatomical connection between the skeleton of cartilage tissue in the sublingua and the lytta, or the skeleton of the hyoideum. 8. In some Cercopithecinae (Macaca, Papio) a glandula apicis linguae is present.     

The effects of drugs, ions, and poly-l-lysine on the excretory system of Schistosoma mansoni

We have been able to label the excretory system of cercariae and all forms of schistosomula, immature and adult worms with the highly fluorescent dye resorufin. We have shown that the accumulation of the resorufin into the excretory tubules and collecting ducts of the male adult worm depends on the presence of extracellular calcium and phosphate ions. In the adult male worms, praziquantel (PZQ) prevents this accumulation in RPMI medium and disperses resorufin from tubules which have been prelabelled. Female worms and all other developmental stages are much less affected either by the presence of calcium and phosphate ions, or the disruption caused by PZQ. The male can inhibit the excretory system in paired female. Fluorescent PZQ localises in the posterior gut (intestine) region of the male adult worm, but not in the excretory system, except for the anionic carboxy fluorescein derivative of PZQ, which may be excreted by this route. All stages of the parasite can recover from damage by PZQ treatment in vitro. The excretory system is highly sensitive to damage to the surface membrane and may be involved in vesicle movement and damage repair processes. In vivo the adult parasite does not recover from PZQ treatment, but what is inhibiting recovery is unknown, but likely to be related to immune effector molecules.     

Biochemical and histochemical studies on non-specific phosphomonoesterases of swine kidney worm Stephanurus dentatus (Diesing, 1839).

Biochemical and histochemical studies have been made on non-specific acid and alkaline phosphomonoesterases of S. dentatus. The two forms of acid phosphomonoesterases have been found active at pH 4.0 and 6.0. The pH optima for the two forms of aklaline phosphomonoesterases lie at 8.0 and 10.0. Studies on the distribution of acid and alkaline phosphomonoesterases in various tissues have revealed an abundance of acid phosphomonoesterase in various parts of the alimentary canal and various organs of the reproductive system. The excretory ducts show alkaline phosphomonoesterase activity only.     

Structuro-functional units of the salivary and lacrimal glands

By means of the multilayer graphic and plastic reconstruction methods using series of semithin sections, spatial tridimensional organization of the epithelial complexes and blood microcirculatory bed in the rat palatal salivary glands and the lacrimal gland of the human newborn have been studied. Since their ducts serve not only for discharging their secrete into the external medium, but also for accumulation (as collectors), the sublobular unit--adenomere should be referred to as a part of elementary level of organization of the epithelial complexes. The adenomere has in its composition a collecting centrally situating duct. However, while studying structure of the blood microcirculatory bed, it is found out that there is not any strict territorial correspondence between its functional units and structural units of the glandular epithelium. Nevertheless, giving a great importance to a tight syntopic connection of the collecting ducts of the adenomeres with the postcapillary venules (that belong to filtrating microvessels), these are sublobular units--adenomeres that are distinguished as structural-functional units in the glands.     

Ultrastructural phosphatase histochemistry of submandibular and parotid salivary glands of man

Summary Thiamine pyrophosphatase was demonstrated in the Golgi complex and acid phosphatase in the GERL of acinar cells of submandibular and parotid glands and were previously demonstrated in cells of intercalary ducts. Thiamine pyrophosphatase was also demonstrated in the Golgi complex of cells of striated and excretory ducts and myoepithelial cells. Acid phosphatase was also demonstrated in lysosomes. Alkaline phosphatase was rarely demonstrated light microscopically at luminal surfaces of striated and excretory ducts and electron microscopically in luminal vesicles in cells of striated ducts. The demonstration of the phosphatases in Golgi complexes and GERLs indicates that investigations on these structures in experimental animals are relevant to human salivary glands and supports the opinion that ductal cells as well as acinar cells secrete organic material. The presence of alkaline phosphatase at luminal surfaces of striated and excretory ducts suggests that resorption as well as secretion may occur in them.