Zygomatic Gland

Abstract:This article describes three original cases of zygomatic gland disease in the dog diagnosed by low-field MRI and treated by a modified lateral orbitotomy with zygomatic osteotomy. Presenting complaints included exophthalmia, protrusion of the third eyelid, and periorbital swelling without any history of trauma. Low-field MRI allowed for adequate diagnosis of zygomatic gland disease in all cases and provided detailed information about both the specific tissue characteristics of each lesion and extension into surrounding structures. MRI findings were also helpful for surgical planning and dictated the choice of a modified lateral orbitotomy without removal of the orbital ligament. Histopathologic diagnosis for each of the three dogs was a mucocele, a malignant mixed salivary tumor, and sialadenitis.

Abstract:A seven-year-old male, entire rottweiler was presented to Murdoch University Veterinary Hospital with a 24 hour history of blindness, chemosis, exophthalmus, pain on opening the mouth and hypersialism. Bilateral mandibular and zygomatic salivary gland enlargement with concurrent bilateral zygomatic salivary gland sialocoeles were identified. The cause of the mandibular salivary gland enlargement was confirmed as necrotising sialadenitis, while the cause of the zygomatic gland enlargement was presumed to be because of a similar disease process. No underlying aetiology was identified. Treatment consisted of supportive management, corticosteroids and paracentesis of the sialocoeles and resulted in resolution of the salivary gland enlargement and the associated clinical signs. This is an unusual presentation of salivary gland disease in the dog with multiple gland involvement and a spectrum of disease processes occurring at the same time.

Abstract:The zygomatic gland of the cat consists of at least two parts, separated by a septum, and each drains by a separate duct opening on a mucosal ridge postero-medial to the parotid orifice It is composed on thin-walled ducts and tubulo-acini, containing mainly mucous cells, but scattered cap cells are also present In cats under chloralose anaesthesia there is a spontaneous flow of extremely viscous saliva and often, in addition, there is a reflexly elicited component to the secretion In fact, in contrast to the other major salivary glands, the zygomatic gland is easily made to secrete reflexly even in deep] anaesthesia, eg by pinching ipsilateral parts of the tongue, by stimulation of the oesophagus mimicking swallowing, or by afferent excitation of ipsilateral lingual, glossopharyngeal or vagal nerves The efferent link of the reflex arc is contained in the buccal branch of the mandibular nerve Section of this nerve abolishes these reflexes, and two weeks later a great loss of acetylcholinesterase positive nerves can be demonstrated in the gland Efferent stimulation of the buccal nerve evokes a lively secretion that is not affected by hexamethonium but is abolished by atropine Histochemically, adrenergic nerves are also found surrounding the acini and these nerves disappear after excision of the superior cervical ganglion Electrical stimulation of the cervical sympathetic trunk causes some secretion, mainly by way of beta 1-adrenoreceptors Myoepithelial cells are present around the tubulo-acini, and indications of the effect caused by their contraction on the flow from the glands have been observed Such activity can be induced reflexly and it is then abolished by cutting the buccal nerve or by injecting atropine

Abstract:Summary The mucosubstances of the major salivary glands of the ferret were analysed using different histochemical reactions. Almost all the parotid acinar cells had sialic acid-containing mucus. There were a very few cells, the granules of which gave reactions for sulphated mucins. Submandibular gland mucus was sulphated in the major parts of the gland. There were occasional cells which gave reactions to carboxylated mucin. The sublingual and the molar glands had tubules which had 2 types of mucous cells. The central cells contained sulphated mucins and the peripheral ones had carboxylated mucins. The mucus in the tubules of the zygomatic gland was predominantly sulphated. In the sublingual, molar as well as in the zygomatic, there were granulated cells scattered among the tubules. Some of these granules were found to contain carboxylated and the others neutral mucins. No sexual dimorphism was observed in any of the glands among the 4 male and 4 female ferrets used in this study.

Abstract:唾液分泌的研究通常集中on parotid and submandibular glands. However, the film of mucin, that protects the oral structures and is responsible for the feeling of oral comfort, is produced by the submucosal glands. The submucosal zygomatic and molar glands are particularly large in carnivores such as the ferret. Comparisons between the mucous sublingual, zygomatic and molar glands, serous parotid and sero-mucous submandibular glands showed the acetylcholine synthesis, in terms of concentration, to be three to four times higher in the mucous glands than in the parotid and submandibular glands. Bromoacetylcholine inhibited 95-99% of the synthesis of acetylcholine in the incubates of the five types of glands, showing the acetylcholine synthesis to depend on the activity of choline acetyltransferase. The high acetylcholine synthesis in the zygomatic gland was of nervous origin, since cutting the buccal nerve, aiming at parasympathetic denervation, and allowing time for nerve degeneration, reduced the acetylcholine synthesising capacity of the gland by 95%. A similar reduction (96%) in the parotid gland followed upon the avulsion of the parasympathetic auriculo-temporal nerve. Zygomatic saliva was very viscous. The salivary flow rate in response to electrical stimulation (20 Hz) of the buccal nerve (zygomatic gland), expressed per gland weight, was one-third of that to stimulation of the auriculo-temporal nerve (parotid gland) or the chorda-lingual nerve (submandibular gland). As previously shown for the parotid and submandibular gland, a certain fraction (25%) of the parasympathetic secretory response of the zygomatic gland depended on non-adrenergic, non-cholinergic transmission mechanisms, probably involving substance P and vasoactive intestinal peptide and possibly calcitonin gene-related peptide. Particularly, high concentrations of vasoactive intestinal peptide were found in the sublingual and molar glands, and of substance P in the submandibular, zygomatic and molar glands; notably, the concentration of calcitonin gene-related peptide of the sublingual gland was not detectable. All five muscarinic receptor subtypes were detected in the five glands. The receptor protein profile, as judged by immunoblotting and semi-quantitative estimations, was about the same in the glands: high level of M3, low level of M2 and levels roughly in the same range of M1, M4 and M5. Compared to the parotid and submandibular glands, the M5 receptor level was particularly low in the mucin-secreting glands. The present study points out both similarities and dissimilarities between the five types of glands investigated. The zygomatic gland, in particular, appears to be a suitable model for future studies aiming at causing relief of dry mouth by local pharmacological treatment.