Produção de lágrima após exérese parcial da glândula lacrimal principal em cães
Keywords:Cães, Glândula lacrimal, Lágrima, Cirurgia
: The partial loss of the lacrimal gland by obstruction, injury, removal of tumor tissue or other pathological changes may lead to loss of tear flow, bringing harmful consequences to the body. The aim was to evaluate the production of tears after removal of approximately 50% of the main lacrimal gland. Materials, Methods & Results: For this, lacrimal glands from the left eyes of seven dogs, male, adult, with weight ranging from 6 to 13kg were partially removed. In each animal, an incision of approximately 3.0 cm of skin, orbicularis and cutaneous muscle of the eye between the eyeball and the zygomatic process of frontal bone of the lateral left side was performed. After incision of the conjunctiva, close to the zygomatic process, the orbital ligament was located and partially sectioned to expose the main lacrimal gland. With a stainless steel wire graph, the gland was measured and retired approximately 50% of the parenchyma. The fragment was placed in a bottle containing 10% formalin for histological evaluation. The tears production was measured with lacrimal Schirmer test at 28 ºC and 70% relative humidity 24 hours before surgery and on the 15th, 30th and 60th days after surgery. At the 60th day, samples of gland lacrimal of the same animals were colleted for histopathologic examination of number, mean diameter of the acini and their nuclei, nucleus: cytoplasm ratio and cell area in a sample of 30 acini per animal and the density of collagen fibers. In the evaluations of the tears production with the Schirmer Test, between the pre-operative (PE), 15, 30 and 60 days post-operatively (PO) were noticed significant differences (p=0.0033) at times between PE and 15 days of PO and between 15 and 60 days of PO. By comparing histological evaluation of lacrimal gland samples in the PE and after 60 days, there were significant differences in the lacrimal gland of nuclear area (p > 0), nuclear cytoplasm proportion (p=0.0006) and cell area (p=0.0083). The collagen fibers formation did not differ significantly between PE and 60 days after partial removal of the gland (p=0.7104). All the ethical principles of ethical use of animals in experiments recommended by the Brazilian College of Animal Experimentation and Ethics Committee of the use of animals at the Federal University of Uberlandia. Discussion: The partial removal allowed the lacrimal gland remaining to offset the production of aqueous tear film: the values found in tear production were above normal throughout the trial period. Induction of cells secreting tears to hyperactivity occurred to offset the demand of production after removing part of the gland. Thus, it was stimulated increase nuclear - giant and multiple nuclei in constant transcription-protein synthesis – and small cytoplasm with little storage tear. This fact explains the increase in cell at 60 days, the decrease in tear production after 24 hours and its return to normal parameters at 60 days postoperatively. In this experiment, the density of collagen fibers found throughout the parenchyma tear between the PE and after 60 days postoperatively was not significant, possibly due to the deposition of fibers are directed to the incision site and the inflammatory reaction, along with the deposition collagen fibers was terminated with 60 days postoperatively. Therefore, the partial removal of the main tear gland in dogs does not interfere significantly in the fall of tear production on day 60 of evaluation in which the tears production came back within the normal patterns.
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