Morphologic Alterations of the Palpebral Conjunctival Epithelium in a Dry Eye Model

Abstract

Purpose To investigate the normal palpebral conjunctival histology in C57BL/6 mice, and the structural changes that occur in a dry eye model. Methods 24 male and female C57BL/6 mice, 8 untreated (UT) and 16 exposed to experimental ocular surface desiccating stress (DS). Ocular dryness was induced by administration of scopolamine hydrobromide (0.5 mg/0.2 ml) QID for 5 (DS5) or 10 (DS10) days. Counts and measurements were obtained using anatomical reference points and goblet cell density was investigated with a variety of stains. Results Near the junction between the lid margin and the normal palpebral conjunctiva, the epithelium had an average thickness of 45.6±10.5μm, 8.8±2.0 cell layers, versus 37.7±5.6μm, 7.4±1.3 layers in DS10 (P<0.05). In the goblet cell populated palpebral region the normal epithelium was thicker (P<0.05) than in DS5 and DS10. In the control, 43% of the goblet cells were covered by squamous epithelium, compared to 58% (DS5) and 63% (DS10) (P<0.05). A decreased number of Periodic Acid Schiff (PAS) and Alcian blue stained goblet cells was observed in the dry eye. Not all goblet cells stained with PAS and Alcian blue. Conclusions The mouse palpebral conjunctival epithelium was structurally similar to the human. After DS the palpebral conjunctival epithelium decreased in thickness and goblet cell access to the surface appeared to be inhibited by surrounding epithelial cells, potentially slowing down their migration to the surface. Differential staining with PAS and Alcian blue suggests there may be different subtypes of conjunctival goblet cells.

The palpebral conjunctival epithelium thickness in young adults measured by optical coherence tomography

“…The same is true of the palpebral conjunctival epithelium in dry eyes in mice [5]. Extrapolation of the two findings seems to support the speculation of the thinning of the palpebral conjunctival epithelium in human dry eyes or in eyes wearing contact lens.…”

“…An animal experiment has shown that the superior conjunctival epithelium is approximately 14 m thicker than the inferior [5]. Further studies are needed to ascertain if this is the case in the human and if the central region is different from the nasal or temporal region with respect to the palpebral conjunctival epithelium thickness.…”

“…The thickness of palpebral conjunctival thickness was once demonstrated on a basis of an animal experiment on mice eyes [5]: the epithelium is composed of 8.8 ± 2.0 cell layers with average thickness of 45.6 ± 10.5 m at the junction of the lid margin and palpebral conjunctiva, from which PCET tapers down to 23.50 ± 4.0 m at the place of about 1.5-2.0 mm away from the lid margin approximately corresponding to the region where PCET was measured with OCT in the present study. The mouse palpebral conjunctival epithelium is similar in structure to the human, which in turn may make sense for the comparison of the mouse PCET with the human PCET.…”

Nuclear parameters and chromatin remodeling in epithelial cells and lymphocytes from the palpebral conjunctiva of dogs with keratoconjunctivitis sicca

“…Keratoconjunctivitis sicca (KCS), more commonly known as dry eye syndrome, is a multifactorial disease of the tear film and ocular surface that results in signs of discomfort, tear film instability, intense inflammation, and visual disturbance. [1][2][3][4] It may be quantitative, characterized by a deficiency in the production of the aqueous layer of the tear film, or qualitative, characterized by changes in the lipid layer of the tear film with rapid evaporation of tears. 3 KCS commonly affects dogs and is defined as a Schirmer tear test 1 (STT1) reading of less than 10 mm/ min concomitant with pathological changes in the ocular surface.…”

“…3,6,7 With regard to the pathophysiology of KCS, recent advances in the fields of cell biology and genetics suggest that it goes beyond the histopathological manifestations seen in the lacrimal gland and the ocular surface. 2,3,[8][9][10][11][12][13] There is evidence that the metabolism of cells on the surface of the palpebral conjunctiva is also severely altered by the disease. 2 In human patients, KCS has been closely associated with changes in interphase nuclear morphology of palpebral/bulbar conjunctival epithelial cells, and with the appearance of snake-like chromatin, whose clinical and biological significances remain under investigation.…”