Imaging of cellular aging in human retinal blood vessels.

To date two main aging vascular lesions have been reported in elderly human retinas: acellular capillaries and microaneurysms. However, their exact mechanism of formation remains unclear. Using high resolution microscopy techniques we revise cellular alterations observed in aged human retinal vessels, such as lipofuscin accumulation, caveolae malfunction, blood basement membrane disruption and enhanced apoptosis that could trigger the development of these aging vascular lesions. Moreover, we have generated a set of original images comparing retinal vasculature between middle and old aged healthy humans to show in a comprehensive manner the main structural and ultrastructural alterations occurred during age in retinal blood vessels.

Mimicking microvascular alterations of human diabetic retinopathy: a challenge for the mouse models.

Although it has become acceptable that neuroretinal cells are also affected in diabetes, vascular lesions continue to be considered as the hallmarks of diabetic retinopathy. Animal models are essential for the understanding and treatment of human diabetic retinopathy, and the mouse is intensively used as a model because of its similarity to human and the possibility to be genetically modified. However, until today not all retinal vascular lesions developed in diabetic patients have been reproduced in diabetic mice, and the reasons for this are not completely understood. In this review, we will summarize retinal vascular lesions found in diabetic and diabetic-like mouse models and its comparison to human lesions. The goal is to provide insights to better understand human and mice differences and thus, to facilitate the development of new mouse models that mimic better human diabetic retinopathy.

Immunophenotyping of lymphocyte subsets in the third eyelid tissue in dogs (Canis familiaris): morphological, microvascular, and secretory aspects of this ocular adnexa.

The third eyelid is an important adnexa of the eye. The objective of this study was to evaluate (i) morphological aspects (ii) vascularization, and (iii) the immunophenotype of lymphocyte subsets in the third eyelid of dogs. Flow cytometric analysis revealed the presence of three patterns concerning the immunophenotype of the third eyelid tissue. Dogs without ocular insult or deficient tear production might belong to one of the following immunophenotype patterns: I--the number of T-cells that expressed CD3(+) CD8(+) was higher than the number of cells that expressed CD3(+)CD4(+). II--the number of cells CD3(+)C4(+) was higher than the number of cells CD3(+)CD8(+) and in this case a higher number of cells that expressed CD19 were identified. III--Proximity of values of the cells that expressed CD3(+)CD4(+) and CD3(+)CD8(+). These data might suggest that the number of lymphocyte T cells alone should not be considered a direct indicator of the presence of an immune-based inflammation. Besides, a particular population of T-cells does not indicate a particular inflammatory state. The morphological study of the third eyelid revealed a rather uncommon angioarchitecture. The artery that irrigates the eyelid crosses almost the entire length of this structure to achieve its free border, and only then, ramificates deeply towards an inner segmental level. This spatial microvascular arrangement probably results from an adaptation to the fact that the third eyelid, in the medial cantus of the eye, is inwardly compressed into a tiny space. Efficient vascularization is achieved by allowing the first ramifications of the third eyelid artery to run straight to the top. Accini secretor cells of the third eyelid show a mucin content while tubuloacinar cells are mainly serous.