Evaluation of laminin expression during mouse lens development

Among the components of the extracellular matrix [ECM] and basement membrane [BM], laminitis heterotrimeric glycoprotein [laminin] and collagen type IV are the most important. In a previous study we have examined the role of collagen type IV in the developing lens capsule. The present study aims to determine the appearance and distribution of laminin in the BM and ECM of lenses during visual system morphogenesis. Pregnant Balb/C mice were randomly selected and maintained under normal conditions. The presence of a vaginal plug was assumed as day zero of pregnancy. From embryonic days 11 to 20, pregnant animals were sacrificed and their fetuses were collected for histotechnical prossessing. Our data revealed that laminin appeared during the early stage of gestation [day 12] in the BM of the anterior epithelial lens cells. The amount of laminin gradually increased in the ECM and posterioir lens capsule epithelial cells until days 14-18. After this period, a strongly positive laminin reaction was not observed in any part of the lens structure. These findings establish the importance of the laminin molecule in the developing optic cup [OC] and lens differentiation. It could be assumed that any changes in the presence of laminin during the critical period of eye development may result in visual system defects such as cataracts or congenital eye abnormalities

immunohistochemical study of retinal collagen IV expression during pre- and postnatal periods in Balb/c mice

Basement membranes are specialized extracellular matrices which play important roles such as cell regulation, proliferation and migration. Collagen fibers, especially type IV, are the most important basement membrane constituents. As retina is one of the target organs in diabetes mellitus, and nephropathy is a major cause of end stage renal and retinal diseases resulting in increased morbidity and mortality, early diagnosis leads to better treatment. Hence, in this investigation, the appearance and distribution of collagen IV during gestational days and early postnatal periods were observed. 24 intact female Balb/c mice were kept under normal conditions. After mating, appearance of a vaginal plug was assumed as day zero of the pregnancy. From days 13-18 of gestation, the pregnant mice were euthanised and their embryos as well as pups from days 1 to 5 were collected. For histochemichal studies, heads of the specimens were fixed, serially sectioned and immunohistochemi-call studies were performed by using monoclonal antibodies for tracing of collagen type IV. Our findings revealed that the amount of collagen IV in the internal limiting membrane [ILM] and extra cellular matrix [ECM] of the retina, as well as vessels of the vitreus body appear on embryonic day 16. Also, a patchy distribution was observed in the pig-mented epithelium which continued to further develop until the end stage of embryonic life. Strong labeling was observed until postnatal day 3 but did not increase significantly thereafter. These findings establish the importance of collagen IV during the critical period of retinal development. In addition, this study indicates that high levels of collagen IV are present in the basal membrane [BM] of the inner limiting membranes and pigmented epithelium 3[rd] post natal on the 3[rd] postnatal day

role of type IV collagen in developing lens in mouse fetuses

Extracellular matrix [ECM] and basement membrane [BM] play important roles in many developmental processes during development and after birth. Among the components of the BM, collagen fibers specially type IV are the most important parts. The aim of this study was to determine the time when collagen type IV appears in the BM of lens structure during mouse embryonic development. In this experimental study, 22 female Balb/C mice were randomly selected and were kept under normal condition, finding vaginal plug was assumed as day zero of pregnancy. From embryonic day 10 to 20, all specimens were sacrificed by cervical dislocation and their heads were fixed, serially sectioned and immunohistochemistry study for tracing collagen type IV in lens were carried out. Our data revealed that collagen type IV appeared at the early stage of gestation day 12 in BM of anterior epithelial lens cells and the amount of this protein gradually increased until days 15-17 in ECM and posterior capsule epithelium. After this period, severe reaction was not observed in any part of the lens. These findings establish the important role of collagen IV in developing optic cup and any changes during critical period of pregnancy may be result in severe visual system defect