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

Maternal nicotine induces collagen type IV changes in the mice lung parenchyma and its vessels

One of the undesirable effects of maternal nicotine exposure during pregnancy is pulmonary hypertension. Since nicotine binds to its receptors on pulmonary vessels the hypothesis of this research was the possible structural changes that nicotine may cause on newborn vessels. Twenty-four female BALB/c mice were mated and finding vaginal plug was assumed as day zero of pregnancy. Pregnant mice were divided into 2 experimental and 2 control groups. Experimental group 1 received 3 mg/kg nicotine intraperitoneally from day 5 of gestation until the last day of pregnancy. Experimental group 2 received the same amount of nicotine during the same gestational days as well as the first 2 weeks after birth [lactation]. The control groups received the same volume of normal saline during the same periods. At the end of exposure times, all the newborns [experimental and control] were anesthetized, their lungs were removed and immunohistochemical studies were carried out for tracing collagen. Our findings indicated that collagen reaction in the bronchial basement membrane [BBM] and extracellular matrix [ECM] of the lung parenchyma in experimental groups increased significantly compared to the control groups but these changes were not observed in BM of lung vessels in the experimental groups. These data indicate that nicotine exposure during pregnancy does not cause a significant change in collagen type IV in BM of lung vessels. But this does not mean that other types of collagen fibers do not indicate change because the wall thickness of pulmonary vessels in experimental groups increased significantly compared to the control groups

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