Scanning electron microscope examination of pancreatic ducts in stroke-prone spontaneously hypertensive rats (SHRSP)

Scanning electron microscopy of human islet cilia

Human islet primary cilia are vital glucose-regulating organelles whose structure remains uncharacterized. Scanning electron microscopy (SEM) is a useful technique for studying the surface morphology of membrane projections like cilia, but conventional sample preparation does not reveal the submembrane axonemal structure, which holds key implications for ciliary function. To overcome this challenge, we combined SEM with membrane-extraction techniques to examine primary cilia in native human islets. Our data show well-preserved cilia subdomains which demonstrate both expected and unexpected ultrastructural motifs. Morphometric features were quantified when possible, including axonemal length and diameter, microtubule conformations, and chirality. We further describe a ciliary ring, a structure that may be a specialization in human islets. Key findings are correlated with fluorescence microscopy and interpreted in the context of cilia function as a cellular sensor and communications locus in pancreatic islets.

Scanning electron microscopy of human islet cilia

Human islet primary cilia are vital glucose-regulating organelles whose structure remains uncharacterized. Scanning electron microscopy (SEM) is a useful technique for studying the surface morphology of membrane projections like primary cilia, but conventional sample preparation does not reveal the sub-membrane axonemal structure which holds key implications for cilia function. To overcome this challenge, we combined SEM with membrane-extraction techniques to examine cilia in native human islets. Our data show well-preserved cilia subdomains which demonstrate both expected and unexpected ultrastructural motifs. Morphometric features were quantified when possible, including axonemal length and diameter, microtubule conformations and chirality. We further describe a novel ciliary ring, a structure that may be a specialization in human islets. Key findings are correlated with fluorescence microscopy and interpreted in the context of cilia function as a cellular sensor and communications locus in pancreatic islets.

Pancreatic source of protease activity in the spontaneously hypertensive rat and its reduction during temporary food restriction

OBJECTIVE

The mechanisms underlying cell and organ dysfunctions in hypertension are uncertain. The spontaneously hypertensive rat (SHR) has elevated levels of unchecked degrading proteases compared to the control Wistar Kyoto (WKY) rat. The extracellular proteases destroy membrane receptors leading to cell dysfunctions, including arteriolar constriction and elevated blood pressure. Our goal was to identify potential sources of the uncontrolled enzymatic activity.

METHODS

Zymographic and digital immunohistochemical measurements in SHR pancreas and intestine were obtained as part of the digestive system with high levels of degrading enzymes.

OBJECTIVE

The results showed that SHRs have significantly higher protease activity than WKY in pancreas (22.04 ± 9.01 vs 13.02 ± 3.92 casein fluorescence intensity unit; P < 0.05) and pancreatic venules (0.011 ± 0.003 vs 0.005 ± 0.003 trypsin absorbance; P < 0.05) as well as in venous blood (71.07 ± 13.92 vs 36.44 ± 16.59 casein fluorescence intensity unit; P < 0.05). The enzymatic activity is contributed by trypsin and chymotrypsin. Furthermore, a decrease of these enzyme activity levels achieved during a short-term fasting period is associated with a reduction in systolic blood pressurein SHR (135 ± 8 mm Hg vs 124 ± 7 mm Hg; P < 0.05).

CONCLUSIONS

The results suggest the pancreas of the SHR is a potential source for serine proteases leaking into the circulation and contributing to its protease activity.

Scanning electron microscopic analysis of pancreatic tissue in alcoholic and tropical chronic pancreatitis

INTRODUCTION

Chronic Pancreatitis (CP) is a heterogenous disease with alcoholic chronic pancreatitis (ACP) dominating in the West, and idiopathic or tropical chronic pancreatitis (TCP) in the tropics. The aim of this study is to assess the feasibility of using a scanning electron microscope (SEM) to analyze the ultra-structural changes in alcoholic and tropical subtypes of CP.

METHODS

Chronic pancreatitis tissue samples were taken from the biopsy samples of 16 patients (seven ACP and nine TCP) who underwent drainage procedures for CP. These samples were subjected to SEM analysis and findings of normal pancreas were compared with those of CP for appreciating differences in their architectural changes.

RESULTS

Normal architecture of pancreas could be observed as lobules of parenchyma, ductal system and definite loci of Islets of Langerhans (IOL). CP samples showed loss of architecture in the form of severe fibrosis and calcifications. In ACP, the fibrosis was predominantly seen towards the periphery of the gland sparing the periductal areas. These fibres were strangulating and damaging the parenchyma. Crystals were seen over these fibres. In TCP, fibrosis was moderate and uniform throughout the parenchyma. Moreover the crystals were larger and intraluminal. Total fatty replacement of parenchyma was a striking feature in TCP, seen exclusively in diabetics with gross atrophy of IOL.

CONCLUSION

SEM gives the real-life pictures of fibrosis, fatty change, ductal changes, calcifications and thus the actual extent of damage in CP better than the ordinary light microscopy.