The Vascular Microarchitecture of the Human Fetal Pancreas: A Corrosion Casting and Scanning Electron Microscopy Study.

OBJECTIVES: Detailed knowledge on the development of the pancreas is required to understand the variability in its blood supply. The aim of our study was to use the corrosion casting method combined with scanning electron microscopy to study the organization of the pancreatic microcirculation in human fetuses. METHODS: The study was conducted on 28 human fetuses aged 18 to 25 gestational weeks. The fetal vasculature was appropriately prepared and then perfused with a low-viscosity Mercox CL-2R resin. The prepared vascular casts of the surface of the fetal pancreas were then examined in scanning electron microscopy and digitally analyzed. RESULTS: The lobular structure of the pancreas has a strong impact on the organization of the microvasculature. The lobular networks were supplied by the interlobular arteries and drained by the interlobular veins. The vascular system of fetal human pancreas has many portal connections, including islet-lobule and islet-duct portal circulations, which likely play a key role in the coordination of both endocrine and exocrine pancreatic functions. CONCLUSIONS: The organization of the microvascular network of the human pancreas in fetuses aged 18 to 25 gestational weeks is very similar to that of an adult but with more prominent features suggesting active processes of angiogenesis and vascular remodeling.

Vascular system of human fetal pancreas demonstrated by corrosion casting and scanning electron microscopy.

Vascular architecture of the human pancreas was investigated by corrosion casting combined with scanning electron microscopy in fetuses aged 20 and 25 gestational weeks. The general pattern of the microvascular system was similar to that of the postnatal pancreas, with an evident insulo-acinar portal system and with three types of capillary networks: capillaries of exocrine lobules, islet capillaries and periductal capillaries around large ducts located in the interlobular septa. All these capillary networks were supplied by arteriolar branches of the interlobular arteries. As compared with the postnatal pancreas, capillaries of exocrine lobules formed denser meshworks, had a more sinusoidal character and revealed morphological features indicative of angiogenesis (blind capillary sprouts). The number of efferent (portal) capillaries per islet was lower and the predominant pattern of islet vasculature was top to bottom rather than inner to outer, as observed in adults. These results show that in the second trimester the human pancreatic vascular architecture is almost completely developed and requires only minor remodeling to be fully functional in the postnatal period.

Application of acrylic emulsion Liquitex R (Binney and Smith) for the preparation of injection specimens and immunohistochemical studies--an observation.

Application of acrylic emulsion Liquitex R for injection studies of the vascular system of human myomatous uteri was analysed. It was found that this injection mass does not penetrate the capillary bed of human organs, but it is useful in studies carried out on the blood supply of the human organs removed from cadavers. The results were compared with the studies performed with the help of immunohistochemical tests for von Willebrandt's factor.

Application of a mixture of glycol polyethylenes for the preparation of microcorrosion casts--an observation.

Preparation of microcorrosion casts that can be used for observation in SEM is a laborious, time-consuming procedure. The authors paid particular attention to the process of dissection of the microcorrosion casts. This prompted the authors to reconstruct the plastic mass, produced by the firm Gurr (Great Britain) in the 1970s, which was used by them in previous research to immerse the cast in order to minimise the damage. By using easily obtainable polyethylene glycols, characterised by different physical and chemical features, in order to obtain smooth surface of the section, a low-toxic mixture was composed, which protected the microcorrosion casts sufficiently and did not interfere with the physical and chemical properties of the cast.