Observing three-dimensional human microvascular and myogenic architecture using conventional fluorescence microscopy.

Microangiography and vascular casting have previously been used to demonstrate the three-dimensional architecture of human uterine microvasculature. However, a limitation of these perfusion-dependent techniques is the difficulty in identifying surrounding tissue components. We have previously shown that it is possible to visualise microvascular networks on the cut surfaces of fresh tissue specimens by diffusive labelling of vascular endothelium with fluorescently conjugated UEA-1 lectin. Unlike perfusion methods that are limited to accessible vascular networks, diffusive fluorescence labelling (DFL) allows additional visualisation of extravascular cellular components, such as smooth muscle. Following UEA-1 DFL, smooth muscle-myosin and -actin were then visualised by immunolocalisation on the acetone-fixed tissue pieces. This allowed clear three-dimensional distinction between the vascular and muscle architecture of the myometrium and endometrium. This method can also be applied for studying the relative distribution of microvascular and muscle architecture in leiomyomas (fibroids). The techniques described in this methodological study provide a simple way of directly examining the uterine vasculature in three dimensions using conventional microscopy, while also distinguishing myometrial from endometrial parts of the network.