Solving the puzzle of the human pelvic plexus: a developmental and multiscale imaging approach

These projects will use large-volume tissue clearing and state-of-the-art three-dimensional (3D) light-sheet imaging of human embryo specimens to describe the ontogeny and organisation of the sexually dimorphic human pelvic plexus (also known as the pelvic ganglia or inferior hypogastric plexus) and its connections with the spinal cord. The project design incorporates specific parallel studies in mice, to maximise the translatability of new knowledge.

At the University of Melbourne, the focus will be on the spinal cord. This contains neural circuits required for both ‘involuntary’ (autonomic) regulation of pelvic organs and volitional motor control of sphincters and pelvic floor muscles. The project design will incorporate recent data from transcriptomic profiling of adult mouse spinal cord and sensory neurons to identify the developmental processes within spinal circuits. This approach will also provide novel tools to examine distinct neuron populations within the developing human spinal cord. Detailed characterization of synaptic connections with the pelvic plexus may then be examined further using super-resolution or ultrastructural approaches.

The CNRS based project will focus on the human pelvic plexus. These highly complex aggregations of neurons located in the pelvis are responsible for the autonomic regulation of urogenital organs and coordination of many of their critical functions. Specific parallel studies will be performed in mice. This project will use a vast library of pre-validated primary antibodies to reveal the neurotransmitter and transcriptional identities of pelvic ganglion neurons and describe their connectivity.

Data from both projects will be analysed using innovative pipelines, including virtual reality to visualise and accurately segment data in 3D. It will apply both machine learning and deep learning models for unattended image analysis for unbiased quantitative data segmentation.

The aim of the proposed projects is to provide the first extensive visualization and analysis of two areas of the developing human nervous system: the lumbosacral spinal cord and the pelvic plexus (pelvic ganglia). Specific aspects of this neural circuit development will also be examined in mice. The outcomes will provide the first insights into the developmental processes underlying this complex neuronal network that uniquely merges autonomic and volitional motor systems.

The projects will build the first 3D atlases of the neuronal organisation and axonal connectivity of the developing human pelvic plexus and lumbosacral spinal cord. These fundamental resources will benefit researchers, anatomists and clinicians. Selected parallel studies on developing mouse systems will provide new mechanistic insights that can be examined experimentally in the developing mouse system.