Abstract
Adult GnRH neurons are found scattered throughout the rostral forebrain and send a collection of morphologically unique projections to the median eminence (ME), from where GnRH is secreted in pulses to control pituitary regulation of the gonads and reproductive function. Our understanding of many critical features of GnRH neuron function, including how they integrate multiple signals, synchronise to generate pulses, respond to steroid hormone feedback and ultimately drive ovulation and spermatogenesis, has greatly benefited from our ability to visualise their morphology with both classical and recent technical approaches. The development of transgenics in the GnRH field has illuminated new regions and features of the GnRH neuron, including vast dendritic processes that undergo function‐related plasticity, bundle and receive shared synaptic input, and branch into axon‐like processes in leaky blood‐brain‐barrier areas including the median eminence. We are currently entering another technological era that will allow us to assess both the morphology and plasticity of whole GnRH neurons in situ using viral‐mediated transduction and optical clearing tools to appreciate the details of synaptic input to the distal regions of GnRH neuron dendrites. This chapter will discuss historical, recent and current methodologies in observing GnRH neuron morphology and the insights we have gained, leading to a presently proposed view of GnRH neuron morphology in the adult mammal. While some comparative aspects will be noted, the majority of work discussed here will be from studies in rodent species. A susequent focus will be made on current state‐of‐the‐art approaches that are making it possible to reveal both macro‐ and microscopic features of whole GnRH neurons in situ to understand the functional anatomy of the GnRH neuronal network in normal and pathological reproductive conditions.