Control of puberty onset and fertility by gonadotropin-releasing hormone neurons

Gonadotropin-releasing hormone (GnRH) neurons exhibit many unique morphological features, including a blended dendrite–axon (dendron) that projects to the median eminence to secrete GnRH into the pituitary portal systemKisspeptin neurons in the arcuate nucleus probably represent a key component of an extrinsic pulse generator that drives pulsatile GnRH secretion in all mammalsThe preovulatory luteinizing hormone surge is driven by high follicular-phase oestradiol levels that act variably upon the neuronal surge generator and the pituitary gland among spontaneously ovulating mammalsRe-emergence of pulsatile GnRH secretion at puberty requires gonadal and non-gonadal mechanisms involving linear maturation of glial and afferent inputs alongside the resurgence of an excitatory kisspeptin inputThe GnRH neuronal network can be represented by a hierarchical modular design in which functional modules appropriate to the needs of specific mammalian species can be includedA variety of genetic mutations affect fertility, either by altering the GnRH neuron migratory pathway or by disrupting the GnRH neuron and its key neuronal regulators