Figure 1 The ejaculation reflex and ejaculatory control Figure 1 | The ejaculation reflex and ejaculatory control. Ejaculation is the result of the coordinated contractile activity involving different ejaculatory organs organized by the spinal ejaculatory generator, located at the T12–L1–L2 level of the spinal cord. Afferent information is received by the spinal ejaculatory generator, which coordinates sympathetic, parasympathetic, and motor outflow for the two phases of ejaculation—emission and expulsion. The SEG integrates these inhibitory and excitatory influences from supraspinal sites, as well as inputs conveying biochemical or mechanical information from the accessory sex organs. Emission of semen involves the sympathetic efferent fibres of the 'secretory centre' (T10–L2) coordinating sequential contractions of the epididymis, vas deferens, seminal vesicles, and prostate with associated closure of the bladder neck. Expulsion of semen is then initiated somatically by the 'mechanical centre' of the sacral spinal cord (S2–S4) via the pudendal nerve, which induces contractions of the bulbospongiosus, bulbocavernous and perineal muscles, which, in turn, rhythmically force the ejaculate through the distal urethra. Abbreviation: SSRI, selective 5-hydroxytryptamine reuptake inhibitor. Saitz, T. R. & Serefoglu, E. C. (2015) Advances in understanding and treating premature ejaculation Nat. Rev. Urol. doi:10.1038/nrurol.2015.252