Adaptation of reproductive activity to environmental changes is essential for breeding success and offspring survival. In mammals, the reproductive system displays regular cycles of activation and inactivation which are synchronized with seasonal and/or daily rhythms in environmental factors, notably light intensity and duration. Thus, most species adapt their breeding activity along the year to ensure that birth and weaning of the offspring occur at a time when resources are optimal. Additionally, female reproductive activity is highest at the beginning of the active phase during the period of full oocyte maturation, in order to improve breeding success. In reproductive physiology, it is therefore fundamental to delineate how geophysical signals are integrated in the hypothalamo-pituitary-gonadal axis, notably by the neurons expressing gonadotropin releasing hormone (GnRH). Several neurochemicals have been reported to regulate GnRH neuronal activity, but recently two hypothalamic neuropeptides belonging to the superfamily of (Arg)(Phe)-amide peptides, RFRP-3 and kisspeptin, have emerged as critical for the integration of environmental cues within the reproductive axis. The goal of this review is to survey the current understanding of the role played by RFRP-3 in the temporal regulation of reproduction, and consider how its effect might combine with that of kisspeptin to improve the synchronization of reproduction to environmental challenges.

The lateral periodontal cyst is a rare odontogenic cyst of developmental origin. It occurs on the lateral periodontal region of a vital tooth and has specific histologic features. In this paper a case of a lateral periodontal cyst is presented and cases previously reported in the literature are reviewed. The present case concerns a 50-year old woman who presented for an asymptomatic gingival swelling of the left canine mandibular region of 2 month's duration. X-ray examination showed a well circumscribed radiolucency with a radiopaque margin lying between the roots of the lateral incisor and canine. The associated teeth were vital. Enucleation of the lesion was performed. The histologic examination of the specimen showed a cyst lined by thin non-keratinized epithelium with focal thickenings containing clear cells.