Postnatal development and histofunctional differentiation of the oviduct in the broad-snouted caiman (Caiman latirostris)

Abstract

Caiman latirostris is a South American crocodilian species characterized as a sentinel of the presence ofendocrine-disrupting compounds (EDCs). Evaluating developmental events in hormone-dependentorgans, such as the oviduct, is crucial to understand physiological postnatal development, to identifyputative periods of exposure sensitive to EDCs, and/or to identify biomarkers useful to evaluate theeffects of EDC exposure. In this study, we describe the histomorphological features of C. latirostris oviductsby establishing the ontogeny of changes at cellular, tissue and molecular levels from the neonatalto the pre-pubertal juvenile stages. Since the histological diagnosis of the adenogenic oviduct lies on agroup of features, here we defined a histofunctional score system and a cut-off value to distinguishbetween preadenogenic and adenogenic oviducts. Our results showed that the maturation of theC. latirostris oviduct is completed postnatally and characterized by changes that mimic the pattern ofhistological modifications described for the mammalian uterus. Ontogenic changes in the oviductalepithelium parallel changes at subepithelial level, and include collagen remodeling and characteristicspatial-temporal patterns of a-actin and desmin. The expression pattern of estrogen receptor alphaand progesterone receptor evidenced that, even at early postnatal developmental stages, the oviduct ofC. latirostris is a target organ of endogenous and environmental hormones. Besides, oviductal adenogenesisseems to be an estrogen-dependent process. Results presented here provide not only insights into thehistophysiological aspect of caiman female reproductive ducts but also new tools to better characterizecaimans as sentinels of endocrine disruption.