3D atlas of the pituitary gland of the model fish medaka

Abstract

In vertebrates, the anterior pituitary plays a crucial role in regulating several essential physiological processes via the secretion of at least seven peptide hormones by different endocrine cell types. Comparative and comprehensive knowledge of the spatial distribution of those endocrine cell types is required to better understand their role during the animal life. Using medaka as the model and several combinations of multi-color fluorescence in situ hybridization, we present the first 3D atlas revealing the gland-wide distribution of seven endocrine cell populations: lactotropes, thyrotropes, Lh and Fsh gonadotropes, somatotropes, and pomca-expressing cells (corticotropes and melanotropes) in the anterior pituitary of a teleost fish. By combining in situ hybridization and immunofluorescence techniques, we deciphered the location of corticotropes and melanotropes within the pomca-expressing cell population. The 3D localization approach reveals sexual dimorphism of tshba- and pomca-expressing cells in the adult medaka pituitary. Finally, we show the existence of bi-hormonal cells co-expressing lhb-fshb, fshb-tshba and lhb-sl using single-cell transcriptomics analysis and in situ hybridization. This study offers a solid basis for future comparative studies of the teleost pituitary and its developmental plasticity.

Estrogen mediates sex differences in preoptic neuropeptide and pituitary hormone production in medaka

“…We further investigated the identity of the pituitary cells expressing these receptors. The RPD of teleosts, including medaka, contains prolactin (prl)-and pro-opiomelanocortin (pomc)-expressing cells, whereas the PI contains somatolactin (sl)-and pomcexpressing cells 28 . Double in situ hybridization for the receptors and pituitary hormone genes showed that adcyap1r1a was expressed in pomc-, but not prl-expressing, cells in the RPD and adcyap1r1b and vipr2b were exclusively expressed in sl-and pomc-expressing cells, respectively, in the PI (Fig.…”