Characterization of the saccus vasculosus during early developmental stages of the cichlid fish Cichlasoma dimerus

SALLEMI, JULIETA E; DI YORIO, MARÍA P; PERNA, PAULA; PÉREZ SIRKIN; DIAZ, MARIA CANDELARIA ; VISSIO PAULA G

CABA

Congreso; 2019. 10th International Meeting of the LASDB; 2019

The saccus vasculosus (SV), an organ present in fish, is located at the floor of the hypothalamus,posterior to the pituitary gland. It is characterized by abundant sinusoidal vessels and a foldedneuroepithelium which makes a chamber that connects to the third ventricle. The epitheliumconsists of coronet cells and supporting cells, with interspersed liquor-contacting neurons. It wassuggested that SV responds to changes in the cerebrospinal fluid, but a recent work proposes that itparticipates in the control of seasonal reproduction. However, little is known about its regulation.The gonadotropin inhibitory hormone (GnIH) and neuropeptide Y (NPY) are neuropeptides whoseroles in reproduction have been widely discussed. The present study aimed to characterize theontogeny of SV in relation with these peptides. Larvae, obtained from 3 independent spawnings,were sampled from hatching to 85 days post-hatching (dph) and processed for histology andimmunohistochemistry. We observed the saccus infundibuli by 3dph and SV epithelium with 2 celltypes connecting with the lumen, by 4dph. Blood capillaries occurred in the external layer of the SVby 23dph; while by 62dph blood vessels invaded SV. NPY fibres were detected from 17dph; whileGnIH fibers were detected by 37dph depending on the size of the individuals and it does not seemto be related to gonadal differentiation. The present work comprises the starting point for futureexperiments about the role of SV during development.