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

SALLEMI, JULIETA EMILSE; DI YORIO, MARÍA P.; PERNA, PAULA I.; PÉREZ SIRKIN, DANIELA I.; DIAZ, MARÍA C.; VISSIO, PAULA G.

Cuidad Autónoma de Buenos Aires

Congreso; Latin American Society for Developmental Biology Meeting 2019; 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 folded neuroepithelium which makes a chamber that connects to the third ventricle. The epithelium consists of coronet cells and supporting cells, with interspersed liquor-contacting neurons. It was suggested that SV responds to changes in the cerebrospinal fluid, but a recent work proposes that it participates in the control of seasonal reproduction. However, little is known about its regulation. The gonadotropin inhibitory hormone (GnIH) and neuropeptide Y (NPY) are neuropeptides whose roles in reproduction have been widely discussed. The present study aimed to characterize the ontogeny 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 and immunohistochemistry. We observed the saccus infundibuli by 3dph and SV epithelium with 2 cell types connecting with the lumen, by 4dph. Blood capillaries occurred in the external layer of the SV by 23dph; while by 62dph blood vessels invaded SV. NPY fibres were detected from 17dph; while GnIH fibers were detected by 37dph depending on the size of the individuals and it does not seem to be related to gonadal differentiation. The present work comprises the starting point for future experiments about the role of SV during development.