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

SALLEMI JULIETA; DI YORIO, MARÍA P.; PERNA P; PEREZ SIRKIN, DANIELA; DÍAZ, MANUEL; VISSIO, PAULA G.

Congreso; LATIN AMERICAN SOCIETY FOR DEVELOPMENTAL BIOLOGY (LASDB) MEETING 2019; 2019

The saccus vasculosus (SV), an organ present in fish, is located at the floor of thehypothalamus, posterior to the pituitary gland. It is characterized by abundantsinusoidal vessels and a folded neuroepithelium which makes a chamber thatconnects to the third ventricl e. The epithelium consists of coronet cells andsupporting cells, with interspersed liquor contacting neurons. It was suggested thatSV responds to changes in the cerebrospinal fluid, but a recent work proposes thatit participates in the control of season al reproduction. However, little is knownabout its regulation. The gonadotropin inhibitory hormone (GnIH) and neuropeptideY (NPY) are neuropeptides whose roles in reproduction have been widelydiscussed. The present study aimed to characterize the ontoge ny of SV in relationwith these peptides. Larvae, obtained from 3 independent spawnings, weresampled from hatching to 85 days post hatching (dph) and processed for histologyand immunohistochemistry. We observed the saccus infundibuli by 3dph and SVepith elium with 2 cell types connecting with the lumen, by 4dph. Blood capillariesoccurred in the external layer of the SV by 23dph; while by 62dph blood vesselsinvaded SV. NPY fibres were detected from 17dph; while GnIH fibers weredetected by 37dph dependin g on the size of the individuals and it does not seem tobe related to gonadal differentiation. The present work comprises the starting pointfor future experiments about the role of SV during development.