Characterization of the fish ovarian stroma during the spawning season: Cytochemical, immunohistochemical and ultrastructural studies.

ABSTRACT

The changes in the ovarian stroma of the fish during their spawning season become it an excellent biological model for studies on cellular and vascular elements due to the intense tissue remodeling in fish occur naturally throughout this critical period. The present study aims to investigate the cellular and vascular components of the ovarian stroma of Redbelly tilapia during the spawning season by conventional, immunohistochemical stains as well as to detect the ultrastructural characteristics for each stromal component. The histological examinations revealed a series of blood vessels with special structures, include throttle artery, glomus, spirally oriented arterioles, modified arteries, and veins as well as arteriovenous anastomosis. Various types of cells were detected in the stroma include; telocytes, rodlet cells, mast cells, eosinophils, neutrophils, lymphocytes, fibroblasts, macrophages, melanocytes, adipocytes, dendritic cells, and endocrine (steroidogenic, interstitial) cells. Moreover, these stromal cells showed a broad range of staining affinity against c-kit, desmin, and s100-protein. Bundles of nerve fibers were detected between the follicles. This study exposed various cellular and vascular components with distinct functions in the ovary of Redbelly tilapia during the spawning season.