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.