HISTOLOGICAL STRUCTURE AND FUNCTIONAL PROPERTIES OF THE TUNICA ALBUGINEA OF THE OVARY

Abstract

Just below the surface epithelium of the ovary is the tunica albuginea, which is a tight irregular connective tissue structure that gives the tissue its white color and contains fibroblast cells. Tunica albuginea, which is more resistant to environmental factors, contains fewer cells and is rich in collagen fibers, is observed as the niche of preantral follicles. It has been observed that fibroblasts forming collagen fibers provide the development of follicles with the paracrine factors and cytokines they secrete and function as a nourishing cell layer. After the graaf follicle forms the corpus luteum, fibroblasts in the adjacent tunica albuginea proliferate and the thickness of this structure increases. The tunica albuginea undergoes frequent renewal due to the corpus luteum structures formed in rats. When the corpus luteum is formed, new capillaries and venules are formed in the adjacent tunica albuginea. This structure may be a suitable model for investigating the migration of cells from the bone marrow to the ovary via vessels. It can be suggested that mesenchymal cells and very small embryonic/epiblast-like stem cells (VSELs), which show pluripotent stem cell characteristics, may migrate from the bone marrow to the tunica albuginea through vascular structures and that the bone marrow may be the source of these cells, which have been previously shown to be present in the ovary. The aim of this review is to examine the effects of the tunica albuginea on the development of follicles and the dynamic structure of the ovary.