Follicular microvasculature in the porcine ovary

Abstract

The microvasculature of porcine ovaries, with special regard to the follicles in the interstitial-stromal tissue, was studied by scanning electron microscopy (SEM) of vascular corrosion casts. Porcine ovaries displayed several coiled arteries in the hilus and many branches with small diameters and a tightly spiraling configuration in the cortical areas. However, small arterioles became straight before entering vascular complexes of follicles and finally divided into capillaries. Vascular baskets of various sizes (150-9,900 micro m in diameter) and architecture related to follicles in various developmental stages were observed in the ovarian cortex. Small follicles (150-300 micro m in diameter) began with a polygonal meshwork of a few large capillary meshes and developed to an obvious spherical microvascular network with a thin single layer of capillaries when reaching 500-700 micro m in diameter. The microvascular architecture of follicles 1,000-2,000 micro m in diameter developed further and had a three-layer vascular plexus. With a diameter of more than 2,000 micro m, the microvasculature of antral follicles was arranged as an inner vascular plexus of about 25 micro m, a middle plexus of about 100 micro m, and an outer capillary plexus of about 30 micro m in thickness. The present observations indicate that follicular vascular baskets of diverse sizes and architecture in various developmental stages support the gradual increase of follicular blood flow during follicle growth in the pig.

Intraovarian control of selective follicular growth and induction of oocyte maturation in mammals

“…A recent study using corrosion casts for scanning electron microscopy has revealed the microvascular structure of the ovary. 9 , 10 ) For example, porcine ovaries have coiled arteries in the hilus and spiraling branches in the cortex. In addition, small arterioles originating from the cortical coiled arteries straighten before entering the vascular complexes of the follicles (Fig.…”

“…The middle layer consists of small arterioles and venules, and the outer layer is a coarse capillary plexus. 9 , 10 )…”

The hormonal composition of follicular fluid and its implications for ovarian cancer pathogenesis

“…FF is initially derived from, and is similar in composition to, thecal capillary serum [16-18]. As the follicle develops, granulosa cells produce large polysaccharides, hormones, and growth factors which cannot pass the 100 kDA follicle-blood barrier, causing an osmotic gradient which further increases FF volume [19,20].…”

Follicular Fluid redox involvement for ovarian follicle growth

“…In this respect, plasma and FF seem indistinguishable [34–36], indicating that although they are localized in distinct compartments, interchange between them exists. This is not unexpected because there is a rich vascular network around the growing follicle [37] that favors plasma proteins movement across the vessel walls into the FF compartment [38]. Whether some selectivity exists is controversial; while some suggest it [38], others argue that there is no control on the passage of molecules when ovulation approaches [39], supporting the view that the process has similarities with an inflammatory reaction [40].…”