Microvascular Changes During the Development of Follicles in Bovine Ovaries: A Study of Corrosion Casts by Scanning Electron Microscopy.

Abstract

Summary. Microvascular changes during the development of follicles in bovine ovaries were studied by scanning electron microscopy of corrosion casts. A clear vascular plexus of ovarian follicles appeared at the stage when secondary follicles were 200-400um in diameter. The plexus consisted initially of a thin, roughly structured and single-layered capillary network.During follicular development, the microvascular architecture of antral follicles was arranged as two independent vascular plexuses. The inner plexus, which received a spiral arteriole, consisted of a dense sinusoidal capillary network with an arterial and a venous layer; it functioned as an independent microcirculatory unit. The inner plexus developed from the capillary plexus of the theca interna of the secondary follicles. The outer plexus, which anastomosed with several stromal capillaries, consisted of a thin, coarse and basket-like capillary plexus. The outer plexus was formed from the stromal capillary plexus as a consequence of the rapid enlargement of developing antral follicles.

Changes in the Thecal Vasculature During Follicular Atresia in the Ovary of Swamp Buffalo

“…This is in agreement with reports on other species of animal [1][2][3]12]. Additionally, scanning electron microscopy studies of ovarian follicle corrosion casts of various animals revealed similar observations [5,[13][14][15][16][17]. Thus, these findings support the concept that follicular atresia is accompanied by significant thecal capillary structural changes [18].…”

Increased ovarian follicular angiogenesis and dynamic changes of follicular vascular plexuses induced by equine chorionic gonadotropin in the gilt

“…Follicular development and atresia is accompanied by significant structural and functional changes of the thecal capillary (Macchiarelli 2000). It has been reported in rabbits (Kanzaki et al 1982;Kikuta et al 1991;Kitai et al 1985;Macchiarelli 2000), cows (Yamada et al 1994(Yamada et al , 1995 and pigs ) that the single-layered capillary wreath in the small-sized follicles develops into a multilayered structure in the thickened theca interna as the follicles develop into larger and more mature Graafian follicles, and that the maintenance of the follicular vasculature is important for follicular health (Mattioli et al 2001). Indeed, large healthy bovine follicles have a high density of well-developed capillaries with extensive This work was supported by grants from the Program for Promotion of Basic Research Activities for Innovative Biosciences and "Research for the Future" Program, the Japan Society for the Promotion of Science (JSPS-RFTF97L00904) and the Canadian Institutes of Health Research (MOP-15691).…”

“…The paucity of information to date may in part be due to the complexity of current approaches [such as serial sections and vascular corrosion casting associated with scanning electron microscopy (SEM)] used to study follicular angiogenesis. While tracing of the entire capillary in serial sections, especially for a large number of follicles, is labor intensive and time consuming, SEM with corrosion casts, which has been used widely for the detailed morphological analysis of microvascular systems (Forsman and McCormack 1992;Macchiarelli et al 1995;Murdoch and Cavender 1989;Shimoda et al 1993;Yamada et al 1995), offers no information on the follicular status (healthy or atresia). We have recently developed an experimental approach in which SEM of corrosion cast was used successfully in combination with follicular fluid steroid analysis to assess follicular angiogenesis and capillary degeneration in healthy and atretic bovine follicles (Jiang et al 2003).…”

The Microvasculature of the Ovary. A Review by SEM of Vascular Corrosion Casts.

“…At present, scanning electron microscopy (SEM) of vascular corrosion casts allows the best morphological 3D reconstruction of the vascular supply, including its finest ramifications, in both normal and experimental conditions, as observed in ovary of rodents [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41], horses [42], cows [43,44] and sheep [45,46]. This technique allowed significant information on the ovarian cycle, and better clarified the role of vascular morphodynamics in the development of the LFC [37,[47][48][49].…”