Formation of the Ovarian Follicular Antrum and Follicular Fluid1

Abstract

The formation of the follicular antrum and follicular fluid has received scant attention from researchers, yet both are important processes in follicular development. The central hypothesis on follicular fluid formation suggests that production by granulosa cells of hyaluronan and the chondroitin sulfate proteoglycan versican generates an osmotic gradient. This gradient draws in fluid derived from the thecal vasculature. Inter-alpha-trypsin inhibitor is also present in follicular fluid at least in species with large follicles, and inter-alpha-trypsin inhibitor and versican could additionally bind or cross-link with hyaluronan, resulting in the retention of these molecules within the follicular antrum. Barriers to the movement of fluid across the membrana granulosa are apparently minimal, as even relatively large serum proteins are present in follicular fluid. Despite the relative permeability of the follicular wall, aquaporins are present in granulosa cells and could be actively involved in the transport of water into the follicle. The formation of an antrum also requires movement of granulosa cells relative to each other to allow the fluid to accumulate. This presumably involves remodeling of cell-cell junctions and in species with small follicles may involve death of centrally located granulosa cells. Remodeling of the stroma and thecal layers also accompanies growth and expansion of the antrum and presumably involves similar processes that accompany growth of other glands.

Follicular blood flow, antrum growth and angiogenic mediators in mares from ovulation to deviation

“…In agreement with our results, the rate at which the follicle antrum expansion and follicular fluid accumulation differs between dominant and subordinate follicles (Fortune et al, 1991;Beg et al, 2001: Beg and. In this study, by subtracting the antrum area from the follicle area around deviation we conclude that granulose layer showed no great change and the increase of the antrum area was referred to the osmotic gradient produced by granulose cells which draws in fluid derived from the thecal vasculature and to the relative permeability of the follicular wall allowing the aquaporins of the granulosa cells to be actively involved in the transport of water into the follicle (Rodgers and Irving-Rodgers, 2010), and greater thecal vascularity and blood supply of the dominant than subordinate follicles (Zeleznik et al, 1981;Redmer and Reynolds, 1996). The observed increase of the blood flow (color blood flow blue area) directed to the next dominant follicle parallel with the decrease of blood flow directed out the follicle (color blood flow red area) until completing deviation and the similar pattern of increase of percent of vascularization of the dominant follicle without antrum with the growth of the antrum confirmed the extravasations of blood leading to increased antrum area and in turn follicular fluid (Gastal et al, 1999a(Gastal et al, , 2004 and proved their role from selection to deviation.…”

“…Follicular antrum growth was studied in primate (Wulff et al, 2002) and recently several hypotheses were tested for explaining the development of follicular fluid within the antrum (Rodgers and Irving-Rodgers, 2010). Follicular fluid derives mainly from plasma via the vascular component in the follicle wall (Fahiminiya and Gérard, 2010).…”

What maintains the high intra-follicular estradiol concentration in pre-ovulatory follicles?

“…The degradation of these proteins allows for the removal of the FF in atretic follicles. Perlecan was shown to be essential for alteration of the permeability of the basal lamina, a vital stage in FF formation [49]. In addition, perlecan core protein is covalently bound to heparan sulfate (HS) chains.…”

N-glycan profiling of bovine follicular fluid at key dominant follicle developmental stages

“…There is evidence to suggest that the mechanism by which some of these factors impair fertility is attributable to their effects on the intrafollicular environment , 2011, Bender et al 2010. Follicular fluid (FF) is the product of both the transfer of blood plasma constituents that cross the blood-follicular barrier and of the secretory activity by the granulosa and thecal cells (Rodgers & Irving-Rodgers 2010). It provides a microenvironment in which the cumulus-oocyte complex can develop and mature.…”