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This study was designed to evaluate follicular development of 30 postpartum beef cows: 15 were suckled, and calves were removed from the other 15 within 24 h after birth. Ovaries were removed on Day 5 postpartum and a total of 246 follicles greater than or ≥3 mm in diameter was obtained. Estrogen was extracted from follicular fluid and quantitated by radioimmunoassay. Atresia for each follicle was assessed by 1) follicular estrogen concentrations, and 2) evaluating mitotic and pyknotic nuclei in granulosa cells. The average weight of the ovaries and corpus lutea (CLs) did not differ between cow treatments or between locations relative to the right or left ovary. Suckled cows had smaller and fewer follicles and follicular estrogen concentrations were lower compared with follicles from nonsuckled cows. The ovary with the CL which was ipsilateral to the uterine horn of the recent pregnancy (CL ovary) compared with the ovary without the CL (non-CL ovary) had smaller follicles and lower estrogen concentrations. Only 18% of the follicles on the CL ovary compared to 48% of the follicles on the non-CL ovary were classified as healthy. The interaction of suckling and the presence of the CL significantly depressed follicular development. Follicles on the non-CL ovary from nonsuckled cows had the greatest estrogen content and percent of healthy follicles. Suckling significantly decreased follicular estrogen concentrations and the percent of healthy follicles on the non-CL ovary, and estrogen concentrations and the percentage of healthy follicles were lowest on the CL ovary from suckled cows.

Porcine granulosa cells were incubated with commercially available glycosaminoglycans (GAGs) or GAGs purified from porcine follicular fluid to evaluate the effects of GAGs on degradation of low-density lipoproteins (LDL) and progesterone production. Commercially available heparin and chondroitin sulfates (CS) as well as follicular CS and heparan sulfate (HS) inhibited degradation of LDL in dose-dependent manners. Doses of follicular CS and HS required to inhibit 50% of the LDL degradation corresponded to concentrations found in follicular fluid (< 1 mg/ml). Progesterone production was also inhibited in a dose-dependent fashion by follicular GAGs at concentrations found in follicles. The ability of the follicular GAGs to inhibit degradation of LDL could represent a mechanism by which the utilization of LDL-derived sterol is temporarily restricted following permeabilization of the ovulatory follicle. Follicular GAGs may also modulate utilization of apoprotein E-containing high-density lipoproteins in unruptured follicles.

Glycosaminoglycans (GAGs) were purified from bovine follicular fluid, and their effectiveness to compete for heparin-binding sites in granulosa cells was evaluated. The GAGs dermatan sulfate (DS) and heparan sulfate (HS) were purified by anion-exchange high-performance liquid chromatography. Approximately 5 µg of protein from suspensions of bovine granulosa cells were incubated with 101 pmoles of [3H]heparin and 0.01–5.0 mg/ml of HS or DS for 2 h at 37°C in 40 mM tris(hydroxymethyl)aminomethane (Tris), pH 7.35. Heparan sulfate obtained from small and medium follicles displaced [3H]heparin in a dose-dependent manner from 0.1 to 5 mg/ml, but HS from large follicles did not displace [3H]heparin. The DS obtained from small, medium, and large follicles displaced [3H]heparin in a dose-dependent manner, and the potency of the DS to displace [3H]heparin increased as the size of the follicles from which the DS was purified increased. Those results were independent of the maturational state of the granulosa cells. In a separate experiment, heparin (17.1% sulfate) was N-desulfated (11.8%), and the desulfated heparin did not displace [3H]heparin. It was concluded that the effectiveness of follicular HS and DS to compete for heparin-binding sites on granulosa cells was dependent on the maturation of the follicle from which the fluid was obtained rather than on the source of granulosa cells. The binding interaction of the GAGs relies, to some extent, on the presence and positions of sulfate moieties.

Acetone precipitates of bovine follicular fluid from small (3–5 mm) and large (10–20 mm) follicles were fractionated by nondissociative procedures involving chromatography on Sephacryl S-300, DEAE cellulose, and Sepharose CL-2B. Most of the proteoglycan material eluted with a relatively low molecular weight (Kav= ~ 0.6) from Sepharose CL-2B.Comparisons of the proteoglycans from small versus large follicles showed respective differences of 20 versus 34% protein, 74 versus 48% chondroitin sulfate-B, and 4 versus 8% other sugars. The protein moiety of the proteoglycan from small follicles exhibited greater proportions of aspartic acid, serine and glycine, but lower proportions of theonine, alanine and valine, than its analog from large follicles.Chromatography on Sepharose CL-2B in 4 M guanidine-HCl failed to alter the elution position of the proteoglycans. However, noticeable decreases occurred in the protein and total amino acid content of the proteoglycans, especially from large follicles, suggesting preparations obtained from the nondissociative procedures contained aggregates of peptides, glycosaminoglycans, and/or proteoglycan fragments. Proteoglycans from both sizes of follicles were enriched in serine, glutamic acid and glycine, but diminished in leucine and lysine following the dissociative gel filtration. Differences in composition of the proteoglycans may be related to follicular differentiation.