@article{cushman_desouza_hedgpeth_britt_2001, title={Alteration of activation, growth, and atresia of bovine preantral follicles by long-term treatment of cows with estradiol and recombinant bovine somatotropin}, volume={65}, ISSN={["0006-3363"]}, DOI={10.1095/biolreprod65.2.581}, abstractNote={Abstract The hypothesis was that long-term treatment of cattle with estradiol (E2) and bovine somatotropin (bST) would alter the earliest stages of folliculogenesis. Nonlactating Holstein cows (n = 26) were treated in a 2 × 2 arrangement with E2 (2 × 24 mg implants, 67.1 ± 1.4 days) and bST (Posilac, 63.6 ± 1.5 days). At Day 67 ± 1.3, one ovary was removed for morphometric and immunohistochemical analysis. For each ovary, 388 ± 38 microscopic fields (2 × 2 mm) were examined and follicles within each field were classified by histological stage. Fields that contained no follicles were classified as empty. Empty fields (n = 100 per ovary) were further classified as containing no evidence of follicles or containing atretic remnants of follicles. Approximately 30 4-μm sections per ovary were stained for proliferating cell nuclear antigen (PCNA), and 150 fields per ovary were evaluated. Additional sections (n = 10 per ovary) were assessed immunohistochemically for apoptosis, and fluorescence intensity was determined for each follicle. Treatment with bST significantly decreased percentage of empty fields containing atretic remnants. Treatment with E2 induced activation of follicles as shown by a decrease in percentage of primordial follicles and an increase in percentage of primary follicles as determined by PCNA staining. At the primary follicle stage the combination of bST + E2 decreased apoptosis as shown by decreased fluorescence intensity. Thus, E2 induced activation of follicles, bST enhanced survival, and the combination lowered atresia.}, number={2}, journal={BIOLOGY OF REPRODUCTION}, author={Cushman, RA and DeSouza, JC and Hedgpeth, VS and Britt, JH}, year={2001}, month={Aug}, pages={581–586} }
 @article{cushman_desouza_hedgpeth_britt_2001, title={Effect of long-term treatment with recombinant bovine somatotropin and estradiol on hormone concentrations and ovulatory response of superovulated cattle}, volume={55}, ISSN={["0093-691X"]}, DOI={10.1016/S0093-691X(01)00500-3}, abstractNote={The objective was to assess effects of long-term treatment with recombinant bovine somatotropin (bST) and estradiol-17β (E2) on the number of follicles that ovulated in response to FSH. Non-lactating Holstein and Jersey cows (Trial 1, n=27) and Angus cows and heifers (Trial 2, n=35) received two ear implants of E2 and biweekly injections of bST in a 2 × 2 arrangement of treatments. Estradiol implants were removed 74.6 ± 1.1 d after insertion and 18.1 ± 0.9 d after the last biweekly injection of bST. Cows were stimulated with FSH-P beginning 2 d after removal of E2 implants, and PGF2alpha (PGF) was given on the third day of FSH treatment Ovaries were collected to determine the number of CL at 1 to 2 wk after treatment with PGF. In Trial 2 only, cattle were inseminated at estrus and embryos were collected 6 to 8 d later. Implants of E2 increased (P < 0.01) serum E2 8-fold initially and E2 was still elevated 5-fold at removal of implants. Injections of bST increased (P < 0.01) serum growth hormone (GH) 15-fold and insulin-like growth factor-I (IGF-I) 3-fold. In Trial 1, number of CL was increased by the combination of bST+E2 (P < 0.01). In Trial 2, E2 increased the number of CL (P < 0.05), and bST increased the number of total ova and transferable embryos (P < 0.01). We conclude that long-term treatment with bST and E2 may interact to enhance follicular development and ovulatory response to FSH.}, number={7}, journal={THERIOGENOLOGY}, author={Cushman, RA and DeSouza, JC and Hedgpeth, VS and Britt, JH}, year={2001}, month={Apr}, pages={1533–1547} }
 @article{cushman_hedgpeth_echternkamp_britt_2000, title={Evaluation of numbers of microscopic and macroscopic follicles in cattle selected for twinning}, volume={78}, DOI={10.2527/2000.7861564x}, abstractNote={We hypothesized that the number of microscopic follicles present in the ovaries of cattle selected for twin births (Twinner) would be greater than in the ovaries of contemporary Controls. Ovaries were collected from seven Control and seven Twinner cows at slaughter. The number of Small (1 to 3.9 mm), Medium (4 to 7.9), and Large (> 8 mm) surface follicles was counted and one ovary was fixed for histological evaluation. Fifty to sixty consecutive 6-microm slices were taken from a piece of cortical tissue, approximately 1 cm x 1 cm in area, located between the surface follicles. Microscopic follicles were classified as primordial (oocyte surrounded by a single layer of squamous pregranulosa cells), primary (oocyte surrounded by a single layer of one or more cuboidal granulosa cells), secondary (oocyte surrounded by two or more layers of granulosa cells), or tertiary (oocyte surrounded by multiple layers of granulosa cells with initiation of antrum formation to < or = 1 mm in diameter). The total number of follicles was counted in 200 fields (2 mm x 2 mm) per ovary. A field containing no follicles was classified as empty. There were significantly more secondary follicles in Twinner compared with Control ovaries (12.9 vs 6.3; P < .05). Twinners also tended to have more small surface follicles (35.4 vs 49.0; P < 0.1). We conclude that ovaries of Control and Twinner cows do not differ in the number of primordial follicles or in the number of follicles activated into the growing pool; however, Twinner cows are able to maintain more growing follicles at the secondary and subsequent stages of development.}, number={6}, journal={Journal of Animal Science}, author={Cushman, R. A. and Hedgpeth, V. S. and Echternkamp, S. E. and Britt, Jack}, year={2000}, pages={1564–1567} }
 @article{cushman_desouza_hedgpeth_britt_1999, title={Superovulatory response of one ovary is related to the micro- and macroscopic population of follicles in the contralateral ovary of the cow}, volume={60}, ISSN={["1529-7268"]}, DOI={10.1095/biolreprod60.2.349}, abstractNote={We hypothesized that the ovulatory response of one ovary to FSH would be related positively to the size of the primordial and growing pools of follicles in the other ovary. Nonlactating cows (n = 26) were unilaterally ovariectomized and 2 days later were superovulated. The superovulatory response was classified as Low (< 5 corpora lutea [CL]), Medium (5-14 CL), or High (> 14 CL). Surface follicles on the ovary removed before superovulation were classified as small (1-3 mm), medium (3-7 mm), or large ( > 7 mm), and the ovary was then fixed and serially sectioned. Follicles </= 1 mm in diameter in 388 +/- 38 fields (2 x 2 mm) per cow were classified as primordial, primary, secondary, or tertiary. By classification, Suboptimal ovaries contained < 100 follicles </= 1 mm and Optimal ovaries contained > 250 follicles </= 1 mm. Number of CL was correlated positively with total number of primordial, tertiary, and medium surface follicles. Number of Empty fields (2 x 2-mm fields containing no follicles) was correlated negatively with superovulatory response and number of primordial follicles. Number of CL was related to number of tertiary follicles in a positive linear manner and the number of medium follicles in a positive quadratic manner (r 2 = 0.66). Numbers of primordial, tertiary, small surface follicles, medium surface follicles, and total surface follicles were lower (p </= 0.06) in the Low superovulatory response group than in the Medium or High group. Suboptimal ovaries had fewer small surface follicles and fewer CL than Optimal ovaries (p < 0.05). We conclude that superovulatory response in cattle is related positively to the pools of primordial and growing follicles in the bovine ovary.}, number={2}, journal={BIOLOGY OF REPRODUCTION}, author={Cushman, RA and DeSouza, JC and Hedgpeth, VS and Britt, JH}, year={1999}, month={Feb}, pages={349–354} }
 @article{cushman_davis_boonyaprakob_hedgpeth_burns_britt_1999, title={Technical note: Use of slow-release estradiol and prostaglandin F-2 alpha to induce pseudopregnancy and control estrus in gilts}, volume={77}, DOI={10.2527/1999.77112883x}, abstractNote={We determined whether a single injection of slow-release estradiol-17beta (SRE2) would induce pseudopregnancy in gilts and whether PGF2alpha would regress the corpora lutea (CL) of pseudopregnancy. Crossbred gilts (n = 40) were induced to ovulate by treatment with 400 IU of hCG + 200 IU of eCG (PG600, Intervet, Millsboro, DE) given at 180 d of age (d = 0). On d 14, gilts were injected i.m. with one of five doses (n = 8 gilts/dose) of SRE2 (0, 12.5, 25, 50, or 100 mg). Blood samples were collected before SRE2 and twice weekly until d 73 to monitor serum progesterone (P4) and estradiol (E2). On d 59, gilts received (i.m.) 10 mg of PGF2alpha (Lutalyse, Pharmacia Upjohn, Kalamazoo, MI) and were checked for estrus for 7 d. On d 62, mammary development was scored (0 = no development; 1 = some development; 2 = teat and gland development) by a neutral observer. Treatment with SRE2 increased (P < .05) peak E2 concentrations, duration of luteal function, and mammary gland score. There were no differences (chi-square, P > .05) among doses of SRE2 in the percentage of pseudopregnant gilts that showed luteolysis after PGF2alpha. We conclude that a single injection of SRE2 can induce pseudopregnancy and that the CL can be regressed with PGF2alpha, providing a simple method for controlling estrus in gilts.}, number={11}, journal={Journal of Animal Science}, author={Cushman, R. A. and Davis, P. E. and Boonyaprakob, U. and Hedgpeth, V. S. and Burns, P. J. and Britt, Jack}, year={1999}, pages={2883–2885} }
 @article{britt_cushman_hedgpeth_shaw_1999, title={Use of an ovarian biopsy to predict surface follicle numbers on the bovine ovary.}, volume={60}, number={1999}, journal={Biology of Reproduction}, author={Britt, J. H. and Cushman, R. A. and Hedgpeth, V. S. and Shaw, D. W.}, year={1999}, pages={107} }