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Topic:In Vitro Research

In vitro research involving horses refers to the study of equine cells, tissues, or biological molecules outside their normal biological context, typically in controlled laboratory environments. This research approach allows scientists to investigate cellular processes, molecular interactions, and the effects of various treatments without the ethical and logistical complexities of in vivo studies. In vitro studies contribute to understanding equine physiology, pathology, and pharmacology by providing insights into cellular responses to pathogens, drugs, and other stimuli. This page compiles peer-reviewed research studies and scholarly articles that explore various in vitro methodologies and their applications in equine science, including cell culture techniques, molecular assays, and drug efficacy testing.
General method for the detection and in vitro expansion of equine cytolytic T lymphocytes.
Journal of immunological methods    July 22, 1998   Volume 213, Issue 1 73-85 doi: 10.1016/s0022-1759(98)00024-6
Hammond SA, Issel CJ, Montelaro RC.Equine immunological research is hindered by the lack of a simple yet reliable general protocol by which to assay CTL activity specific for viral or parasitic antigens. We present here the first comprehensive analysis of the parameters necessary to reliably culture equine T cells and to analyze the antigen specific cytolytic activity of T lymphocytes utilizing the equine infectious anemia virus (EIAV) infection of outbred ponies as a source for in vivo primed T lymphocytes. Effective long-term in vitro culture of equine T cells was determined to require minimally 200 U/ml of recombinant human ...
Endometrial connexin expression in the mare and pig: evidence for the suppression of cell-cell communication in uterine luminal epithelium.
The Anatomical record    July 21, 1998   Volume 251, Issue 3 277-285 doi: 10.1002/(SICI)1097-0185(199807)251:3<277::AID-AR1>3.0.CO;2-T
Day WE, Bowen JA, Barhoumi R, Bazer FW, Burghardt RC.This investigation examines the relationship between implantation strategy and gap junction protein expression in uterine endometrium. The pattern of gap junction and connexin protein expression was analyzed in porcine and equine endometrium from cycling and pregnant animals using electron microscopy and immunocytochemistry. Functional analysis of cell-cell communication was also monitored by laser cytometry in primary cultures of endometrial epithelial cells. Gap junctions were detected in endometrial stroma of cycling and pregnant animals, which was correlated with immunoreactive Cx43 within...
Maturation-promoting factor (MPF) and mitogen activated protein kinase (MAPK) expression in relation to oocyte competence for in-vitro maturation in the mare.
Molecular human reproduction    July 17, 1998   Volume 4, Issue 6 563-570 doi: 10.1093/molehr/4.6.563
Goudet G, Belin F, Bézard J, Gérard N.In the equine species, a large proportion of oocytes fail to complete meiosis during in-vitro culture. The biochemical and molecular basis of this failure is unknown. The meiotic cell cycle is controlled in part by the maturation-promoting factor (MPF) and the mitogen-activated protein kinase (MAPK). In this study, we evaluated the oocyte competence for in-vitro maturation and the expression of MPF components (p34cdc2 and cyclin B) and MAPK after in-vitro culture. The maturation rate was influenced by the culture medium and the physiological stage of the mare at the time of oocyte recovery. We...
Loading-induced changes in synovial fluid affect cartilage metabolism.
British journal of rheumatology    July 17, 1998   Volume 37, Issue 6 671-676 doi: 10.1093/rheumatology/37.6.671
Van den Hoogen BM, van de Lest CH, van Weeren PR, Lafeber FP, Lopes-Cardozo M, van Golde LM, Barneveld A.The purpose of this study was to determine whether changes in the synovial fluid (SF) induced by in vivo loading can induce an alteration in the metabolic activity of chondrocytes in vitro. Therefore, SF was collected from ponies after a period of box rest and after they had exercise for a week. Normal, unloaded articular cartilage explants were cultured in 20% solutions of these SFs for 4 days and chondrocyte activity was determined by glycosaminoglycan (GAG) turnover. In explants cultured in post-exercise SF, GAG synthesis was enhanced and GAG release was diminished when compared to cultures...
Influence of exogenous hyaluronan on synthesis of hyaluronan and collagenase by equine synoviocytes.
American journal of veterinary research    July 11, 1998   Volume 59, Issue 7 888-892 
Lynch TM, Caron JP, Arnoczky SP, Lloyd JW, Stick JA, Render JA.To evaluate the influence of exogenous hyaluronan (HA) on in vitro synthesis of HA and collagenase by equine synoviocytes from normal and inflamed joints. Methods: 9 adult horses. Methods: Synoviocytes for culture were taken from the middle carpal joint of 3 horses with normal joints (control) and 6 horses with osteochondral fractures (principal). Synoviocytes were propagated in monolayer cultures and were incubated with 3 commercial HA products at concentrations of 0, 200, 400, and 1,500 micrograms/ml. Newly synthesized HA was radiolabeled with [3H]glucosamine and quantified by cetylpyridiniu...
Monoclonal antibody against Babesia equi: characterization and potential application of antigen for serodiagnosis.
Journal of clinical microbiology    July 3, 1998   Volume 36, Issue 7 1835-1839 doi: 10.1128/JCM.36.7.1835-1839.1998
Avarzed A, Igarashi I, De Waal DT, Kawai S, Oomori Y, Inoue N, Maki Y, Omata Y, Saito A, Nagasawa H, Toyoda Y, Suzuki N.Monoclonal antibody (MAb) BEG3 was produced against Babesia equi parasites to define a species-specific antigen for diagnostic use. The MAb reacted with single, paired, and Maltese cross forms of B. equi, and no reaction was observed with this MAb on acetone-fixed Babesia caballi, Babesia ovata, or Babesia microti parasites in the indirect immunofluorescent antibody test. Confocal laser and immunoelectron microscopic studies showed that the antigen which was recognized by this MAb was located on the surface of B. equi parasites. This MAb recognized a 19-kDa protein of B. equi antigen and did n...
Determination of the volume changes for pressure-induced transitions of apomyoglobin between the native, molten globule, and unfolded states.
Biophysical journal    July 2, 1998   Volume 75, Issue 1 463-470 doi: 10.1016/S0006-3495(98)77534-4
Vidugiris GJ, Royer CA.The volume change for the transition from the native state of horse heart apomyoglobin to a pressure-induced intermediate with fluorescence properties similar to those of the well-established molten globule or I form was measured to be -70 ml/mol. Complete unfolding of the protein by pressure at pH 4.2 revealed an upper limit for the unfolding of the intermediate of -61 ml/mol. At 0.3 M guanidine hydrochloride, the entire transition from native to molten globule to unfolded state was observed in the available pressure range below 2.5 kbar. The volume change for the N-->I transition is relat...
Direct sequencing of the HA gene of clinical equine H3N8 influenza virus and comparison with laboratory derived viruses.
Archives of virology    June 30, 1998   Volume 143, Issue 5 891-901 doi: 10.1007/s007050050340
Ilobi CP, Nicolson C, Taylor J, Mumford JA, Wood JM, Robertson JS.Equine influenza viruses propagated in the laboratory in alternate hosts such as embryonated hens' eggs or mammalian cell culture have been analysed by HA sequencing and antigenically and their sequence compared to the original virus present in clinical material. In contrast to clinically derived human influenza virus which generally grows in MDCK cells without change, the data for equine influenza virus were less clear in that variants of equine virus were derived in both eggs and cells. The study indicated that the current use of eggs for equine influenza virus surveillance and vaccine produ...
Dung-derived biological agents associated with reduced numbers of infective larvae of equine strongyles in faecal cultures.
Journal of helminthology    June 26, 1998   Volume 72, Issue 1 21-26 doi: 10.1017/s0022149x00000924
Bird J, Larsen M, Nansen P, Kraglund HO, Grønvold J, Henriksen SA, Wolstrup J.Two sets of dung-derived organisms from soil routinely fertilized with manure (MA) and soil chemically fertilized (CH) were cultured separately in the laboratory. Baermannized organisms from these cultures were added to 20 g of faeces from strongyle-infected horses to form three treatment groups: (i) no soil organisms; (ii) low inoculum of soil organisms containing all organisms present in a suspension of approximately 100 adult female free-living nematodes; and (iii) high inoculum containing those soil organisms present with approximately 1000 adult female free-living nematodes. Three studies...
Monoclonal antibodies to subclass-specific antigenic determinants on equine immunoglobulin gamma chains and their characterization.
Veterinary immunology and immunopathology    June 25, 1998   Volume 62, Issue 2 153-165 doi: 10.1016/s0165-2427(97)00162-1
Sheoran AS, Lunn DP, Holmes MA.This paper describes the production of a panel of monoclonal antibodies (mAbs) identifying the four recognised equine IgG subisotypes IgG, IgGa, IgGb, IgGc and IgG(T). Pure preparations of the subisotypes for use in immunisations and testing were produced using a combination of gel filtration, salt precipitation, ion exchange chromatography and protein A and Protein G affinity chromatography. The specificity of mAbs for the IgG subisotypes was confirmed using ELISA assays, by characterisation of affinity purified proteins recognised by the mAbs, and by Western blotting of equine serum proteins...
Multiple kinetic intermediates accumulate during the unfolding of horse cytochrome c in the oxidized state.
Biochemistry    June 24, 1998   Volume 37, Issue 25 9147-9155 doi: 10.1021/bi980470u
Bhuyan AK, Udgaonkar JB.The unfolding kinetics of horse cytochrome c in the oxidized state has been studied at 10, 22, and 34 degreesC as a function of guanidine hydrochloride (GdnHCl) concentration. Rapid (millisecond) measurements of far-UV circular dichroism (CD) as well as fluorescence quenching due to tryptophan to heme excitation energy transfer have been used to monitor the unfolding process. At 10 degreesC, the decrease in far-UV CD signal that accompanies unfolding occurs in two phases. The unobservable burst phase is complete within 4 ms, while the slower phase occurs over tens to hundreds of milliseconds. ...
Equine monocyte-derived macrophage cultures and their applications for infectivity and neutralization studies of equine infectious anemia virus.
Journal of virological methods    June 17, 1998   Volume 71, Issue 1 87-104 doi: 10.1016/s0166-0934(97)00204-8
Raabe MR, Issel CJ, Montelaro RC.Equine infectious anemia virus (EIAV) has been shown to infect cells of monocyte/macrophage lineage. These primary cells are intrinsically difficult to obtain, to purify and to culture in vitro for extended periods of time. As a result, most in vitro studies concerning this lentivirus make use of primary equine fibroblasts or transformed canine or feline cell lines. We describe methods that yield reproducibly pure cultures of equine blood monocytes from peripheral blood mononuclear cells. The in vitro differentiation of these cells into mature equine macrophage was verified using various cytoc...
Evidence of new cadmium binding sites in recombinant horse L-chain ferritin by anomalous Fourier difference map calculation.
Proteins    June 17, 1998   Volume 31, Issue 4 477-485 
Granier T, Comberton G, Gallois B, d'Estaintot BL, Dautant A, Crichton RR, Précigoux G.We refined the structure of the tetragonal form of recombinant horse L-chain apoferritin to 2.0 A and we compared it with that of the cubic form previously refined to the same resolution. The major differences between the two structures concern the cadmium ions bound to the residues E130 at the threefold axes of the molecule. Taking advantage of the significant anomalous signal (f" = 3.6 e-) of cadmium at 1.375 A, the wavelength used here, we performed anomalous Fourier difference maps with the refined model phases. These maps reveal the positions of anomalous scatterers at different locations...
Pharmacokinetics and pharmacodynamics of fenleuton, a 5-lipoxygenase inhibitor, in ponies.
Research in veterinary science    June 13, 1998   Volume 64, Issue 2 111-117 doi: 10.1016/s0034-5288(98)90005-4
Marr K, Marsh K, Hernandez L, Cunningham FM, Lees P.Leukotrienes, products of the 5-lipoxygenase pathway of arachidonic acid metabolism, possess properties consistent with their involvement in a range of inflammatory diseases. In this study the pharmacokinetics and pharmacodynamics of the selective 5-lipoxygenase inhibitor, fenleuton, have been examined in the horse. Orally administered fenleuton (four 5 mg kg(-1) doses, given once daily) was absorbed from the gastrointestinal tract, and penetrated readily into tissue cage exudate, the ratio of the plasma:exudate AUC0-48h being 0.90+/-0.02 (n=6). Ionophore-stimulated leukotriene (LT) B4 synthes...
CLoning of equine interleukin 1 alpha and equine interleukin 1 beta and determination of their full-length cDNA sequences.
American journal of veterinary research    June 12, 1998   Volume 59, Issue 6 704-711 
Howard RD, McIlwraith CW, Trotter GW, Nyborg JK.To clone equine interleukin 1 alpha (IL-1 alpha) and equine interleukin 1 beta (IL-1 beta) and determine their full-length cDNA sequences. Methods: The mRNA isolated from lipopolysaccharide-stimulated cultured equine monocytes was reverse transcribed, and a cDNA library was constructed in a lambda phage. The cDNA library was screened by means of plaque hybridization with radiolabeled human IL-1 alpha and IL-1 beta cDNA probes. The cDNA nucleotide sequences for equine IL-1 alpha and equine IL-1 beta were determined by use of the dideoxy chain termination technique. The cDNA sequences were analy...
Effect of tumor necrosis factor antibody given to horses during early experimentally induced endotoxemia.
American journal of veterinary research    June 12, 1998   Volume 59, Issue 6 792-797 
Barton MH, Bruce EH, Moore JN, Norton N, Anders B, Morris DD.To test efficacy of murine monoclonal, rabbit polyclonal recombinant equine or human tumor necrosis factor-alpha (rETNF or rHTNF, respectively) antibodies to inhibit native equine tumor necrosis factor (TNF) activity. Methods: 8 and 18 healthy adult horses for parts 1 and 2 of the study, respectively. Methods: In part 1, supernates from endotoxin-activated peritoneal macrophages were incubated with various dilutions of each rETNF antibody and subsequently tested for TNF activity. Serum was also obtained from a horse 1 hour after infusion with 20 ng of endotoxin/kg of body weight and was incuba...
Equine Embryo Transfer IV. Proceedings of the 4th International Symposium on Equine Embryo Transfer. Reims, France, 16-18 January 1997.
Equine veterinary journal. Supplement    June 6, 1998   Issue 25 6-112 
No abstract available
A conserved structural element in horse and mouse IGF2 genes binds a methylation sensitive factor.
Nucleic acids research    May 30, 1998   Volume 26, Issue 7 1605-1612 doi: 10.1093/nar/26.7.1605
Otte K, Choudhury D, Charalambous M, Engström W, Rozell B.The equine IGF2 gene has been cloned and characterised. It spans a 9 kb region, which is substantially less than the corresponding human gene. Three coding exons and three untranslated leader exons, all highly homologous to those in other species, were identified. Downstream of the polyadenylation site in exon 6, a dinucleotide repeat sequence was identified. Three putative promoters (P1-P3) were localised in the 5' region of the gene. RNase protection analysis revealed two active promoters in fetal tissues, P2 and P3, whereas P3 was the only promoter active in adult tissues. This represents a...
Equine infectious anemia virus transactivator is a homeodomain-type protein.
Journal of molecular biology    May 30, 1998   Volume 277, Issue 4 749-755 doi: 10.1006/jmbi.1998.1636
Willbold D, Metzger AU, Sticht H, Gallert KC, Voit R, Dank N, Bayer P, Krauss G, Goody RS, Rösch P.Lentiviral transactivator (Tat) proteins are essential for viral replication. Tat proteins of human immunodeficiency virus type 1 and bovine immunodeficiency virus form complexes with their respective RNA targets (Tat responsive element, TAR), and specific binding of the equine anemia virus (EIAV) Tat protein to a target TAR RNA is suggested by mutational analysis of the TAR RNA. Structural data on equine infectious anemia virus Tat protein reveal a helix-loop-helix-turn-helix limit structure very similar to homeobox domains that are known to bind specifically to DNA. Here we report results of...
Contribution of K+ channels and ouabain-sensitive mechanisms to the endothelium-dependent relaxations of horse penile small arteries.
British journal of pharmacology    May 30, 1998   Volume 123, Issue 8 1609-1620 doi: 10.1038/sj.bjp.0701780
Prieto D, Simonsen U, Hernández M, García-Sacristán A.1. Penile small arteries (effective internal lumen diameter of 300 600 microm) were isolated from the horse corpus cavernosum and mounted in microvascular myographs in order to investigate the mechanisms underlying the endothelium-dependent relaxations to acetylcholine (ACh) and bradykinin (BK). 2. In arteries preconstricted with the thromboxane analogue U46619 (3-30 nM), ACh and BK elicited concentration-dependent relaxations, pD2 and maximal responses being 7.71+/-0.09 and 91+/-1 % (n=23), and 8.80+/-0.07 and 89+/-2% (n=24) for ACh and BK, respectively. These relaxations were abolished by me...
Peculiarities of vitamin D and of the calcium and phosphate homeostatic system in horses.
Veterinary research    May 28, 1998   Volume 29, Issue 2 173-186 
Breidenbach A, Schlumbohm C, Harmeyer J.The aim of the present study was to investigate the importance of putative regulatory factors of the calcium (Ca) and inorganic phosphate (P(i)) homeostatic system in the horse. The concentrations of Ca, P(i), vitamin D metabolites, parathyroid hormone (PTH), the activity of the alkaline phosphatase (AP) and the concentration and binding properties of vitamin D binding protein (DBP) were measured in the plasma. In addition, the ability of the renal cortex to hydroxylate calcidiol into 24,25(OH)2D3 and 1,25(OH)2D3 was evaluated in vitro. The plasma concentration of Ca (3.2 +/- 0.15 mmol.L-1, N ...
The effect of propanediol on the morphology of fresh and frozen equine embryos.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 80-84 doi: 10.1111/j.2042-3306.1997.tb05107.x
Bruyas JF, Martins-Ferreira C, Fiéni F, Tainturier D.Seventeen horse embryos recovered on the sixth day after spontaneous ovulation were; 1) washed in PBS (n = 6), 2) treated with 1.5 M 1-2 propanediol (n = 6) or, 3) frozen and thawed using 1.5 M propanediol as the cryoprotectant (n = 5). After treatment, the embryos were incubated for 6 h in medium before they were fixed, serially sectioned and examined microscopically to count the total numbers of interphase, mitotic and pycnotic nuclei. Significant differences were measured only in the mean proportions of pycnotic cells (+/- s.d.), both between the control (9.2 +/- 7.3%) and frozen-thawed emb...
Cumulus expansion, chromatin configuration and meiotic competence in horse oocytes: a new hypothesis.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 43-46 doi: 10.1111/j.2042-3306.1997.tb05098.x
Hinrichs K.When recovered from the follicle, horse oocytes may be categorised as having either a compact or an expanded cumulus. Cumulus expansion is strongly associated with follicle atresia. Oocytes with expanded and compact cumuli have similar proportions in the germinal vesicle stage when recovered from the follicle. However, during in vitro culture, a higher proportion of oocytes with expanded cumuli mature, and they do so more quickly, than do oocytes with compact cumuli. Using Hoechst 33258 to label chromatin, in the germinal-vesicle stage horse oocytes can be divided into those in which the nucle...
Treatment of equine oocytes with A23187 after intracytoplasmic sperm injection.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 51-53 doi: 10.1111/j.2042-3306.1997.tb05100.x
Kato H, Seidel GE, Squires EL, Wilson JM.In vitro matured horse oocytes with a first polar body (n = 68) were each injected with a single spermatozoon and divided into 2 groups: Group 1 oocytes were treated with 10 microM calcium ionophore A23187 for 5 min while Group 2 oocytes received no activation treatment. After culture in vitro for 2 days, significantly more oocytes treated with A23187 (5/24, 21%) cleaved than oocytes without activation treatment (2/44, 5%, P<0.05). All 7 cleaved zygotes from both treatment groups were transferred to recipient mares but no pregnancies resulted.
The effect of sucrose in the thawing solution on the morphology and mobility of frozen equine embryos.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 94-97 doi: 10.1111/j.2042-3306.1997.tb05110.x
Huhtinen M, Lagneaux D, Koskinen E, Palmer E.Seventy-five embryos were collected 6 days after ovulation. Sixty embryos were frozen in straws using glycerol as the cryoprotectant in an automatic freezer. In Experiment 1 the freezing and thawing media were supplemented with 1.3 g/l PVP; in Experiment 2 the supplement was 5% FCS. The embryos were thawed for 30 s at +37 degrees C in a waterbath. In Experiment 1 glycerol was removed from 10 embryos in 6 steps. In 10 other embryos, glycerol and sucrose were both removed from the medium in 6 steps. After glycerol and sucrose removal, the embryos were stained with 4',6'-diamidino-2-phenylindole ...
Transfer of immature oocytes to a preovulatory follicle: an alternative to in vitro maturation in the mare?
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 54-59 doi: 10.1111/j.2042-3306.1997.tb05101.x
Goudet G, Bézard J, Duchamp G, Palmer E.In the mare, success rates for the in vitro maturation of oocytes are low. Accordingly, we attempted to determine if immature oocytes could be matured in vivo by injecting them into a preovulatory follicle. Groups of 3-9 oocytes collected from donor mares were transferred under ultrasound control into the preovulatory follicle of a recipient mare that was treated with crude equine pituitary gonadotrophin (CEG) to induce ovulation. Just before ovulation (34 h post treatment) the preovulatory follicle of the recipient mare was punctured to collect both the transferred and the indigenous oocytes ...
Cryopreservation procedures for Day 7-8 equine embryos.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 98-102 doi: 10.1111/j.2042-3306.1997.tb05111.x
Young CA, Squires EL, Seidel GE, Kato H, McCue PM.Larger grade 1 or 2 (1 = excellent,.... 4 = degenerate) equine embryos that ranged in diameter from 300 to 680 microm and were recovered from mares on Day 7 or 8 after ovulation, were randomly assigned to 3 widely divergent cryopreservation treatments. Treatment 1 consisted of cooling from -6 degrees C to -35 degrees C at 0.5 degrees C per min followed by plunging into liquid nitrogen, with a one-step addition and a 4-step removal of 1.0 M glycerol. Treatment 2 (step-down equilibration) consisted of a 2-step addition of glycerol to 4.0 M followed by a decrease to 2.0 M prior to freezing, with ...
Cryopreservation of equine embryos with glycerol plus sucrose and glycerol plus 1,2-propanediol.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 88-93 doi: 10.1111/j.2042-3306.1997.tb05109.x
Ferreira JC, Meira C, Papa FO, Landin e Alvarenga FC, Alvarenga MA, Buratini J.Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were remov...
Comparison of different methods for the recovery of horse oocytes.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 47-50 doi: 10.1111/j.2042-3306.1997.tb05099.x
Alm H, Torner H, Kanitz W, Becker F, Hinrichs K.The object of this study was to compare 4 different methods of oocyte recovery from mares; 1) transvaginal follicle aspiration in vivo; 2) follicle aspiration in vitro; 3) oocyte recovery by isolation of follicles in vitro and 4) follicle scraping in vitro. Oocyte recovery was highest after follicle scraping (71.1%) and follicle isolation and rupture (61.3%). Follicle aspiration in vitro and in vivo yielded oocytes on 31.2% and 19.3% of occasions, respectively. The output of different types of cumulus-oocyte-complexes was different among the methods; the portion of compact cumulus-oocyte-compl...
Timing of in vivo maturation of equine preovulatory oocytes and competence for in vitro maturation of immature oocytes collected simultaneously.
Equine veterinary journal. Supplement    May 21, 1998   Issue 25 33-37 
Bézard J, Mekarska A, Goudet G, Duchamp G, Palmer E.The objects of this study were to monitor the development of the cumulus complex and nuclear maturation in oocytes recovered from preovulatory follicles following treatment to induce ovulation and to investigate the in vitro maturation competence of oocytes recovered from smaller nonpreovulatory follicles of varying size. All follicles > or =5 mm in pony mares were individually punctured at 0, 6, 12, 24 and 35 h after an injection of LH to induce ovulation. The recovery rates of oocytes were 64% from 55 preovulatory follicles, 22% from 32 subordinate follicles and 52% from 227 small follicl...