Ovarian follicles in horses are structures within the ovaries that contain the developing oocyte, or egg, and are essential for reproduction. These follicles undergo a series of growth stages, from primordial to preovulatory, influenced by hormonal changes within the mare's reproductive cycle. The development and maturation of ovarian follicles are regulated by hormones such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Monitoring follicular development is integral to understanding reproductive physiology and managing breeding in equine practice. This page compiles peer-reviewed research studies and scholarly articles that explore the physiology, development, and clinical management of ovarian follicles in horses.
Galli C, Duchi R, Colleoni S, Lagutina I, Lazzari G.Assisted reproductive techniques developed for cattle in the last 25 years, like ovum pick up (OPU), intracytoplasmic sperm injection (ICSI), and somatic cell nuclear transfer, have been transferred and adapted to buffalo and horses. The successful clinical applications of these techniques require both the clinical skills specific to each animal species and an experienced laboratory team to support the in vitro phase of the work. In cattle, OPU can be considered a consolidated technology that is rapidly outpacing conventional superovulation for embryo transfer. In buffalo, OPU represents the ...
Leonel EC, Bento-Silva V, Ambrozio KS, Luna HS, Costa e Silva EV, Zúccari CE.The aim of this study was to test the use of mechanical and mechanical-enzymatic methods, saline solution (SS), and PBS solution for the manipulation and isolation of mare ovarian preantral follicles (PAFs). The ovaries were subjected to mechanical isolation (mixer) alone or in association with enzymatic digestion (collagenase). Incubation times of 10 and 20 min were employed. In the first group, 4.1 ± 4.9 PAFs were harvested with the mechanical-enzymatic method vs 71.1 ± 19.2 with the mechanical procedure, showing a significant difference between methods; using SS and PBS, these number...
Schauer SN, Sontakke SD, Watson ED, Esteves CL, Donadeu FX.Previous evidence from in vitro studies suggests specific roles for a subset of miRNAs, including miR-21, miR-23a, miR-145, miR-503, miR-224, miR-383, miR-378, miR-132, and miR-212, in regulating ovarian follicle development. The objective of this study was to determine changes in the levels of these miRNAs in relation to follicle selection, maturation, and ovulation in the monovular equine ovary. In Experiment 1, follicular fluid was aspirated during ovulatory cycles from the dominant (DO) and largest subordinate (S) follicles of an ovulatory wave and the dominant (DA) follicle of a mid-cycle...
Donadeu FX, Schauer SN.Relatively little is known about the physiological roles of microRNAs (miRNAs) during follicular development. Previous evidence from in vitro studies suggests specific roles for a subset of miRNAs, including miR-21, miR-23a, miR-145, miR-503, miR-224, miR-383, miR-378, miR-132, and miR-212, in regulating ovarian follicle development. The objective of this study was to gain insight on the involvement of these miRNAs during follicle maturation. Follicular fluid was aspirated from dominant follicles (>32 mm) during the ovulatory season (July to October) and the anovulatory season (January to M...
Pereira GR, Lorenzo PL, Carneiro GF, Ball BA, Bilodeau-Goeseels S, Kastelic J, Pegoraro LM, Pimentel CA, Esteller-Vico A, Illera JC, Granado GS....The objectives of this study were to evaluate the effects of equine growth hormone (eGH) on nuclear and cytoplasmic maturation of equine oocytes in vitro, steroid production by cumulus cells, and expression and subcellular localization of eGH-receptors (eGH-R) on equine ovarian follicles. Cumulus-oocyte complexes (COCs) were recovered by aspirating follicles <30 mm in diameter from abattoir-derived ovaries. The COCs were morphologically evaluated and randomly allocated to be cultured in either a control maturation medium or supplemented with 400 ng/mL eGH, for 30 h at 38.5°C in air with 5%...
Cavalleri JM, Bienert-Zeit A, Feige K.The article summarizes the relevant clinical pathological assessment of horses with acute colic. A minimal laboratory evaluation should include the patient's haematocrit (or packed cell volume), total protein, and lactate concentration in the blood. Haematocrit and total protein provide an indication of the severity of dehydration (haematocrit < 0.45 l/l is evidence of no to mild dehydration whereas > 0.5 l/l points to a severe dehydration). The degree of dehydration is often associated with the severity of the colic. Additionally, the blood lactate concentration rises with increasing intesti...
Binder AK, Rodriguez KF, Hamilton KJ, Stockton PS, Reed CE, Korach KS.Determining the spatial and temporal expression of genes involved in the ovulatory pathway is critical for the understanding of the role of each estrogen receptor in the modulation of folliculogenesis and ovulation. Estrogen receptor (ER)-β is highly expressed in ovarian granulosa cells, and mice lacking ER-β are subfertile due to inefficient ovulation. Previous work has focused on isolated granulosa cells or cultured follicles and, although informative, provides confounding results due to the heterogeneous cell types present including granulosa and theca cells and oocytes and exposure to in...
Caron JP.Laparoscopic removal of the gonads from male and female horses is regularly performed for a variety of reasons. In female horses, common indications for ovariectomy include behavioral problems and signs of abdominal pain that are linked to estrus. Another indication is an abnormal, enlarged ovary, typically due to ovarian neoplasia, the most common being granulosa thecal cell tumor. Ovariectomy is also a treatment option for ovarian hematomas and other abnormalities. In addition, ovariectomy is used to sterilize mares intended for artificial insemination or embryo transfer programs.
Kelley DE, Warren LK, Mortensen CJ.L-arginine is an amino acid which can alter pituitary function and increase blood flow to the reproductive tract. The objective was to determine the effect of supplementing 100g of L-arginine on plasma arginine concentrations, follicular dynamics and ovarian and uterine artery blood flow during the estrus that occurs subsequent to foaling. In Experiment 1, mares were fed 100g L-arginine for 1 day during the last 3 weeks of pregnancy and plasma samples taken for every hour for the first 4h and every other hour until 12h.L-arginine supplementation elevated plasma arginine concentrations from 1 t...
Newcombe JR, Cuervo-Arango J.It is believed that during the spring transition, the developing follicle tends to grow more slowly, persist longer and grow to a larger diameter prior to ovulation than at subsequent oestrus periods. A general suspicion, that the first ovulation of the year is less fertile than subsequent ovulations could be explained by a slower growth rate of the ovulatory follicle during transition with the consequent production of a subfertile oocyte. By detailed serial examination of the same group of Irish Draught mares over three winter/spring periods, no significant difference was found in either grow...
Haag KT, Magalhães-Padilha DM, Fonseca GR, Wischral A, Gastal MO, King SS, Jones KL, Figueiredo JR, Gastal EL.The objective was to conduct a preliminary evaluation of the efficacy of two media for in vitro culture of equine preantral follicles. Ovarian cortical strips were obtained from mares (N = 10) via the Biopsy Pick-Up method during the breeding season. Ovarian tissue was immediately submitted to histological analysis (noncultured control; D0) or cultured in situ for 1 day (D1) or 7 days (D7) in either α-MEM or TCM-199 and submitted to histological analysis, generating five treatment groups: noncultured control, α-MEM:D1, TCM-199:D1, α-MEM:D7, and TCM-199:D7. Preantral follicles were evaluated...
Haag KT, Magalhães-Padilha DM, Fonseca GR, Wischral A, Gastal MO, King SS, Jones KL, Figueiredo JR, Gastal EL.The aims of this study in mares were to: (1) compare preantral follicle parameters between in vitro Biopsy Pick-Up (BPU) and scalpel blade collection methods and between histological and mechanical isolation processing (experiment 1); (2) histologically evaluate preantral follicles (experiment 2); and (3) compare histological analysis with a previously established mechanical isolation technique using a tissue chopper (experiment 3) for ovarian cortical fragments obtained in vivo using a BPU instrument. In experiment 1, preantral follicles were analyzed (N = 220; 90% primordial and 10% primary)...
Ignácio FS, Bergfelt DR, Mendes D, Orlandi C, Araújo GH, Oliveira JV, Montechiesi DF, Carvalho LR, Meira C.The primary objective of this study was to examine the follicular and ovulatory responses following treatment with pFSH in association with ablation-induced or spontaneous follicular wave emergence or follicle deviation during diestrus in crossbred (Mangalarga×Arabian) and Brazilian Warmblood mares with a propensity for spontaneous multiple ovulations; secondary considerations were given to the collection of embryos. In Experiment 1, crossbred mares were administered (im) saline (control, n=7) or pFSH (25mg) when the largest follicle of the ablation-induced follicular wave reached ≥13mm (n=...
Haag KT, Magalhães-Padilha DM, Fonseca GR, Wischral A, Gastal MO, King SS, Jones KL, Figueiredo JR, Gastal EL.A Biopsy Pick-Up (BPU) method was tested to determine the feasibility of retrieving preantral follicles from mare ovaries in vivo. A total of 33 ovarian biopsy procedures were performed on 18 mares during the breeding season. Mares were 5 to 21 years old and biopsies were performed during the estrous and/or diestrous phase, as confirmed by transrectal ultrasonography. Follicles were mechanically isolated using a tissue chopper, counted, and classified as normal or abnormal and primordial or primary. Viability of isolated follicles was determined by Trypan Blue dye. A total of 256 biopsy attemp...
Schauer SN, Guillaume D, Decourt C, Watson ED, Briant C, Donadeu FX.There is evidence in several species that high circulating LH concentrations can interfere with normal follicle development and ovulation. In the mare, high LH levels after induction of luteolysis with PGF(2α) have been temporally associated with an increased incidence of anovulatory follicles. We hypothesized that a premature increase in LH levels during a follicular wave in mares would disrupt normal follicle maturation leading to ovulatory dysfunction. In experiment 1, all follicles >10 mm were ablated at midestrous cycle in pony mares followed by twice daily administration of equine LH...
Mata F.Several growth models are commonly used in the biological sciences, to model the follicle growth occurring in the estrous cycle. The aim of this project was to find the model that best fit the follicular size growth data for Lusitano mares. Retrospective data collected from reproduction book records of n=84 mares and n=124 cycles was used to find the series to be fitted to the models. The exponential, Gompertz, logistic, von Bertalanffy, Richards and Weibull models were used, and the most parsimonious and best fit was achieved with the logistic model (r(2)=0.999). The logistic model fits the L...
Galvão A, Valente L, Skarzynski DJ, Szóstek A, Piotrowska-Tomala K, Rebordão MR, Mateus L, Ferreira-Dias G.Regulation of immune-endocrine interactions in the equine endometrium is not fully understood. The aims of the present study were to: (1) investigate the presence of tumour necrosis factor alpha (TNF), interferon gamma (IFNG), Fas ligand (FASLG) and their receptors in the mare endometrium throughout the oestrous cycle; and (2) assess endometrial secretory function (prostaglandins), angiogenic activity and cell viability in response to TNF, oestradiol (E2), progesterone (P4) and oxytocin (OXT). Transcription of TNF and FASLG mRNA increased during the early and late luteal phase (LP), whereas IF...
Lange-Consiglio A, Arrighi S, Fiandanese N, Pocar P, Aralla M, Bosi G, Borromeo V, Berrini A, Meucci A, Dell'Aquila ME, Cremonesi F.There is no published information about follicular-fluid leptin concentrations or the presence of leptin and leptin receptor in the equine ovary or oocyte. Three groups of mares - adult draft mares, draft fillies and adult Standardbred mares - were included in the study. Leptin and leptin receptor were detected in all immature oocytes by immunofluorescence with higher intensity in oocytes from draft mares compared with draft fillies and Standardbred mares. After in vitro maturation a higher proportion of oocytes reached metaphase II in draft mares than in draft fillies and Standardbred mares, ...
Ababneh MM, Troedsson MH.Real-time PCR was used to investigate the role of progesterone (P4) and oestradiol (E2) in regulation of endometrial cytosolic, secretory and calcium-independent phospholipase A2 (PLA2G4A, PLA2G2A and PLA2G6, respectively) gene expression. Ovariectomized mares underwent 6 days of E2 pre-treatment followed by 14 days of P4 supplementation. At the start of P4 treatment (Day 1), mares were assigned in a 2 × 2 factorial design to receive either E2 or vehicle starting on Day 11 and endometrial biopsy collection on either Day 14 when P4 concentrations remained high (>4 ng/ml) or Day 16 when P4 conc...
Pinaffi FL, Khan FA, Silva LA, Beg MA, Ginther OJ.The effects of a PRL-stimulating substance (sulpiride) on PRL and PGF2α secretion and on luteal and ovarian follicular dynamics were studied during the estrous cycle in mares. A control group (n = 9) and a sulpiride group (Sp; n = 10) were used. Sulpiride (25 mg) was given every 8 h from Day 13 postovulation to the next ovulation. Repeated sulpiride treatment did not appear to maintain PRL concentrations at 12-h intervals beyond Day 14. Therefore, the hypothesis that a long-term increase in PRL altered luteal and follicular end points was not testable. Hourly samples were collected from the h...
Altermatt JL, Marolf AJ, Wrigley RH, Carnevale EM.Objectives of the experiment were to determine the effects of mare age and gonadotropin treatments on dominant follicle vascularity, ovarian blood flow and dominant follicle growth and to associate follicular vascularity with oocyte developmental capacity. Growing follicles >30 mm from young (4-9 years) and old (>20 years) mares were assessed for blood flow using color Doppler ultrasonography before maturation induction with recombinant equine LH (eLH) and immediately prior to oocyte collection at 20-24 h after eLH. Pulsed Doppler was used to obtain resistance indices of ovarian arteries...
Miro J.Ultrasonography has become indispensable in the control of equine reproduction. Mare ovary layers are inverted with respect to other species, with the follicles and corpus luteum found inside the ovary; only large follicles protrude from the organ's surface. This renders the making of diagnoses via rectal palpation of the ovaries very difficult. Ultrasound imaging, however, provides another avenue of examination. Since its first use in 1980, the diagnostic potential of ultrasonography has greatly improved. Colour Doppler ultrasonography can even asses blood flow, allowing for much better monit...
Smith RL, Vernon KL, Kelley DE, Gibbons JR, Mortensen CJ.The advent of embryo transfer has allowed horses to continue to train and compete during the breeding season. However, the associated stress of exercise may be detrimental to reproduction. The objectives of this study were to evaluate differing exercise protocols on reproductive blood flow and embryonic outcomes in mares. Light-horse mares were randomized into control (n = 4), partial-exercised (n = 6), and full-exercised (n = 6) groups. Partial-exercised mares were moderately exercised 30 min daily during the periovulatory period and rested after ovulation for 7 d. Full-exercised mares were e...
Gomes RG, Andrade ER, Lisboa LA, Ciquini A, Barreiros TR, Fonseca NA, Seneda MM.The objective was to evaluate the efficiency of phosphate-buffered saline (PBS) and Minimum Essential Medium (MEM) during the transport of equine preantral and antral follicles at various temperatures and incubation interval. Equine ovaries (n = 10) from an abattoir were cut into 19 fragments; one was immediately fixed in Bouin's solution (control) and the other fragments were placed in PBS or MEM solution at 4, 20, or 39 °C for 4, 12, or 24 h. After the respective incubation periods, all fragments were fixed in Bouin's solution for 24 h and then submitted to standard histologic analysis. In ...
Tate LP, Fogle CA, Bailey CS, Tate KB, Davis JW.To describe a technique for ovariectomy through a colpotomy using a chain écraseur with laparoscopic guidance and report outcome in 4 mares. Methods: Case series. Methods: After insertion of a laparoscope into the abdomen through the left flank, colpotomy was performed to allow introduction of an écraseur into the caudal aspect of the abdomen. Grasping and removal of the ovary and evaluation of the pedicle was observed via the laparoscope. The laparoscope was then inserted in the right flank for right ovariectomy. The colpotomy was closed in a continuous suture pattern using laparoscopic or ...
Schulman ML, Botha AE, Muenscher SB, Annandale CH, Guthrie AJ, Bertschinger HJ.Active immunisation against gonadotrophin-releasing hormone (GnRH) provides a reversible method for control of oestrous behaviour and fertility in mares. Previous reports failed to demonstrate the interval to resumption of cyclic ovarian activity after GnRH-vaccination. Objective: Administration of the GnRH-vaccine Improvac in a large group of mares of various ages will result in effective, reliably reversible suppression of ovarian activity within a 2 year period. Methods: The mares, subdivided into 3 age categories, were vaccinated twice (with a 35 day interval) using 400 µg Improvac and mo...
da Silveira JC, Veeramachaneni DN, Winger QA, Carnevale EM, Bouma GJ.Proper cell communication within the ovarian follicle is critical for the growth and maturation of a healthy oocyte that can be fertilized and develop into an embryo. Cell communication within the follicle involves many signaling molecules and is affected by maternal age. Recent studies indicate that cell communication can be mediated through secretion and uptake of small membrane-enclosed vesicles. The goals of this study were to 1) identify cell-secreted vesicles (microvesicles and exosomes) containing miRNAs and proteins within ovarian follicular fluid and 2) determine if miRNA level differ...
Witt MC, Bollwein H, Probst J, Baackmann C, Squires EL, Sieme H.The aim of the present study was to investigate the effects of a gonadotropin treatment to induce superovulation on ovarian and uterine blood flow and its relationship with steroid hormone levels and ovarian response in mares, using color Doppler sonography. Each of six mares were examined sonographically in five cycles for 3 d (t1 to t3) during the follicular development phase (FDP) beginning at a follicle size of ≥ 22 mm, and for 4 d (D-4 to D-1; D0 = Ovulation) in the preovulatory phase (POP). After each examination, total estrogens (E(tot)) and progesterone (P(4)) levels were determined ...
Hanlon DW, Firth EC.The objective of this study was to investigate the effects of intravaginal progesterone on the reproductive performance of transitional Thoroughbred mares on commercial stud farms. Two hundred twenty-seven (227) non-lactating transitional Thoroughbred mares aged between 4 and 18 y (mean 9.4 ± 3.2 y) located on three stud farms in the Waikato region of New Zealand were used in the study performed during four consecutive breeding seasons (2007-10). Mares were age-matched in pairs and either treated with an intravaginal progesterone releasing device (Cue-Mare, 1.72 g progesterone, 10% w/w) for u...
Mattos MC, Bastos MR, Guardieiro MM, Carvalho JO, Franco MM, Mourão GB, Barros CM, Sartori R.The aim of this study was to evaluate the superovulatory (SOV) response of Sindhi (Bos indicus) donors submitted to an ovarian follicular superstimulatory protocol replacing the last two doses of pFSH by eCG. Forty-eight SOV treatments were performed in a crossover design in 19 nulliparous and primiparous females that were randomly divided into two groups: FSH (n=24), which consisted of eight pFSH injections, or FSH/eCG (n=24), which consisted of six pFSH injections followed by two eCG injections. Each female underwent two or three SOV treatments that consisted of an i.m. injection of 2mg estr...
Kelley DE, Warren LK, Mortensen CJ.L-arginine is an amino acid which can alter pituitary function and increase blood flow to the reproductive tract. The objective was to determine the effect of supplementing 100g of L-arginine on plasma arginine concentrations, follicular dynamics and ovarian and uterine artery blood flow during the estrus that occurs subsequent to foaling. In Experiment 1, mares were fed 100g L-arginine for 1 day during the last 3 weeks of pregnancy and plasma samples taken for every hour for the first 4h and every other hour until 12h.L-arginine supplementation elevated plasma arginine concentrations from 1 t...
Ishak GMA, Dutra GA, Gastal GDA, Gastal MO, Feugang JM, Gastal EL.The inability to obtain in vivo samples of antral follicle wall layers without removing the ovaries or sacrificing the animals has limited more in-depth studies on folliculogenesis. In this study, a novel ultrasound-guided follicle wall biopsy (FWB) technique was used to obtain in vivo follicle wall layers and follicular fluid samples of growing antral follicles. The expression of proliferative, hormonal, angiogenic, and pro-/antiapoptotic receptors and proteins in the follicular wall among three follicle classes were compared during the spring transitional anovulatory (SAN) and spring ovulato...
Agnieszka N, Joanna K, Wojciech W, Adam O.The aim of this study was determine the viability and developmental competence of equine oocytes after IVM and vitrification using the Rapid-I method, as part of an effort to develop an effective equine oocyte vitrification protocol. Equine oocytes were collected by scraping ovarian follicles of slaughtered mares. A total of 1052 ovaries were used in this study, from which 3135 oocytes were obtained. Of the 2853 oocytes retrieved, 2557 underwent in vitro maturation for approximately 36 h. After in vitro culture, 1202 oocytes (47%) had a first polar body. To evaluate the toxicity of the solu...
Koskinen E.In a previous study, times from parturition to the first ovulation were followed in 55 Finnhorse mares on the basis of milk progesterone determinations. Ninety-six per cent of mares had ovulated by day 20 post-partum. If intervals of more than 19 days are excluded from the data, the time from parturition to 1st ovulation was 117 days. However, in cases of foaling before and after the beginning of June the times were 13.0 days and 8.8 days, respectively (p less than 0.001). Long intervals (over 16 days) occurred mainly before 1st May (in 6 out of 7 cases). In a 2nd study, 25 post-partum Finnhor...
Marth CD, Young ND, Glenton LY, Noden DM, Browning GF, Krekeler N.The physiological changes associated with the varying hormonal environment throughout the oestrous cycle are linked to the different functions the uterus needs to fulfil. The aim of the present study was to generate global gene expression profiles for the equine uterus during oestrus and Day 5 of dioestrus. To achieve this, samples were collected from five horses during oestrus (follicle >35 mm in diameter) and dioestrus (5 days after ovulation) and analysed using high-throughput RNA sequencing techniques (RNA-Seq). Differentially expressed genes between the two cycle stages were further inves...
Sharp DC, Vernon MW, Zavy MT.Oestrous behaviour, ovarian follicular development, ovulation and changes in hair coat were observed in Pony mares which were unoperated, sham-ganglionectomized control or bilaterally superior cervical ganglionectomized. Surgery was performed during the winter anoestrus (1975--1976). Reproductive patterns in all groups were similar during the first breeding season (1976) after operation but in ganglionectomized mares the onset of the next breeding season (date of first ovulation in 1977), the pattern of follicular development, date of first oestrus and pattern of hair coat changes were all sig...
Altermatt JL, Marolf AJ, Wrigley RH, Carnevale EM.Objectives of the experiment were to determine the effects of mare age and gonadotropin treatments on dominant follicle vascularity, ovarian blood flow and dominant follicle growth and to associate follicular vascularity with oocyte developmental capacity. Growing follicles >30 mm from young (4-9 years) and old (>20 years) mares were assessed for blood flow using color Doppler ultrasonography before maturation induction with recombinant equine LH (eLH) and immediately prior to oocyte collection at 20-24 h after eLH. Pulsed Doppler was used to obtain resistance indices of ovarian arteries...
Asa CS.Behavior during the estrous phase of the ovulatory cycle of the mare is analogous in most ways to that of estrous females of other species. Proceptive behaviors bring the mare into the proximity of the male and attract his attention. Positioning facilitates mounting, intromission, and ejaculation. Estrous signs appear to be more intense in the few days prior to ovulation than during the transition periods that separate the recurring estrous and diestrous phases. Sexual behavior is absent during diestrus. Detection of estrus in mares is problematic in that it requires the presence (or at least ...
Devick IF, Leise BS, McCue PM, Rao S, Hendrickson DA.Determining if ovariectomy will abolish unwanted behaviors can be challenging in mares without ultrasonographic ovarian abnormalities and/or endocrine values not consistent with a granulosa cell tumor. The objective of the study was to identify mares that have a positive improvement in unwanted behaviors after elective standing laparoscopic ovariectomy and to determine if the change is associated with any pre- and post-operative endocrine profiles and/or with ovarian histological findings. During the study period 27 mares underwent a bilateral standing laparoscopic ovariectomy. Pre- and post-o...
Ginther OJ, Gastal EL, Gastal MO, Beg MA.The effect of an injection of a supraphysiologic dose of rhIGF1 into the second-largest ovarian follicle (F2) at the expected beginning of deviation (F1, > or =20 mm; Day 0) on development of dominance by F2 was studied in mares (n=16; controls, n=8). F1 became dominant (> or =28 mm) in 8 of 8 and 15 of 16 follicles in the controls and treated groups, respectively. The incidence of dominance (P<0.001) and ovulation (P or =20mm after the expected beginning of deviation resulted in dominance by 8 of 12 follicles treated with rhIGF1 on Days 1-3 (n=8 mares). Results demonstrated that the ...
Gastal EL, Aguiar FLN, Gastal GDA, Alves KA, Alves BG, Figueiredo JR.The mammalian ovary is responsible for essential stages of folliculogenesis and hormonal production, regulating the female physiological functions during the menstrual/estrous cycles. The mare has been considered an attractive model for comparative studies due to the striking similarities shared with women regarding in vivo and in vitro folliculogenesis. The ovarian follicular population in horses contains a large number of oocytes enclosed in preantral follicles that are yet to be explored. Therefore, the in vitro manipulation of equine preantral follicles aims to avoid the process of atre...
Catalán J, Martínez-Rodero I, Yánez-Ortiz I, Mateo-Otero Y, Bragulat AF, Nolis P, Carluccio A, Yeste M, Miró J.Follicular fluid is formed from the transudation of theca and granulosa cells in the growing follicular antrum. Its main function is to provide an optimal intrafollicular microenvironment to modulate oocyte maturation. The aim of this study was to determine the metabolomic profile of preovulatory follicular fluid (PFF) in jennies. For this purpose, PFF was collected from 10 follicles of five jennies in heat. Then, PFF samples were analysed by nuclear magnetic resonance (NMR) and heteronuclear single quantum correlation (2D H/C HSQC). Our study revealed the presence of at least 27 metabolites i...
Gerstenberg C, Allen WR, Stewart F.Immunohistochemical detection of the proliferation marker Ki-67 antigen was used to monitor mitotic activity in the endometrium of mares. The monoclonal antibody MIB1 was validated for use on equine tissues by demonstrating its reaction with activated peripheral blood lymphocytes, and endometrial biopsies were recovered from 26 non-pregnant mares at selected stages during the reproductive cycle. The proportion of positively stained nuclei was counted in five random areas on each histological section to determine the percentage and type of proliferating cells. Multiplication rates in the types ...
Gastal EL, Kot K, Ginther OJ.A technique for intrafollicular treatment with a transvaginal ultrasound-guided injection needle was developed using equine chorionic gonadotropin (eCG) as the test substance. An injection was made into one growing follicle of a wave when the follicles were 20 to 23 mm. The treated follicles were injected with 1000 iu of eCG in 0.2 ml saline solution and control follicles were injected with 0.2 ml of the saline vehicle (10 mares per group, 1 follicle per mare). The injection system used an inner 25-gauge needle and an outer 20-gauge needle inserted together through the needle-guide channel of ...
Haag KT, Magalhães-Padilha DM, Fonseca GR, Wischral A, Gastal MO, King SS, Jones KL, Figueiredo JR, Gastal EL.The aims of this study in mares were to: (1) compare preantral follicle parameters between in vitro Biopsy Pick-Up (BPU) and scalpel blade collection methods and between histological and mechanical isolation processing (experiment 1); (2) histologically evaluate preantral follicles (experiment 2); and (3) compare histological analysis with a previously established mechanical isolation technique using a tissue chopper (experiment 3) for ovarian cortical fragments obtained in vivo using a BPU instrument. In experiment 1, preantral follicles were analyzed (N = 220; 90% primordial and 10% primary)...
Almadhidi J, Seralini GE, Fresnel J, Silberzahn P, Gaillard JL.Estrogens are the major steroids produced by equine gonads. To identify the cells responsible for estrogen synthesis, an antiserum against purified equine testicular cytochrome P450 aromatase was produced in rabbits. The reactivity and specificity of the antiserum were assessed by ELISA, immunoblot analysis, and immunoneutralization studies. Immunofluorescence microscopy demonstrated that in the male gonad, cytochrome P450 aromatase (P450arom) was localized in the interstitial tissue, whereas, under the experimental conditions used, the Sertoli and germ cells did not show any specific staining...
Gastal EL, Gastal MO, Ginther OJ.A two-follicle model was used to study the nature of selection of the dominant follicle in mares by ablating neither or one of the two follicles on the day the larger follicle reached >/= 20 mm (Day 0). The larger follicle became the dominant follicle in all mares in which both follicles (n = 8) or only the larger follicle (n = 10) was retained. When only the smaller follicle (n = 9) was retained, it became dominant and ovulated in six mares and became atretic in three mares; the difference in diameter between the two follicles on Day 0 was less (p < 0.01) in mares in which the retained ...
Troedsson MH, Liu IK, Crabo BG.After the deposition of semen in the mare's uterus, spermatozoa must be transported to the site of fertilization, be maintained in the female tract until ovulation occurs, and be prepared to fertilize the released ovum. Sperm motility, myometrial contractions, and a spontaneous post-mating uterine inflammation are important factors for the transport and survival of spermatozoa in the mare's reproductive tract. Fertilizable sperm are present in the oviduct within 4 h after insemination. At this time, the uterus is the site of a hostile inflammatory environment. Our data suggest that spermatozoa...
Max MC, Bizarro-Silva C, Búfalo I, González SM, Lindquist AG, Gomes RG, Barreiros TRR, Lisboa LA, Morotti F, Seneda MM.Folliculogenesis is a process of development and maturation of the ovarian follicles, being essential for the maintenance of fertility. In in vivo conditions, 99.9% of the follicles of an ovary do not ovulate and undergo atresia. In order to minimize this loss and to clarify the existing mechanisms, a technique was developed that allows for the in vitro follicular development. The objective of this study was to evaluate the effects of different epidermal growth factor (EGF) concentrations on the in vitro culturing of equine preantral follicles. Ovaries (n = 10) were collected from a local ...
Goudet G, Belin F, Bézard J, Gérard N.The intrafollicular content of LH receptor, alpha-inhibin, and aromatase are known good indicators of follicular status. We investigated the amounts of these proteins in granulosa and cumulus cells in relation to oocyte competence for in vitro maturation, follicular growth, and estrous cycle stage in the mare. Follicular punctures were performed 34 h after an injection of crude equine gonadotropins, either during the follicular phase, at the end of the follicular phase, or during the luteal phase. The cumulus-oocyte complex, granulosa cells, and follicular fluid of follicles larger than 5 mm w...
Sayasith K, Bouchard N, Doré M, Sirois J.The progressive rise in gonadotropins prior to ovulation triggers a marked increase in intrafollicular levels of prostaglandin F(2alpha)(PGF(2alpha)), which is known to interact with PGF(2alpha) receptor (FP). Little is known about the regulation of FP during ovulation. This study was undertaken to characterize the equine FP and its gonadotropin-dependent regulation in preovulatory follicles prior to ovulation. The full-length equine FP encodes a 366-amino acid protein that is 82-93% homologous to other species. Using semi-quantitative RT-PCR/Southern blot, we showed that FP mRNA expression wa...
Spicer LJ, Hammond JM.Development of the ovarian follicle(s) destined for ovulation appears to be a process in which antral follicles undergo a recruitment, selection and subsequent dominance phase. Several intraovarian or autocrine/paracrine regulatory mechanisms have been evoked to explain these processes. One of these potential autocrine/paracrine regulators is a catecholestrogen, 2-hydroxy-estradiol (2-OH-E2). Evidence implicating 2-OH-E2 as an autocrine/paracrine regulator of follicular function is reviewed. Studies have shown 2-OH-E2 to be present in nanomolar concentrations in fluid of human and equine folli...
Van Hoogmoed LM, Galuppo LD.To evaluate use of ENDO-GIA staples and ENDO-Catch pouches for ovariectomy in mares and to evaluate the efficacy of epidural morphine analgesia. Methods: Randomized clinical trial. Methods: Mares (n = 10) with normal ovaries. Methods: An Endo-GIA II stapler (United States Surgical Corp., Norwalk, CT) was used to amputate the ovaries bilaterally, in standing mares, and Endo-Catch II pouches (United States Surgical Corp.) were used for retrieval. Epidural morphine was used in 5 mares, and procedure duration, volume of lidocaine required to desensitize the ovarian pedicle, and sedation were compa...
Aguiar FL, Lunardi FO, Lima LF, Rocha RM, Bruno JB, Magalhães-Padilha DM, Cibin FW, Nunes-Pinheiro DC, Gastal MO, Rodrigues AP, Apgar GA, Gastal EL....This study investigated the effect of adding different concentrations of bovine recombinant follicle-stimulating hormone on the IVC of equine preantral follicles enclosed in ovarian tissue fragments. Randomized ovarian fragments were fixed immediately (fresh noncultured control) or cultured for 1 or 7 days in α-MEM(+) supplemented with 0, 10, 50, and 100 ng/mL FSH and subsequently analyzed by classical histology. Culture media collected on Day 1 or Day 7 and were analyzed for steroids (estradiol and progesterone) and reactive oxygen species (ROS). After Day 1 and Day 7 of culture, 50-ng/mL FS...
Sessions DR, Vick MM, Fitzgerald BP.Matrix metalloproteinases (MMP) and tissue inhibitors of MMP (TIMP) regulate tissue remodeling events necessary for ovulation. Thus, changes in MMP and TIMP expression and protein enzyme activity were examined in vivo and in vitro during follicular development and atresia in the horse. Equine granulosa cells and follicular fluid from medium (15 to 29 mm) healthy and atretic follicles and from large (>30 mm) healthy and preovulatory follicles were collected by transvaginal aspiration. The cells were either snap-frozen (in vivo study) or cultured for 48 h (in vitro study) to determine gene ex...
Rodriguez F, Kramer J, Fales W, Wilson D, Keegan K.This study evaluated bacterial isolates obtained during abdominal surgery and their relationship to short-term incisional complications. Samples of peritoneal fluid and from resection and/or enterotomy sites from 49 horses were cultured, with 96% having at least one positive culture result. The most common isolates were Escherichia coli, Streptococcus spp, and Enterococcus spp. Horses with small intestinal resections were more likely to grow obligate anaerobes and enteric organisms. Horses with small intestinal lesions (+/- resection) were more likely to grow enteric organisms and less likely ...
