Anterior and posterior middle ear congenital cholesteatomas in children.

Congenital cholesteatomas arise from embryonic epithelial cell rests in the middle ear cleft. We report our series of 19 cases observed in 18 children between 1985 and 1990. Clinical data and surgical observations are analyzed. In regard to the location of the lesions, our findings are consistent with most of what has been reported in the literature. Sixty-eight percent of the lesions originated from the anterosuperior part of the mesotympanum. Only 10% were posterosuperiorly located. Pathogenic mechanisms are discussed with respect to the lesion's primary site.

Hearing preservation in acoustic neuroma surgery.

This article reviews the Montreal experience of hearing preservation in acoustic neuroma surgery. The medical records since 1995 of 36 patients who underwent acoustic neuroma extirpation with the intent to preserve hearing were examined. Intraoperative monitoring was conducted using auditory brainstem response measurement with electrocochleography via a transtympanic electrode. The role of intraoperative monitoring in guiding surgical technique and its correlation with postoperative hearing outcome are discussed. A review of the literature regarding hearing preservation in acoustic neuroma surgery is included.

Effects of the Booroola Fec gene on ovarian follicular populations in superovulated Romanov ewes pretreated with a GnRH antagonist.

Endocrine control of follicular growth was studied in mature Romanov ewes carrying (RF+) or not carrying (R+2) the Booroola Fec gene during an oestrous cycle after gonadotrophin-dependent follicles were suppressed by treatment with an antagonist of GnRH (Antarelix, 0.5 mg per day) and superovulatory treatment was administered. The left ovary was removed after 10 days of treatment (saline or Antarelix) and the right ovary was removed at the end of the superovulatory treatment. Ewes of both genotypes treated with Antarelix had lower plasma LH concentrations than did controls from day 0 to day 10. The inhibitory effect of Antarelix on LH concentration increased with day of treatment. The variability in FSH concentrations during the initial 10 days was reduced by Antarelix treatment in both genotypes. Plasma FSH concentrations were higher in RF+ ewes than in R+2 ewes. In both genotypes, FSH concentrations varied significantly with day of treatment, with the lowest concentrations at day 8 and the highest concentrations at day 5. RF+ ewes had a greater total and atretic number of antral follicles 0.62-1.12, 1.12-2.00 and 2.00-3.00 mm in diameter (classes 2, 3 and 4) than did R+2 ewes before and after superovulatory treatment. After superovulatory treatment, the total number of atretic and non-atretic follicles > 3.00 mm in diameter (class 5) increased in both genotypes. Superovulatory treatment also increased the number of total and atretic class 4 follicles in RF+ only. Conversely, superovulatory treatment decreased the mean number of class 3 follicles in both genotypes, while the number of atretic follicles was decreased only in R+2 ewes. Antarelix treatment significantly reduced the percentage of follicles > 2.00 mm in diameter in RF+ but not in R+2 ewes. Antarelix treatment before superovulatory treatment increased the total number of class 4 follicles in both genotypes but the increase was more significant in RF+ than in R+2 ewes. These results indicate that Antarelix pretreatment favours a greater superovulatory response in Romanov ewes carrying the Fec gene because ovulatory follicles are recruited from a wider range of follicular size classes.

Intracranial facial nerve reconstruction.

Surgery for tumours of the cerebellopontine angle (CPA) or the internal auditory canal (IAC) is sometimes complicated by the severing of the seventh nerve. Many procedures are available for facial reanimation. Among these, primary intracranial VII-VII reanastomosis is considered as the method of choice. This series reviews all the cases of primary intracranial facial nerve reconstruction that we have performed either directly or with the use of a nerve graft interposition. Functional results are analyzed according to the House-Brackmann grading scale. The advantages and benefits of this technique are discussed as compared with other methods of facial reanimation, namely, the hypoglossal-facial anastomosis.

The effect of a GnRH agonist on follicular dynamics and response to FSH stimulation in prepubertal calves.

Endocrine control of follicular growth was determined by observing the left ovary of prepubertal calves previously treated with a potent GnRH agonist for 13 days. The ovarian response to hormonal stimulation was determined using the right ovaries of the same animals. Three-month-old crossbred calves were assigned to one of the two following treatment groups: 1) saline control for 13 days, with purified porcine FSH for the last 3 days (n = 5); and 2) GnRHa for 13 days, with purified porcine FSH for the final 3 days (n = 5). The left ovaries were removed from all calves after 10 days, and the right ovaries were removed at the end of treatment. Plasma concentrations of FSH, LH and oestradiol-17 beta were followed up during the GnRHa and pFSH treatments. The maximum macroscopic diameter of the F1 follicle, as determined by daily ultrasonography, did not differ between GnRHa-treated calves (from 6.6 to 10.4 mm) and the saline control calves (from 6.7 to 10.3 mm). Histological analysis of the ovaries showed that the number of follicles > 0.40 mm in diameter varied greatly for calves of the two groups (from 11 to 220 at 10 days). GnRHa significantly increased the mean number of follicles (total and nonatretic) of size class > 5.4 mm as compared to saline control calves (P < 0.05). The FSH treatment significantly increased the mean number of follicles 3.00-5.4 and > 5.4 mm in diameter (P < 0.05), with no change in the number of follicles smaller than 3.00 mm. The rate of atresia of large follicles (3.01-5.40 mm) was significantly reduced by purified porcine FSH treatment in both groups (P < 0.05). In no case did the GnRHa induce ovulation or luteinization of follicles. The LH and FSH concentrations increased transiently after GnRHa treatment on the first day, but afterwards, both hormones increased to only one sixth of what was observed after the initial GnRHa injection treatment. This increase in LH and FSH was observed 1 h after GnRHa treatment on each consecutive day of the experiment and were significantly different in the control group (0 h versus 1 h versus 2 h x saline control versus GnRH agonists groups; P < 0.01). During the superovulatory treatment, FSH concentrations peaked at around 0.70 ng.mL-1 in both saline- and GnRHa-treated groups on the first day but on the last day of surovulatory treatment, FSH concentrations were higher in GnRHa agonist-treated calves than in the control calves (day 11 versus day 12 versus day 13 x saline control versus GnRH agonist treatment groups; P < 0.01). LH profiles were unchanged by surovulatory treatment. Concentrations of oestradiol-17 beta increased significantly over the three days (P < 0.001) of the superovulatory treatments in both groups (P < 0.01). These results indicate that GnRH agonist treatment allows recruited antral follicles to pursue their growth during the early selection process via sustained FSH and LH secretion allowing more than a single large follicle to maintain their growth without going to atresia.

Effects of gonadotropin treatment on ovarian follicle growth, oocyte quality and in vitro fertilization of oocytes in prepubertal gilts.

This study was undertaken to compare the effects of FSH-pituitary (FSH-P), eCG, and a combination of gonadotropins containing 400 IU eCG and 200 IU hCG (PG 600) on the growth of large follicles, oocyte quality and in vitro fertilization (IVF) rate of in vitro matured (IVM) oocytes in prepubertal gilts. The ovaries were removed via midventral laparotomy 48 h (Experiment 1) or 72 h (Experiment 2) after the first injection. In Experiment 1, 30 gilts received 1 of 5 treatments: 1) saline (3 ml i.m., once, n = 6); 2) FSH-P8 (8 mg i.m., twice, with a 24-h interval, n = 6); 3) FSH-P16 (16 mg i.m., twice, with a 24-h interval, n = 6; 4) eCG (1000 IU i.m., once, n = 6); or 5) PG 600 (5 ml i.m., once, n = 6). Compared with saline, treatment with PG 600 or eCG induced significant (P < 0.05) growth of large follicles (> or = 6 mm). In Experiment 2, 16 gilts received 1 of 5 treatments: 1) saline (n = 4); 2) FSH-P8 (n = 4); 3) FSH-P16 (n = 4); 4) eCG (n = 4), or 5) PG 600 (n = 4). The same injection protocol as in Experiment 1 was used. Compared with treatment with FSH-P8 or FSH-P16, eCG increased (P<0.05) the number of large follicles. The proportion of good oocytes was increased (P<0.05) with FSH-P8 or FSH-P16 compared with treatment with eCG or PG 600. Moreover, oocytes from eCG-treated gilts had a greater (P<0.05) rate of male and female pronuclei than FSH-P or saline-treated gilts. In conclusion, treatment with FSH-P resulted in a higher proportion of oocytes with multilayer cumulus cells, whereas treatment with eCG resulted in higher pronuclear rates following in vitro fertilization in prepubertal gilts.

Effect of a single injection of a long-acting gonadotropin-releasing hormone agonist on prepubertal male and female pigs on reproductive organs, growth performance and sensory qualities of pork roasts.

Crossbred pigs (n = 200) were used to study the effects of a long-acting form of gonadotropin-releasing hormone (GnRH) agonist on the reproductive systems of male and female pigs and their growth performance and sensory quality of pork roast. Treatment was a single injection of a controlled release formulation of GnRH agonist [D-Trp6, des-Gly10]-GnRH ethylamide to release 5 micrograms/(kg x day) for 4 months beginning when the pigs were 66 +/- 2 days old. Pigs were allocated to five groups of 40 animals each: males castrated (CM) at 13 +/- 2 days, intact males (IM), treated males (TM), intact females (IF) and treated females (TF). Ovarian and uterine weights at slaughter averaged 3.67 and 79.8 g, respectively, in IF compared with 1.38 and 26.5 g in TF (P < 0.05). Testicular weights were 203 g in IM and 36.8 g in TM (P < 0.05). Microscopic observations of the testes revealed an absence of sperm cells but the presence of germ cells. Steroid concentrations at slaughter from all pigs showed that intact males had significantly more testosterone in their serum (26.36 +/- 9.87 nmol/L) compared with TM, CM, IF or TF groups and that treated males had intermediate concentrations (12.50 +/- 7.44 nmol/L) higher (P < 0.05) than those in CM and TF. Administration of GnRH agonist during the growth period of male pigs had no consistent effect on growth performance, but as compared to IM pigs, some of the carcass characteristics such as meat ratio (49.1 vs 50.2% in TM and IM; P < 0.001), dressing percentage (77.5 vs 76.5% in TM and IM; P < 0.05) and average backfat (20.8 vs 17.6 mm in TM and IM; P < 0.05) were modified by such a treatment. Meat quality, however, as determined by flavor and tenderness evaluations by sensory panelists, were similar (P < 0.05) in all groups and off-flavor scores were lower in TM than in IM (P < 0.001). As for males, backfat and meat ratio were different in TF compared to IF (P < 0.05) and roast juiciness was higher in TF than IF (P < 0.05). These results suggest that GnRH agonist can reduce gonadal secretory activity to castration levels during the growth period of prepubertal male pigs and could be an alternative to surgical castration in the pork industry with no negative effects on growth and meat quality. No advantage to endocrine castration in females was found.

Synchronization of ovarian follicular waves with a gonadotropin-releasing hormone agonist to increase the precision of estrus in cattle: a review.

Treatment with GnRH and PGF2 alpha is a practical method for controlling ovarian follicular and luteal functions and increasing the precision of estrus synchronization in cyclic and acyclic postpartum cows and heifers. This method reduces considerably the period of time needed for estrus detection; it synchronizes the estrous cycle of 70 to 80% of the cyclic cows to within a 4-d interval without any detrimental effect on the fertility rate (65 to 85%). Moreover, resumption of ovarian activity and normal fertility in acyclic cows in favored. Administration of GnRH eliminates the large follicles by ovulation or atresia and induces emergence of a new follicular wave within 3 to 4 d after treatment at any stage of the estrous cycle, but it limits further growth of these emerging follicles by increasing atresia. The precision of estrus and the unaltered fertility rate is due to the synchronized selection of a new larger growing follicle, which becomes the ovulatory follicle after PGF(2 alpha)-induced luteolysis 6 d after GnRH treatment. Also, fixed-time AI programs without the need for estrus detection may be possible using a second injection of GnRH in a GnRH-PGF(2 alpha)-GnRH protocol to ovulate the selected follicle at a precise time. We describe a physiological model to explain how the precision of estrus is improved following PGF(2 alpha)-induced luteolysis, via the effect of pretreatment with GnRH on follicular development and luteal functions in cattle. Application of this model to the development of reliable methods of fixed-time insemination is also explored.

Hormonal induction of ovulation stimulates atresia of antral follicles in gilts.

Two breeds of prepubertal gilts known to differ in their ovarian development were used to compare the effect of hormonally stimulated ovulation on follicle numbers and proportion of follicular atresia in size classes other than preovulatory follicles. Hormonal treatments (hCG or eCG-hCG) were given to Meishan gilts (n = 36) at 3, 2, and 1 standard deviations (SD) before the mean age of puberty (51, 64, and 77 days of age) and to Large White gilts (n = 24) at 3 and 1 SD before the mean age of puberty (140 and 166 days of age). Ovarian follicle populations determined in the right ovaries 18 h after hCG injection alone (hCG) or 72 h after eCG injection (eCG-hCG) were compared with those in the left ovaries, which had been removed prior to injections. Follicles with dispersed cumulus cells around the oocytes (expected ovulations) observed after hormonal treatments (right ovaries) were considered for follicular measures and categorized into specific size classes according to their diameter. Human CG alone did not affect any follicular parameters measured at any age in either of the two breeds studied. The overall population of nonatretic follicles was significantly reduced by the eCFG-hCG treatment in the Large White breed when imposed at either 3 or 1 SD before the mean age of puberty (262.6 vs. 158.8; p < 0.01). Among the various follicle size classes studied, eCG-hCG treatment significantly decreased the mean number of follicles in size classes 2 (1.13-2.00 mm in diameter) and 3 (2.01-3.56 mm in diameter) at either 3 or 1 SD before the mean age of puberty in the Large White gilts (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Estrus synchronization efficiency of PGF2alpha injection in Shorthorn-Hereford and crossbred Charolais cattle not having exhibited estrus at 4 or 7 days prior to treatment.

The objective of this study was to compare the estrus synchronization efficiency of PGF2alpha in cattle (n = 470) not having shown estrus for 4 (D4 treatment) or 7 d (D7 treatment) after onset of the breeding season. The physiological status of crossbred Charolais cows was studied, and their reproductive performance was compared to that of Shorthorn-Hereford cows. The percentage of cows in estrus during the 7 d prior to PGF2alpha treatment was superior (P < 0.01) to that observed during the 4 d preceding PGF2alpha. The daily rates of estrus were similar during the 2 periods. For both the Shorthorn-Hereford (87.8 vs 74.7%; P < 0.03) and crossbred Charolais (87.8 vs 66.3%; P < 0.005) females, the estrus synchronization rate during the 5 d post PGF2alpha was higher in treatment D7 than in the D4 treatment. Therefore, for both Shorthorn-Hereford (92.8 vs 81.4%) and crossbred Charolais (93.1 vs 75.0%) the D7 program permitted insemination in 12 d (before and after PGF2alpha) of a higher percentage (P < 0.01) of females than the D4 program did in 9 d. The intervals PGF2alpha to estrus and their variances were similar for both treatments. The conception rate of Shorthorn-Hereford was the same whether they were inseminated after spontaneous (73.4%) or PGF2alpha-induced estrus (D4 treatment: 78.5%; D7 treatment: 72.2%). However, crossbred Charolais cows inseminated after a PGF2alpha-induced estrus in the D4 treatment had a fertility rate (50.9%) slightly inferior (P < 0.07) to that of cows inseminated after spontaneous estrus (70.1%) or after PGF2alpha-induced estrus in the D7 treatment (67.4%). The reproductive performances of multiparous Shorthorn-Hereford and crossbred Charolais were similar in treatment D7; however, in the D4 treatment, the conception rate of Shorthorn-Hereford was higher than that of crossbred Charolais (81.0 vs 42.9%; P < 0.002). Primiparous crossbred Charolais in the D4 treatment had a slightly lower (P < 0.10) synchronization rate (48%) than nulliparous (71%) and multiparous crossbred Charolais (78%). In contrast, the reproductive performances of nulliparous, primiparous and multiparous crossbred Charolais were similar in the D7 treatment. These results indicate that the efficiency of PGF2alpha to synchronize estrus is greater when the estrus detection period increases from 4 to 7 d before PGF2alpha. Only in the D7 treatment was the fertility rate of crossbred Charolais similar to that of Shorthorn-Hereford.

Development of a schwannoma within a facial nerve neurofibroma: a case report and literature review.

We report the presence of a schwannoma within a neurofibroma of the intratemporal facial nerve. This neurofibroma recurred 39 years after its first excision in the parotid gland. Although some believe that schwannomas and neurofibromas represent the same entity, these tumors present distinctive histopathologic and clinical characteristics, which are discussed. The extreme rarity of a schwannoma developing within a neurofibroma is underlined. This is the first report of such an association occurring within a cranial nerve.

Buserelin alters the development of the corpora lutea in cyclic and early postpartum cows.

Changes in proportions of luteal cells after buserelin treatment were studied in the corpus luteum (CL) that was present at the time of treatment (CLP) and in the buserelin-induced CL (CLI) of cyclic and acyclic postpartum cows. On d 0 of the experimental period, eight cyclic (Cyc-sal) cows were injected with saline, whereas eight cyclic (Cyc-bus) cows and eight acyclic (Acyc-bus) cows were treated i.m. with 8 micrograms of buserelin. On d 3 or 6, ovaries were collected and stained using histological techniques. As determined with the point-counting method, the number of nuclei in the CLP was similar on d 3 in Cyc-bus and Cyc-sal groups but was lower (treatment x day, P < .001) in the Cyc-bus group than in the Cyc-sal group on d 6. The volume of the CLP was similar on d 3 in the two groups but was greater (treatment x day, P < .04) in the Cyc-bus than in the Cyc-sal group on d 6. The number of nuclei in the CLI was greater (P < .001) in cyclic than in acyclic cows on d 3 and 6 after treatment. The volume of the CLI was lower (P < .001) in cyclic than in acyclic cows on d 3 and 6. Buserelin did not change the profile of progesterone in cyclic cows from d 0 to 6, but concentrations of progesterone increased (P < .01) in acyclic cows 3 to 6 d after buserelin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Intratemporal vascular malformations (angiomas): particular clinical features.

Vascular malformations (angiomas) represent 1% of all pathologies of the temporal bone, including those of the cerebellopontine angle (CPA). We report six new cases of angiomas and compare them to the 48 cases listed in the literature published since 1949. Angiomas develop more frequently in the internal auditory canal (IAC) and at the geniculate ganglion (GG). When present in the IAC, rapidly progressive hearing loss is found in 88% of the patients reported in the literature and in 100% of patients in our series; facial nerve dysfunction is found in 72% and 60% of cases, respectively. The average tumour size is less than 10 mm. Acoustic neuroma, the most frequent tumour of this area, causes a slowly progressive sensorineural hearing loss in 75% of cases and facial weakness in 0.8%, according to the literature. Only 10% of acoustic neuromas measure less than 10 mm. Angiomas differ from acoustic neuromas in their rapid onset of sensorineural deafness and much greater incidence of facial nerve dysfunction despite a smaller tumour size.

Influence of corpus luteum and induced ovulation on ovarian follicular dynamics in postpartum cyclic cows treated with buserelin and cloprostenol.

The influence of the corpus luteum (CL) at the time of buserelin treatment and of buserelin-induced ovulation on the dynamics of ovarian follicular development was determined in 18 postpartum cyclic beef cows injected i.m. with 8 micrograms of buserelin on d 0 (d of treatment) and with 500 micrograms of cloprostenol (PGF) 6 d later. From d 0 to onset of estrus, ovaries were examined ultrasonographically, and blood samples were collected daily. Number of medium (5 to 10 mm) follicles and diameters of the two largest (F1 and F2) follicles in each cow were recorded. Cows were grouped according to the presence (CL+) or absence (CL-) of an active CL before buserelin injection and the presence (OV+) or absence (OV-) of a buserelin-induced ovulation (OV). Three groups were formed: CL-OV+ (n = 8), CL+OV+ (n = 6), and CL+OV- (n = 4). Buserelin induced an ovulation in all CL- cows (progesterone [P4] < .3 ng/mL) and in CL+ cows that had P4 < 4 ng/mL but did not in CL+ cows that had P4 > 8 ng/mL. Within CL+ cows, buserelin-induced ovulation (OV+) was associated with a smaller (P < .0001) increase in F1 and F1-F2 diameters and a transient increase in the number of medium follicles that was greater (P < .03) and of a longer duration (P < .01) than in OV- cows. After PGF, the increase in F1 and F1-F2 diameters was still greater in OV+ than in OV- cows (day x OV; P < .05). In all cows, the selection of the preovulatory follicle occurred before PGF injection. Results indicate that a buserelin-induced ovulation was dependent on P4 concentrations at the time of treatment. Subsequently, ovarian follicular dynamics were altered by a GnRH-induced ovulation, but emergence and selection of a large growing follicle occurred in all cows within 6 d of treatment. This follicle became the preovulatory follicle following PGF-induced luteolysis.

Histological populations and atresia of ovarian follicles in postpartum cattle treated with an agonist of gonadotropin-releasing hormone.

Surface and histological changes of ovarian follicles and degree of atresia were characterized 3 and 6 d after a treatment with a GnRH agonist (buserelin) in postpartum beef cows. Sixteen cyclic cows on d 7 of their estrous cycle and eight acyclic cows were used. On d 0 of the experimental period, eight cyclic cows were injected with 2 mL of physiological saline and the remaining eight cyclic cows and the acyclic cows were injected i.m. with 8 micrograms of buserelin. Ovaries were collected 3 or 6 d later (n = 4 cows per group per day). All follicles (> 1.57 mm) were observed microscopically, measured using routine histological techniques, and classified as either nonatretic or atretic, with early or late atresia, and grouped into Class 1, 1.57 to 3.67 mm, Class 2, 3.68 to 8.56 mm, or Class 3, > 8.56 mm. Buserelin induced formation of new corpora lutea in all cows but one (acyclic cow). Class 1 follicles decreased on d 3 but increased on d 6 (day x treatment, P < .004), whereas those of Class 2 increased (P < .07) on both d 3 and 6 after buserelin treatment. However, within Class 2 follicles, we detected an increase on d 3 and 6 in the number (P < .01) and proportion (P < .07) of atretic follicles, an increase in the number of follicles in late atresia on d 6 (day x treatment, P < .03), and a decrease in the number (P < .06) and proportion (P < .03) of nonatretic follicles on d 6 (day x treatment).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative follicular development in Meishan and Large White gilts during prepubertal periods and its relation to hormonal stimulation.

Changes in follicular development in the left ovary and ovarian response to hormonal injections (hCG or eCG and hCG) in the right ovary were studied in Meishan gilts (n = 36) at 3, 2, and 1 standard deviations (SD) before the mean age of puberty (51, 64, and 77 days of age) and in Large White gilts (n = 24) at 3 and 1 SD (140 and 166 days of age). Left ovaries were removed at the time of hormonal treatments and the remaining ovaries were removed 18 h after hCG was injected alone (hCG) or 72 h after eCG was injected (eCG-hCG). Both nonatretic and atretic (> 4 pyknotic bodies) antral follicles > 0.6 mm in diameter were identified in the left ovaries by histological techniques. LH-sensitive follicles were identified in the right ovaries by counting follicles with dispersed cumulus cells around the oocytes. All large White gilts showed the presence of antral follicles at both 3 and 1 SD before puberty while 6, 7, and 12 Meishan gilts had antral follicles > 0.6 mm at 3, 2, and 1 SD before puberty, respectively. In Large White gilts, the mean number of nonatretic antral follicles > 0.6 mm remained constant at 3 and 1 SD before puberty, while in Meishan gilts, the mean number increased as gilts got older. Mean percentage of class 1 nonatretic follicles (0.6-1.12 mm) of the total number of nonatretic follicles increased significantly with age in Meishan gilts (p < 0.02), while those of class 3 (2.01-3.56 mm) decreased significantly (p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Synchronization of estrus and fertility in beef cattle with two injections of buserelin and prostaglandin.

Postpartum beef cows and heifers in Group 1 received 8 mug of buserelin on Day 0 (the beginning of the experiment) and 500 microg of cloprostenol (PGF) on Day 6 (GnRH I, n=54). In Group 2 (GnRH II, n=54), the females were injected with buserelin on Day 0 (8 microg) and Day 3 (4 microg), and PGF on Day 6 and Day 9 for females not detected in estrus previously. Animals were bred by AI 12 hours after the onset of estrus. Blood samples were collected on Day -11 and Day 0 to assess cyclicity and on Day 3 and Days 6 to 12 to examine luteal activity. Progesterone levels did not differ between the 2 groups between Days 0 to 9. In both groups, the proportion of spontaneous estruses from Days 0 to 6 was reduced. Precision of estrus was higher (P<0.005) in the GnRH II group than in the GnRH I group of cows that were detected in estrus between Days 6 and 9. The synchronization rate, interval to estrus, pregnancy and conception rates were similar in GnRH I and GnRH II groups. The conception rate and interval to estrus were similar in cyclic and acyclic cows. Increasing the number of buserelin injections enhanced the precision of estrus, but not the conception rate, without any detrimental effect on luteal activity and induced more estruses in postpartum acyclic beef cattle.

Influence of an agonist of gonadotropin-releasing hormone (buserelin) on estrus synchronization and fertility in beef cows.

The objective of this experiment was to determine the effect of sequential treatment with buserelin (a GnRH agonist) and cloprostenol (a prostaglandin F2 alpha analog) on estrous response and fertility in beef cattle with different ovarian conditions. On d 0 (1st d of treatment), the control group (n = 52, 10 heifers and 42 cows) and the GnRH group (n = 48, 10 heifers and 38 cows) received 2 mL of saline or 2 mL of Receptal (8 micrograms of buserelin), respectively. On d 6, all cows that had not exhibited spontaneous estrus were given i.m. 500 micrograms of cloprostenol (PGF). Ultrasonography on d 0 and assays of progesterone in blood on d -11, 0, and 6 were used to identify follicular and luteal status of animals. Cattle were observed for estrus from d 0 to 10. Cows showing estrus were bred artificially 12 h after onset of estrus. Over the 10-d period, the number of cows detected in estrus and pregnancy and conception rates were identical for the two groups. However, between d 0 and 6, the proportion of cows exhibiting estrus was lower (P less than .01) in the GnRH group than in the control group. Between d 6 and 10, the synchronization rate and precision of estrus were greater (P less than .01) in the buserelin-treated group than in the control group. Conception rate and interval from PGF injection to onset of estrus were not different between the two treatment groups. Presence of a large (greater than 10 mm) follicle on d 0 enhanced synchronization rate and precision of estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of pregnant mare's serum gonadotropin treatment on follicular populations and ovulation rates in prepuberal gilts with two morphologically different ovarian types.

Two experiments were conducted to determine the effects of pregnant mare's serum gonadotropin (PMSG) on follicular populations and ovulation rates in prepuberal gilts with grape-type (GT) and honeycomb-type (HT) ovaries. The follicular populations were determined at 170 d of age (d 0) and 19 d after PMSG (d 19). In Exp. 1, the mean number of macroscopic follicles of Classes 2 and 3 was greater (P less than .05) in GT (n = 11) than in HT (n = 32) ovaries at d 0, whereas the mean number of those of Class 1 was greater (P less than .05) in HT ovaries. At d 19, no difference was observed between the two ovarian types for any class of follicles. The PMSG-induced ovulation rates were comparable between the two ovarian types (8.3 vs 7.9, GT vs HT, respectively; P greater than .10). In Exp. 2, the microscopic follicular populations were determined on right and left ovaries removed, respectively, on d 0 and 19. At d 0, GT ovaries (n = 5) contained a greater number of Class 5 nonatretic (P less than .01) and atretic (P less than .02) follicles than did HT ovaries (n = 5), whereas at d 19 the mean number was not statistically different between the two ovarian types (P greater than .10). In contrast, gilts with HT ovaries contained a greater (P less than .01) number of Class 4 atretic follicles than gilts with GT ovaries at d 0, whereas at d 19 the mean number was not statistically different between the two ovarian types (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Ovarian morphological conditions and the effect of injection of human chorionic gonadotropin on ovulation rates in prepuberal gilts with two morphologically different ovarian types.

The purpose of this experiment was to determine the ovulation rate after treatment with human chorionic gonadotropin (hCG) in two groups of gilts characterized by different ovarian morphology: grape-type (GT; n = 11) and honeycomb-type (HT; n = 7). At 170 d of age (d 0), gilts were examined by laparoscopy and ovarian type was determined by the distribution of macroscopic follicles present on the ovarian surface. Five to ten minutes after surgery, each gilt received a single injection (i.m.) of 750 IU of hCG. At d 0, GT ovaries had a greater number of large follicles (greater than or equal to 6 mm) than HT ovaries (10.0 +/- .5 vs 2.6 +/- .3; P less than .05), whereas HT ovaries had more small follicles (1 to 3 mm; HT: 42.3 +/- .8 vs GT: 26.7 +/- .9; P less than .05) and total follicles (HT: 59.4 +/- 2.3 vs GT: 52.2 +/- 1.5; P less than .05), although numbers of medium follicles (4 to 5 mm) were similar (GT: 15.6 +/- .8 vs HT: 14.6 +/- 1.7; P greater than .10). Number of induced corpora lutea (CL) per ovary was greater (P less than .05) in gilts with GT ovaries (10.59 +/- 2.9 CL) than in gilts with HT ovaries (5.21 +/- .66 CL). Total weight of luteal tissue (LT) per ovary and serum progesterone concentrations 8 d after induction of ovulation were greater in GT gilts than in HT gilts (GT: 6.37 +/- 1.09 g vs HT: 3.31 +/- .49 g for LT, P less than .05; GT: 21.08 +/- 4.76 ng/ml vs HT: 13.40 +/- 2.05 ng/ml for progesterone, P less than .07).(ABSTRACT TRUNCATED AT 250 WORDS)