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K Kot

Publications and source records attributed to K Kot.

51 records · Page 3Linked to original sources
PubMed1996

Relationships between FSH and ovarian follicular waves during the last six months of pregnancy in cattle.

Follicles were monitored daily by ultrasound and blood samples for FSH assay were collected daily from eight heifers from day 90 of pregnancy to the emergence of the first postpartum follicular wave. Follicles > or = 6 mm in diameter emerged in groups or waves in each heifer (P < 0.005). Follicular waves developed rhythmically throughout pregnancy, except that follicles > or = 6 mm were not detected during the last 21.6 +/- 2.4 (mean +/- SEM) days of pregnancy. The characteristics of the first follicular wave after day 90 were similar to previous reports for days 10-100. However, between months 4 (days 90-119) and 5, there was a decrease (P < 0.05) in monthly means for maximum diameter (mm) of largest (21.1 +/- 0.5 versus 9.5 +/- 0.5) and second largest (8.0 +/- 0.3 versus 6.9 +/- 0.2) follicles, duration of the interwave interval (8.1 +/- 0.4 versus 6.6 +/- 0.3 days), and number of follicles per wave (3.7 +/- 0.4 versus 2.5 +/- 0.4). Averaged over all follicular waves during months 4-9, the concentrations of FSH normalized to the emergence of a follicular wave increased (P < 0.05) over the 3 days before emergence, reached peak values on the day of emergence of the future dominant follicle at 4 mm, and decreased (P < 0.05) over the 3 days following emergence. Surges in FSH concentrations occurred throughout pregnancy, but during the last 30 days of pregnancy the number of surges was reduced and each heifer had one or two ineffective surges (no follicular wave detected). The temporal relationship between FSH surges and emergence of waves was closer (P < 0.01) than would be expected if the two events were independent. Surges of FSH occurred rhythmically even when there was no follicular response (no follicle > 5 mm). In association with waves in which the largest follicle reached > or = 10 mm compared with 6-9 mm, there was greater depression in the FSH nadir, longer intervals from FSH peak to nadir, and longer intervals between adjacent FSH peaks and adjacent waves.

Animals↗
PubMed1995

Associations between emergence of follicular waves and fluctuations in FSH concentrations during the estrous cycle in ewes.

Folliculogenesis was studied daily in 16 interovulatory intervals in 5 Polypay ewes from mid February through April using transrectal ultrasonic imaging. The 3-mm follicles attaining > or = 5 mm on Days--1 (ovulation=Day 0) to 11 showed significant peak numbers on Days 0, 5 and 10. The number of 3- and 4-mm follicles that did not reach > 4 mm was not significant, indicating that these follicles did not manifest a wave pattern. A follicular wave was defined as one or more follicles growing to > or = 5 mm; the day the follicles were 3 mm was the day of wave emergence, and the first wave after ovulation was Wave 1. Waves 1, 2 and 3 emerged on Days -1 to 2,4 to 7 and 8 to 10, respectively. Four interovulatory intervals in April were short (9 to 14 d), indicating the end of the ovulatory season. In the remaining 12 intervals, the ovulatory wave was Wave 3 in one interval, Wave 4 in 8 intervals, and Wave 5 or 6 in 3 intervals. The ovulatory wave followed the rhythmic pattern of Waves 1 to 3 by emerging on Days 11 to 14 in 50% of the intervals. In the remaining intervals, either the ovulatory wave was Wave 4 but did not emerge until Day 16 or other waves intervened between Wave 3 and the ovulatory wave. The longest intervals (22, 24 and 24 d) had >4 waves. Based on a cycle-detection program, peak values of FSH fluctuations were temporally associated with the emergence of waves as indicated by the following: 1) tendency (P < 0.08) for an increase in FSH concentrations between 3 and 2 days before emergence of a wave; 2) close agreement between mean number of waves per interval (mean +/- SEM, 4.1 +/- 0.3) and mean number of identified FSH fluctuations (4.5 +/- 0.3); 3) close agreement in length of interwave intervals (4.0 +/- 0.3) and interpeak (FSH) intervals (3.6 +/- 0.2); 4) positive correlation (r(2)=0.8) for number of the 2 events (follicular waves and FSH fluctuations) within intervals; and 5) a closer (P < 0.01) temporal relationship between the 2 events than would have been expected if the events were independent. The results support a relationship between transient increases in FSH concentrations and emergence of follicular waves throughout the interovulatory interval in Polypay ewes, with the 2 events occurring approximately every 4 d.

Journal Article↗
PubMed1995

Physical characteristics of the uterus during the bovine estrous cycle and early pregnancy.

Uterine tone, uterine contractility and endometrial echotexture were monitored daily in heifers during the estrous cycle (n = 6; Days 0 to 21; ovulation = Day 0) and during early pregnancy (n = 7; Days 0 to 26). Uterine tone was assessed by transrectal palpation and scored from 1 (flaccid) to 5 (turgid) by an operator who had no knowledge of reproductive status, day, or group. The main effect of day was significant, but the group effect and the group-by-day interaction were not. Uterine tone scores were high during the periovulatory period (Days--1, 0, 1), decreased (P < 0.05) to low levels on Days 3 and 4, and then increased (P < 0.05) from Days 4 to 10. The increase in tone during early diestrus was confirmed (P < 0.05) in a second experiment. Uterine contractility was assessed by transrectal ultrasonography during a five-minute scan of the caudal portions of the uterine horns and scored from 1 (minimal contractility) to 4 (maximal contractility). The main effects of day and the group-by-day interaction were significant. Contractility scores in both groups were highest just before or on the day of ovulation (Days--1,0) and then decreased (P < 0.05) until Day 11. After Day 16, the scores increased (P < 0.05) in the nonbred heifers and remained low in the pregnant heifers. Endometrial echotexture scores were different among days (P < 0.0001), between the 2 groups (P < 0.02), and for the group-by-day interaction (P < 0.0001). Echotexture scores in both groups peaked just before ovulation (Day--1) and then decreased (P < 0.05) until Day 4. After Day 16, the scores increased in the nonbred group but remained low in pregnant heifers. In summary, uterine contractility and endometrial scores had similar profiles, being high during the periovulatory period and low thereafter; the levels rose in association with the end of the interovulatory interval in nonbred heifers, but remained at low levels in pregnant heifers. Uterine tone scores were also high during the periovulatory period and decreased to low levels several days postovulation, but then, in contrast with the other end points, began to increase in both the nonbred and pregnant heifers.

Journal Article↗
PubMed1995

Ultrasound-guided intrafollicular treatment in mares.

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 a linear-array trans vaginal transducer. The outer needle was pushed through the vaginal wall and the inner needle was then advanced into the follicle during monitoring on the ultrasound screen. The turbulence in the follicular fluid associated with injection was observable on the screen. Seven follicles were successfully injected in each group. The follicular fluid in the control follicles remained anechoic until the follicle was no longer identifiable or ovulated. All 7 follicles in the eCG group showed ultrasonic indications of luteinization, based on the formation of an echogenic, thickened wall or area. Five of the 7 developed a central area that had the ultrasonic appearance of a blood clot similar to the appearance of a corpus hemorrhagicum. Ovulation was not detected in any of the eCG-treated follicles. The maximum post-treatment diameter of follicles was greater (P < 0.05) for the eCG group (32.7 +/- 3.8 mm) than for the control group (23.4 +/- 1.8 mm). The mean diameter for the first 5 days post-treatment (before the occurrence of an ovulation in any mare) was also greater (P < 0.002) in the eCG group (21.6 +/- 0.8 mm vs 19.6 +/- 0.8 mm). Results indicated that this novel research approach is practical and has potential for studies on folliculogenesis. The technique provides a research model between the extremes of an in vitro culture system and treatment of the whole animal.

Journal Article↗
PubMed1994

Follicular dynamics during the ovulatory season in goats.

Growth and regression of ovarian follicles>or=3 mm were studied by transrectal ultrasonography for 4 interovulatory intervals in each of 5 Saanen goats. The observed number of growing identified 4-mm follicles per day differed (P<0.05) from randomness, indicating that follicles, on the average, emerged in groups (waves). Averaged over all interovulatory intervals, the number of 3-mm follicles on each day that later reached >or=6 mm followed a pattern of significant peaks on Days 0 (ovulation), 4,8 and 14. A follicular wave was defined by consecutive days of entry of follicles>or=6 mm into the wave, and the day of emergence was defined as the first day that the >or=6 mm follicles were 3 mm. In 15 of 20 (75%) interovulatory intervals, 1 wave emerged during each of Day -2 to Day 1 (Wave 1); Days 2 to 5 (Wave 2); Days 6 to 9 (Wave 3); and Days 10 to 15 (Wave 4). Ovulation occurred during Wave 4. The mean days of emergence of Waves 1 to 4 were Days -1, 4, 8 and 13, respectively. However, in 5 of these 15 interovulatory intervals, 50% of the apparent waves merged or were continuous so that a distinction could not be made between 2 waves. The largest follicle grew to a larger (P<0.05) maximum diameter for Waves 1 (8.7+/-0.3 mm) and 4 (9.7+/-0.3 mm) than for Waves 2 (7.2+/-0.2 mm) and 3 (7.3+/-0.2 mm). The following observations suggested that the phenomenon of follicular dominance was more common during Waves 1 and 4 than during Waves 2 and 3: 1) the interwave intervals (days) were longer (P<0.05) for Waves 1 (3.4+/-0.2) and 4 (4.3+/-0.6) than for Waves 2 and 3 (2.5+/-0.2 for each wave) and 2) the correlation between maximum diameter of largest follicle and the subsequent interwave interval was significant for Waves 1 and 4 but not for Waves 2 and 3. The 5 remaining interovulatory intervals were irregular and involved more than 4 waves, including 2 interovulatory intervals with prolonged follicular phases (14 and 21) and failures of ovulation. In conclusion, the predominant follicular-wave pattern was 4 waves with ovulation from Wave 4, and apparent follicular dominance was expressed during some follicular waves, especially during Waves 1 and 4.

Journal Article↗
PubMed1991

Embryo recovery from mares exposed to a year-to-year artificially prolonged daylength.

The aim of the experiment was to determine the effect of a year-to-year prolonged daylength on the patterns of equine reproductive activity and results of embryo recovery. Experiments using Konik Polski mares were conducted over four reproduction seasons. Five mares were exposed to a regimen of artificially prolonged daylength (APD) and another five mares in a control group were kept under conditions of natural daylight. Both the control and experimental groups were examined for appearance of estrus, ovulation and also for the state of their coats. A single stallion was used for breeding all of the mares. The embryos were recovered nonsurgically 6 to 9 days after ovulation. All of the mares exposed to APD showed increased ovarian activity, which commenced earlier than in the control group. About 19% more ovulations were detected in the experimental group. The average number of ovulations per lighted mare per year was 15.3, while in the control group it was 12.4 ovulations (P<0.05). However, the embryo recovery rate and total number of embryos obtained from the mares exposed to APD did not exceed the number of embryos collected from the control mares (P<0.05). Modification of daylength had a visible effect on the mares by producing a change in their coats.

Journal Article↗