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The Effect of Ligation or Separation between the Intrauterine Device Horn and Adjacent Ovary on Implantation in the Hamster*
Vol. 29, No.3, March 1978 Printed in U.s.A.
FERTILITY AND STERILITY Copyright" 1978 The American Fertility Society
THE EFFECT OF LIGATION OR SEPARATION BETWEEN THE INTRAUTERINE DEVICE HORN AND ADJACENT OVARY ON IMPLANTATION IN THE HAMSTER*
WALTER J. BO, PH.D.t WAYNE A. KRUEGER, PH.D. C. MURRAY BARTLEY, M.S. Department of Anatomy, Bowman Gray School of Medicine, Wake Forst University, Winston-Salem, North Carolina 27103
The purpose of this study was to determine whether the luteolytic action of an intrauterine device (IUD) is suppressed following interruption of the continuity between the IUD uterine horn and the adjacent ovary. After several estrous cycles, a silk IUD was placed in the cervical end of one uterine horn of adult hamsters. The animals were then mated, and on day 6 of gestation the ovary and oviduct contralateral to the IUD were removed and a ligature was placed between the IUD horn and the adjacent ovary. The hamsters were killed on day 9 or day 13 of gestation. Fetal development in the contralateral horn was suppressed on day 13 but not on day 9. In the second study the animals were treated as in the first study except that the communication between the IUD horn and the adjacent ovary was severed completely. The hamsters were killed on day 9 or day 13. On both days 9 and 13 normal fetal development was observed in the control horn; no implantation sites were present in the IUD side. In the control (non-IUD) animals of each study, normal fetuses were present in both uterine horns. The study demonstrates that luteolysis does not occur if there is complete disruption of the communication between the IUD horn and ovary. The study also demonstrates that, since implantation did not occur in the IUD horn with a normally functioning ipsilateral ovary, the luteolytic action of the device is not the prime factor in suppressing implantation in the hamster.
activity of the corpus luteum. However, before this concept can be accepted, it is necessary to determine whether disruption of the continuity between the IUD horn and the adjacent ovary allows normal activity of the ovary. Therefore, a series of experiments were undertaken to determine whether ligation or complete severance between the IUD horn and the ipsilateral ovary prevents suppression of the corpus luteum. By using these experimental models it will be possible to determine whether the luteolytic factor is of prime importance in suppressing implantation in the IUD horn or whether other factors may be involved.
A recent hypothesis concerning the biologic action of an intrauterine device (IUD) in the hamster involves the release of prostaglandin F 2" (PGF 2,,) from the horn bearing the device which causes a suppression of progesterone secretion. 1,2 Bo et al. 3 demonstrated that in the hamster the ovary ipsilateral to the IUD is nonfunctional; pregnancy was not maintained in the opposite horn in animals in which the ovary contralateral to the device was removed on day 6 of gestation. However, in control animals without the IUD, one ovary maintained pregnancy in both horns. All of these studies indicate that in the hamster the luteolytic factor from the IUD horn passes to the ovary and suppresses the normal physiologic
MATERIALS AND METHODS
Received July 14, 1977; revised October 11, 1977; accepted October 18, 1977. *Supported by Grant HD 06210-06 from the United States Public Health Service. tTo whom reprint requests should be addressed.
Golden hamsters (Mesocricetus auratusJ 60 to 75 days of age were used throughout the study. All animals were allowed free access to Purina
351
352
BO ET AL.
laboratory chow and water; they were maintained on a photoperiod of 14 hours of light/24 hours. To establish the regularity of the estrous cycle, the animals were followed through three cycles prior to experimentation. At the fourth observed estrus, a silk (3-0) IUD (10 to 12 mm long) was inserted into the cervical end of one uterine horn by piercing the antimesometrial wall; the control hamsters did not receive an IUD. The first study was designed to determine whether ligation between the ovary and the IUD horn prevents suppression of the corpus luteum. Following the insertion of the IUD the animals were mated at the next estrus. On day 6 of gestation the ovary and oviduct contralateral to the device were removed and a ligature was placed between the IUD horn and the adjacent oviduct. The animals were killed on day 9 or day 13 of gestation, and the uterine horns were examined for normal implantation and resorption sites. The purpose of the second study was to determine the effect of complete severance of the continuity between the IUD horn and the adjacent ovary. The hamsters were mated at the next estrus following the insertion of the device. On the morning of day 6 of pregnancy, the ovary and oviduct contralateral to the IUD horn were removed and the connection between the IUDbearing uterine horn and adjacent oviduct was severed. The tubal end of the IUD horn was anchored to the dorsal body wall. Animals were killed on day 9 or day 13 of gestation, and the implantation and resorption sites were counted. The control animals for each study were treated in a manner similar to that of the experimental animals except that IUDs were not inserted; the hamsters were autopsied on day 14 of gestation.
RESULTS
The data on the effect of ligation between the ovary and IUD horn on the functional activity of the ovary are shown in Table 1. Fetal development was suppressed in the contralateral control horns in animals that were killed on day 13 but not in the hamsters killed on day 9. Resorption sites were present in the contralateral uterine horns of all of the hamsters killed on day 13. Implantation did not occur in the IUD horns. The results on the effect of complete severance of the ovary from the IUD horn are shown in Table 2. The ovary on the side of the device remained functional; normal fetal development occurred in the horn opposite the IUD horn.
March 1978 TABLE 1. Effect of Uterine Ligation" on Implantation in the Hamster" Uterine horn
No. of animals
Day killed
% With
fetuses
Average no. of fetuses :!::: SEM
5.1 ± 0.6 0
Control IUD"
8
9
100 0
Control IUD"
8
13
0 0
Control Non-IUD"
5
14
100 100
j
0 0 4.8 ± 0.6 4.0 ± 0.4 {
"Ligatures were placed between the horn and the adjacent ovary on day 6 of pregnancy. "The ovary contralateral to the ligated horn was removed on day 6 of gestation.
In the control (non-IUD) hamsters, normal fetuses were present in both uterine horns on day 14 of gestation (Tables 1 and 2). DISCUSSION
This report shows that, when the communication between the ovary and the IUD horn is completely disrupted, luteolysis does not occur and pregnancy is maintained in the contralateral, nonIUD horn of hemiovariectomized animals. This finding demonstrates that the luteolytic factor arises in the IUD horn and passes to the ovary. On the other hand, if the disruption between the two organs is achieved by ligature, normal luteal function continues until day 9 of pregnancy, but at a later time interval (day 13), it is lost; resorption sites were present in the contralateral, non-IUD horn. This phenomenon indicates that a revascularization of the area between the IUD horn and the ovary may have occurred during the increased time interval, allowing the uterine luteolytic factor to reach the ovary from the uterus. Our previous studies have demonstrated that the ovary adjacent to the device is nonfunctional; pregnancy is not maintained in the contralateral, non-IUD horn. 3 Data from our TABLE 2. Effect of Complete Separation" of a Uterine Horn from the Adjacent Ovary on Implantation in the Hamster" Uterine horn
No. of animals
Day killed
% With
fetuses
Average no. of fetuses ± SEM
Control IUD"
8
9
100 0
5.6 ± 0.5 0
Control IUD"
8
13
100 0
5.5 ± 0.7 0
Control Non-IUD"
5
14
100 100
4.8 ± 0.7 5.2 ± 0.5
"The communication between the uterine horn and the adjacent ovary was severed on day 6 of gestation. "The ovary contralateral to the severed horn was removed on day 6 of gestation.
I
I
i ~-
Vol. 29, No.3
DISRUPTION OF IUD HORN FROM OVARY ON IMPLANTATION
laboratory show that the regression of the corpus luteum adjacent to the IUD horn is due to the device and not to the absence of implantation sites. 4 How the luteolytic factor reaches the ovary from the uterus has been postulated to occur through the utero-ovarian vein and ovarian artery. In sheep, a countercurrent mechanism between the vein and artery for the passage of the luteolytic factor from the uterus to the ovary has been demonstrated. 5 Whether such a mechanism is present in the hamster has not been clearly defined. However, on the basis of the morphology of the vascular pattern between the uterus and the ovary, Del Campo and Ginther 6 believed that an exchange mechanism between the ovarian vein and artery was possible in the hamster. There is evidence that the luteolytic factor in the hamster is prostaglandin. An increase in the concentration of prostaglandin in IUD horns has been correlated with a decrease in ovarian progesterone secretion, 1,2 and exogenously administered PGF 2" terminates pregnancy in the hamster.7 Electronmicroscopic studies in our laboratory have demonstrated that luteal regression in the hamster is more pronounced on day 8 than on day 5 of gestation following injections of PGF 2".8 In animals with bilateral IUDs, regression of the corpus luteum was less severe on day 5 of pregnancy than in PGF 2a-treated hamsters, but on day 8 regression of luteal cells was similar in the two groups. Although the evidence indicates that in the hamster prostaglandin is the luteolytic factor which arises from the IUD horn, more direct studies are needed to establish this phenomenon. This study also demonstrates that the luteolytic action of the IUD may not be the prime factor in the biologic action of the device in the hamster. Implantation of the blastocyst did not occur in the IUD horn even with the presence of an adjacent functional ovary. Therefore, this in-
353
dicates that, in addition to the luteolytic action of the IUD, another factor of major importance seems to be implicated in the anti-implantational effect of the IUD. Our previous studies have demonstrated in the rat that the influx of neutrophils associated with the presence of an IUD is an important factor in suppressing implantation of the blastocyst. 9-11 Whether this factor has a significant role in the hamster must be ascertained. REFERENCES 1. Saksena SK, Lau IF, Castracane VD: Prostaglandin mediated action of IUDs. II. F prostaglandins (PGF) in the uterine horn of pregnant rats and hamsters with intrauterine devices. Prostaglandins 5:97, 1974 2. Saksena SK, Shaikh AA: Effect of intrauterine devices on preovulatory LH and progesterone levels in the cyclic hamster. J Reprod Fertil 38:205, 1974 3. Bo WJ, Krueger WA, Bartley CM: Influence of the IUD on ovarian activity in the hamster and rat. J Reprod Fertil 48:229, 1976 4. Bo WJ, Krueger WA, Bartley CM: Unpublished data 5. Barrett S, DeB Blockey MA, Brown JM, Cumming lA, Goding JR, Mole BJ, Obst JM: Initiation of the oestrous cycle in the ewe by infusions of PGF 2 a into the autotransplanted ovary. J Reprod Fertil 24:136, 1971 6. Del Campo CH, Ginther OJ: Vascular anatomy of the uterus and ovaries and the unilateral luteolytic effect of the uterus: guinea pigs, rats, hamsters and rabbits. Am J Vet Res 33:2561, 1972 7. Labhsetwar AP: Effects of prostaglandin F 2" on some reproductive processes of hamsters and rats. J Endocrinol 53:201, 1972 8. Hubbard CJ, Bo WJ: The effect of the IUD and prostaglandin F 2 a on luteolysis in the pregnant hamster. Anat Rec 187:609, 1977 9. Krueger WA, Bo WJ, Garrison BM: Early uterine neutrophilic response to silk and polyethylene IUDs in the rat. Contraception 8:549, 1973 10. Bo WJ, Krueger WA, Bartley CM: The influence of chlorambucil on IUD-induced uterine neutrophils. Contraception 10:667, 1974 11. Bo WJ, Krueger WA, Sain LE: Effect of direct injection of neutrophils from uterine horns of rats containing intrauterine devices into recipient pregnant uteri. Fertil Steril 27:1318, 1976
FERTILITY AND STERILITY Copyright" 1978 The American Fertility Society
THE EFFECT OF LIGATION OR SEPARATION BETWEEN THE INTRAUTERINE DEVICE HORN AND ADJACENT OVARY ON IMPLANTATION IN THE HAMSTER*
WALTER J. BO, PH.D.t WAYNE A. KRUEGER, PH.D. C. MURRAY BARTLEY, M.S. Department of Anatomy, Bowman Gray School of Medicine, Wake Forst University, Winston-Salem, North Carolina 27103
The purpose of this study was to determine whether the luteolytic action of an intrauterine device (IUD) is suppressed following interruption of the continuity between the IUD uterine horn and the adjacent ovary. After several estrous cycles, a silk IUD was placed in the cervical end of one uterine horn of adult hamsters. The animals were then mated, and on day 6 of gestation the ovary and oviduct contralateral to the IUD were removed and a ligature was placed between the IUD horn and the adjacent ovary. The hamsters were killed on day 9 or day 13 of gestation. Fetal development in the contralateral horn was suppressed on day 13 but not on day 9. In the second study the animals were treated as in the first study except that the communication between the IUD horn and the adjacent ovary was severed completely. The hamsters were killed on day 9 or day 13. On both days 9 and 13 normal fetal development was observed in the control horn; no implantation sites were present in the IUD side. In the control (non-IUD) animals of each study, normal fetuses were present in both uterine horns. The study demonstrates that luteolysis does not occur if there is complete disruption of the communication between the IUD horn and ovary. The study also demonstrates that, since implantation did not occur in the IUD horn with a normally functioning ipsilateral ovary, the luteolytic action of the device is not the prime factor in suppressing implantation in the hamster.
activity of the corpus luteum. However, before this concept can be accepted, it is necessary to determine whether disruption of the continuity between the IUD horn and the adjacent ovary allows normal activity of the ovary. Therefore, a series of experiments were undertaken to determine whether ligation or complete severance between the IUD horn and the ipsilateral ovary prevents suppression of the corpus luteum. By using these experimental models it will be possible to determine whether the luteolytic factor is of prime importance in suppressing implantation in the IUD horn or whether other factors may be involved.
A recent hypothesis concerning the biologic action of an intrauterine device (IUD) in the hamster involves the release of prostaglandin F 2" (PGF 2,,) from the horn bearing the device which causes a suppression of progesterone secretion. 1,2 Bo et al. 3 demonstrated that in the hamster the ovary ipsilateral to the IUD is nonfunctional; pregnancy was not maintained in the opposite horn in animals in which the ovary contralateral to the device was removed on day 6 of gestation. However, in control animals without the IUD, one ovary maintained pregnancy in both horns. All of these studies indicate that in the hamster the luteolytic factor from the IUD horn passes to the ovary and suppresses the normal physiologic
MATERIALS AND METHODS
Received July 14, 1977; revised October 11, 1977; accepted October 18, 1977. *Supported by Grant HD 06210-06 from the United States Public Health Service. tTo whom reprint requests should be addressed.
Golden hamsters (Mesocricetus auratusJ 60 to 75 days of age were used throughout the study. All animals were allowed free access to Purina
351
352
BO ET AL.
laboratory chow and water; they were maintained on a photoperiod of 14 hours of light/24 hours. To establish the regularity of the estrous cycle, the animals were followed through three cycles prior to experimentation. At the fourth observed estrus, a silk (3-0) IUD (10 to 12 mm long) was inserted into the cervical end of one uterine horn by piercing the antimesometrial wall; the control hamsters did not receive an IUD. The first study was designed to determine whether ligation between the ovary and the IUD horn prevents suppression of the corpus luteum. Following the insertion of the IUD the animals were mated at the next estrus. On day 6 of gestation the ovary and oviduct contralateral to the device were removed and a ligature was placed between the IUD horn and the adjacent oviduct. The animals were killed on day 9 or day 13 of gestation, and the uterine horns were examined for normal implantation and resorption sites. The purpose of the second study was to determine the effect of complete severance of the continuity between the IUD horn and the adjacent ovary. The hamsters were mated at the next estrus following the insertion of the device. On the morning of day 6 of pregnancy, the ovary and oviduct contralateral to the IUD horn were removed and the connection between the IUDbearing uterine horn and adjacent oviduct was severed. The tubal end of the IUD horn was anchored to the dorsal body wall. Animals were killed on day 9 or day 13 of gestation, and the implantation and resorption sites were counted. The control animals for each study were treated in a manner similar to that of the experimental animals except that IUDs were not inserted; the hamsters were autopsied on day 14 of gestation.
RESULTS
The data on the effect of ligation between the ovary and IUD horn on the functional activity of the ovary are shown in Table 1. Fetal development was suppressed in the contralateral control horns in animals that were killed on day 13 but not in the hamsters killed on day 9. Resorption sites were present in the contralateral uterine horns of all of the hamsters killed on day 13. Implantation did not occur in the IUD horns. The results on the effect of complete severance of the ovary from the IUD horn are shown in Table 2. The ovary on the side of the device remained functional; normal fetal development occurred in the horn opposite the IUD horn.
March 1978 TABLE 1. Effect of Uterine Ligation" on Implantation in the Hamster" Uterine horn
No. of animals
Day killed
% With
fetuses
Average no. of fetuses :!::: SEM
5.1 ± 0.6 0
Control IUD"
8
9
100 0
Control IUD"
8
13
0 0
Control Non-IUD"
5
14
100 100
j
0 0 4.8 ± 0.6 4.0 ± 0.4 {
"Ligatures were placed between the horn and the adjacent ovary on day 6 of pregnancy. "The ovary contralateral to the ligated horn was removed on day 6 of gestation.
In the control (non-IUD) hamsters, normal fetuses were present in both uterine horns on day 14 of gestation (Tables 1 and 2). DISCUSSION
This report shows that, when the communication between the ovary and the IUD horn is completely disrupted, luteolysis does not occur and pregnancy is maintained in the contralateral, nonIUD horn of hemiovariectomized animals. This finding demonstrates that the luteolytic factor arises in the IUD horn and passes to the ovary. On the other hand, if the disruption between the two organs is achieved by ligature, normal luteal function continues until day 9 of pregnancy, but at a later time interval (day 13), it is lost; resorption sites were present in the contralateral, non-IUD horn. This phenomenon indicates that a revascularization of the area between the IUD horn and the ovary may have occurred during the increased time interval, allowing the uterine luteolytic factor to reach the ovary from the uterus. Our previous studies have demonstrated that the ovary adjacent to the device is nonfunctional; pregnancy is not maintained in the contralateral, non-IUD horn. 3 Data from our TABLE 2. Effect of Complete Separation" of a Uterine Horn from the Adjacent Ovary on Implantation in the Hamster" Uterine horn
No. of animals
Day killed
% With
fetuses
Average no. of fetuses ± SEM
Control IUD"
8
9
100 0
5.6 ± 0.5 0
Control IUD"
8
13
100 0
5.5 ± 0.7 0
Control Non-IUD"
5
14
100 100
4.8 ± 0.7 5.2 ± 0.5
"The communication between the uterine horn and the adjacent ovary was severed on day 6 of gestation. "The ovary contralateral to the severed horn was removed on day 6 of gestation.
I
I
i ~-
Vol. 29, No.3
DISRUPTION OF IUD HORN FROM OVARY ON IMPLANTATION
laboratory show that the regression of the corpus luteum adjacent to the IUD horn is due to the device and not to the absence of implantation sites. 4 How the luteolytic factor reaches the ovary from the uterus has been postulated to occur through the utero-ovarian vein and ovarian artery. In sheep, a countercurrent mechanism between the vein and artery for the passage of the luteolytic factor from the uterus to the ovary has been demonstrated. 5 Whether such a mechanism is present in the hamster has not been clearly defined. However, on the basis of the morphology of the vascular pattern between the uterus and the ovary, Del Campo and Ginther 6 believed that an exchange mechanism between the ovarian vein and artery was possible in the hamster. There is evidence that the luteolytic factor in the hamster is prostaglandin. An increase in the concentration of prostaglandin in IUD horns has been correlated with a decrease in ovarian progesterone secretion, 1,2 and exogenously administered PGF 2" terminates pregnancy in the hamster.7 Electronmicroscopic studies in our laboratory have demonstrated that luteal regression in the hamster is more pronounced on day 8 than on day 5 of gestation following injections of PGF 2".8 In animals with bilateral IUDs, regression of the corpus luteum was less severe on day 5 of pregnancy than in PGF 2a-treated hamsters, but on day 8 regression of luteal cells was similar in the two groups. Although the evidence indicates that in the hamster prostaglandin is the luteolytic factor which arises from the IUD horn, more direct studies are needed to establish this phenomenon. This study also demonstrates that the luteolytic action of the IUD may not be the prime factor in the biologic action of the device in the hamster. Implantation of the blastocyst did not occur in the IUD horn even with the presence of an adjacent functional ovary. Therefore, this in-
353
dicates that, in addition to the luteolytic action of the IUD, another factor of major importance seems to be implicated in the anti-implantational effect of the IUD. Our previous studies have demonstrated in the rat that the influx of neutrophils associated with the presence of an IUD is an important factor in suppressing implantation of the blastocyst. 9-11 Whether this factor has a significant role in the hamster must be ascertained. REFERENCES 1. Saksena SK, Lau IF, Castracane VD: Prostaglandin mediated action of IUDs. II. F prostaglandins (PGF) in the uterine horn of pregnant rats and hamsters with intrauterine devices. Prostaglandins 5:97, 1974 2. Saksena SK, Shaikh AA: Effect of intrauterine devices on preovulatory LH and progesterone levels in the cyclic hamster. J Reprod Fertil 38:205, 1974 3. Bo WJ, Krueger WA, Bartley CM: Influence of the IUD on ovarian activity in the hamster and rat. J Reprod Fertil 48:229, 1976 4. Bo WJ, Krueger WA, Bartley CM: Unpublished data 5. Barrett S, DeB Blockey MA, Brown JM, Cumming lA, Goding JR, Mole BJ, Obst JM: Initiation of the oestrous cycle in the ewe by infusions of PGF 2 a into the autotransplanted ovary. J Reprod Fertil 24:136, 1971 6. Del Campo CH, Ginther OJ: Vascular anatomy of the uterus and ovaries and the unilateral luteolytic effect of the uterus: guinea pigs, rats, hamsters and rabbits. Am J Vet Res 33:2561, 1972 7. Labhsetwar AP: Effects of prostaglandin F 2" on some reproductive processes of hamsters and rats. J Endocrinol 53:201, 1972 8. Hubbard CJ, Bo WJ: The effect of the IUD and prostaglandin F 2 a on luteolysis in the pregnant hamster. Anat Rec 187:609, 1977 9. Krueger WA, Bo WJ, Garrison BM: Early uterine neutrophilic response to silk and polyethylene IUDs in the rat. Contraception 8:549, 1973 10. Bo WJ, Krueger WA, Bartley CM: The influence of chlorambucil on IUD-induced uterine neutrophils. Contraception 10:667, 1974 11. Bo WJ, Krueger WA, Sain LE: Effect of direct injection of neutrophils from uterine horns of rats containing intrauterine devices into recipient pregnant uteri. Fertil Steril 27:1318, 1976