Total Lordosis Research Articles

Answer to the Letter to the Editor concerning “4- and 5-level anterior fusions of the cervical spine”

Answer to the Letter to the Editor concerning “4- and 5-level anterior fusions of the cervical spine”

Characterizing the Shape of the Lumbar Spine Using an Active Shape Model

Analysis of positional magnetic resonance images of normal volunteers. To compare the reliability and precision of an active shape model to that of conventional lordosis measurements. Characterization of lumbar lordosis commonly relies on measurement of angles; these have been found to have errors of around 10 degrees . T2 weighted sagittal images of the lumbar spines of 24 male volunteers in the standing posture were acquired using a positional magnetic resonance scanner. An active shape model of the vertebral bodies from S1 to L1 was created. Lumbar lordosis was also determined by measuring the angles of the superior endplates. All measurements were performed twice by one observer and once by a second observer. The shape model identified 2 modes of variation to describe the shape of the lumbar spine (mode 1 described curvature and mode 2 described evenness of curvature). Significant correlations were found between mode 1 and total lordosis (R = 0.97, P < 0.001) and between mode 2 and mean absolute deviation of segmental lordosis (R = 0.80, P < 0.001). Intra- and interobserver reliability was higher for the shape model (intraclass correlation coefficients, 0.98-1.00) than for the lordosis angle measurements (intraclass correlation coefficients, 0.68-0.99). The relative error of the shape model (mode 1 = 4%; mode 2 = 9%) was lower than the conventional measurements (total lordosis = 10%). The shape of the lumbar spine in the sagittal plane can be comprehensively characterized using a shape model. The results are more reliable and precise than measurements of lordosis calculated from endplate angles.

Das laterale Profil der Lendenwirbelsäule nach lumbosacraler Spondylodese - Vergleich zwischen Harringtonstäben und einem transpedikulären Fixationssystem (USIS nach Zielke)

We compared the lateral profile of the lumbar spine after lumbosacral dorsal fusion in two groups of each 32 patients with comparable age, sex distribution and indication; one group had been fused with the use of two short Harrington rods, the other with the Universal Spinal Instrumentation System (USIS) according to Zielke/Harms. The sparing of motion segments using a transpedicular system is demonstrated by the average number of 1.7 fused motion segments compared to 2.2 with the Harrington rods. The average increase of cyphosis of the fused area could be reduced with USIS from 7.3 to 3.0 degrees in spite distraction. The greatest difference could be seen in cases of spondylolisthesis (2.0 degrees compared to 8.2) and in fusions including three segments (2.0 versus 7.0). No significant difference in total lordosis of the lumbar spine could be evaluated and there was no influence of preoperative mobility on the grade of postoperative cyphosis. The early results of lumbar fusion using USIS are clinically satisfying in spite of a relative high rate of rod fracture. measures to achieve a higher stability and diminish the rate of implant failure are discussed.

Knee – spine syndrome: correlation between sacral inclination and patellofemoral joint pain

AbstractLow back pain is an enormous clinical and public health problem. When we use spinal instrumentation, measurementsof spinal and leg alignment in the standing position are thought to be important. Knee joint pain has also become an enormous clinical problem in the increasing elderly population.However, the correlation between spinal alignment,particularly sacral inclination, and knee joint pain is not clear. We examined the correlation between lumbar lordosis, sacral inclination, and patellofemoral joint pain in elderly subjects. Three hundred and ninety-nine people aged 50–85 years were examined. Clinical findings and physical status were determined. Measurements and determination of total lordosis from L1 to S1 and sacral inclination were made from standingradiographs. The knee joints were evaluated by using the standing knee flexion angle, radiographs, and the patellofemoral (PF) joint grinding test. Thirty-nine percent of subjects were excluded because they had definite osteo-arthritis at the femorotibial joints. Fifty-eight percent of the subjects had felt low back pain within the previous 3 months, and 16% of the subjects complained of PF joint grinding pain. Sixteen percent of the subjects showed knee flexion when standing. There was asignificant difference in sacral inclination between the groups with and without PF joint grinding pain (P < 0.01). Sacral inclination was approximately 5° less in the knee flexion group. A correlation between sacral inclination and PF joint pain is defined, and its prevalence in the elderly is reported. We speculate that this phenomenon is caused by changing of lumbar alignment. In addition, we think this is a new pathological concept that we call the knee – spine syndrome.

Epidemiology of low back pain in the elderly: correlation withlumbar lordosis

We carried out an epidemiologic study to determine the prevalence of low back pain in elderly Japanese and to examine the correlation with lumbar lordosis in sagittal planeradiographs. Low back pain is an enormous clinical and public health problem. With the increasing use of spinal instrumentation, the measurement of lumbar lordosis is thought to be important. However, in elderly Japanese, the prevalence of low back pain and its correlation with lumbar lordosis is not clear. Five hundred and nine people, aged 50–85 years, were examined, and 489 subjects met our criteria. Clinical findings, physical status, and the visual analogue scale (VAS) of pain were examined in these subjects. Measurements and determination of total lordosis from L1-S1 were made from standing radiographs. Forty-eight percent of the subjects had experienced low back pain within the previous 3 months. Women had low back pain more frequently (P=0.006).There was a significant difference in lumbar lordosis between the groups with and without low back pain (P=0.0006).Lumbar lordosis was approximately 4° less in the low back pain group and there was no relationship to age or sex in either group. VAS was significantly inversely correlated with lumbar lordosis (P=0.025, at rest). The body mass index (BMI) of the low back pain group was higher in women, but the difference was not significant (P=0.06). In conclusion, lumbar lordosis was defined and its prevalence in elderly Japanese was reported together with VAS and physical data used to compare the two groups.

Effect of wide posterior release on correction in adolescent idiopathic scoliosis.

Wide lumbar posterior release, consisting of partial excision of spinous process, excision of interspinous ligament and ligamentum flavum, and excision of facet in plane of facet from both outside and within the spinal canal has been employed to increase coronal correction and improve the production of lumbar lordosis (10). Adolescent idiopathic patients with fusion into the lumbar spine were studied. Pre- and postsurgical coronal and sagittal Cobb measurements as well bending measurements were done. Intraoperative biplanar radiographs were done after positioning, after lumbar rod placement, and finally after wide release and placement of the same rod. Statistical analysis was by paired Student's t-test. Significantly (p < 0.005), improved correction was attained in the coronal plane with release (76% vs. 64%). Total lordosis and instrumented segment lordosis was also significantly (p < 0.025) improved with release (12 degrees vs. 3 degrees). Coronal and sagittal plane correction in the lumbar spine is improved significantly with a wide posterior lumbar release.

The Effect of Operative Position on Lumbar Lordosis

Study Design. The effect of intraoperative positioning on lumbar lordosis was retrospectively studied by radiographic analysis of 40 patients under general anesthesia. Objectives. The aim of this study was to document changes in segmental and total lumbar lordosis between preoperative standing and intraoperative radiographs taken in the “90-90” and prone positions. Summary of Background. Preservation of physiologic lordosis was an important consideration in reconstructive lumbar spine surgery. To avoid iatrogenic loss of lordosis when using spinal instrumentation and to facilitate decompressive procedures, it was necessary to understand how segmental alignments were affected by intraoperative positioning. Although many positioning techniques were used, the effect on lumbar lordosis was not well established. Methods. Preoperative (standing 36″ lateral spine) and intraoperative radiographs (lateral lumbar spine L1 to the sacrum) in either the “90-90” position on a Hastings frame (n = 20) or the prone position on a Jackson table (n = 20) were measured twice by two independent observers using Cobb methodology for total and segmental lordosis between L1 and S1. Data were analyzed for intra- and interobserver reliability and changes in segmental and total lordosis between standing and intraoperative radiographs. Results. Analysis of intra- and interobserver reliability revealed measurements were accurate and reproducible. The “90-90” position produced significant loss (P ≤ 0.01) of total and segmental lordosis at all levels except L1-L2, which showed no change. Segmental lordosis was reduced nearly 60% at L2-L3, L3-L4, and L4-L5, and total lordosis was reduced by more than 35%. The prone position on the Jackson table increased segmental lordosis at L5-S1 by 22% (P ≤ 0.01) and preserved total and segmental standing lordosis at all other levels. Conclusions. The “90-90” position on the Hastings frame was associated with significant reduction of total and segmental lordosis in the middle and lower lumbar spine. Positioning prone on a Jackson table maintained standing lumbar lordosis and increased lumbosacral lordosis.

5α-reduced progesterone metabolites are essential in hamster VTA for sexual receptivity

Progesterone's (P) actions in the ventral medial hypothalamus (VMH) and the ventral tegmental area (VTA) are essential for sexual receptivity in hamsters. This study investigates the notion that P works in the VTA in the absence of intracellular P receptors (PRs) by 5α-reduction to progestins, which would subsequently bind to membrane γ-Aminobutyric Acid receptor complexes (GBRs). To test the importance of P metabolism, a 5α-reductase inhibitor, 17β-N, N-diethylcarbamoyl-4-methyl-4aza-5α-androstan-3-one (4MA) was administered SC (0, 3, 9, 15, 24, or 30mg/kg) to ovx estradiol benzoate(EB)-primed hamsters, followed by one of six doses of SC P (0, 25, 50, 100, 200, or 500μg) and sexual receptivity testing. 200μg P-treated animals administered higher (24 and 30 mg/kg) doses of 4MA had significantly decreased total lordosis durations (TLDs) compared to 0 mg/kg 4MA controls (exp 1). In exp 2, 4MA was aimed bilaterally at the VTA prior to SC P. After 200μg P, animals had significantly lower TLDs than after 500μg P, 3 hours following bilateral VTA implantation of 4MA, but not cholesterol. In exp 3, cycling female hamsters were infused with 1.0μg 4MA or vehicle unilaterally into the VTA on diestrus, proestrus, and estrus. 4MA, but not vehicle, infusions into the VTA interrupted receptivity in estrus and proestrus animals, but had no effect on diestrus animals. 4MA's reduction of receptivity when given systematically and intracranially strongly supports the hypothesis that 5α-reduced P metabolites, possibly interacting with GBRs in the VTA, are essential for sexual receptivity in hamsters.

Muscimol facilitates sexual receptivity in hamsters when infused into the ventral tegmentum

Progestogenic stimulation of both the ventral medial nucleus of the hypothalamus (VMH) and the ventral tegmental area (VTA) within the midbrain is critical for normal receptivity in female hamsters. However, few estrogen-induced progestin receptors have been found in the midbrain. In addition, recent evidence suggests that progestin's action in the VTA is mediated nongenomically at the membrane. The present experiment investigated the possible role of GABAA receptors in mediating the effects of progesterone in this brain region. Ovariectomized female hamsters were bilaterally implanted with chronic cannulae aimed toward the ventral mesencephalon. Five days after surgery, animals were injected with 10 μg estradiol benzoate SC. Forty hours later, the same animals were injected with either 25 or 100 μg progesterone and at hour 43.5, 50 ng muscimol was infused in 0.5 μl. Control animals received 0.5 μl vehicle, sterile saline, or no infusion. At hour 44, animals were tested for sexual receptivity by placing them in an observation arena with a sexually experienced male for 10 min, during which lordosis duration was recorded. The following week, the same regimen was given with the alternate dose of progesterone. Histology revealed that only those animals that were infused with muscimol into the VTA had total lordosis durations that were significantly longer than the controls. Implants that missed the ventral tegmental area were much less effective. These results indicate that GABA might play a facilitatory role in enhancing the efficacy of threshold doses of progesterone. Whether this interaction is due to a direct effect of progestins on the GABAA receptor complex awaits further study.

Intravenous administration of progesterone and the onset of receptivity in female hamsters

Progesterone-facilitated receptivity is believed to be a genomically mediated event. However, in contrast to estrogen, progesterone's effects occur rapidly. This experiment was designed to examine the temporal onset of receptivity in hamsters following intravenous (IV) administration of progesterone. Ovariectomized female hamsters were tested for their responsiveness to 10 μg estradiol benzoate (EB) plus 0, 50, or 200 μg progesterone, administered subcutaneously (SC). The hamsters were tested for sexual receptivity at 0.5, 1, 1.5, 2, 3 and 4 h. Three days later they were fitted with jugular catheters. Two days after catheter implantation they received 10 μg EB SC; 48 h later they were tested for receptivity and then received an IV injection of 0, 50, or 200 μg progesterone in 0.2 ml propylene glycol. Following the IV P injection the animals were again tested at 0.5, 1, 1.5, 2, 3 and 4 h. Progesterone administration (either SC or IV) resulted in an increase in total lordosis duration (TLD) over time. TLD had significantly increased from the pre-progesterone levels by 2 h after 50 μg progesterone IV. In contrast, 50 μg progesterone SC did not cause an increase in TLD until 3 h postinjection. Moreover, in comparison to SC administration, the effects of IV progesterone were short-lived; TLD was significantly decreased by 4 h after injection. Following 200 μg progesterone, the latency to respond was shorter than with 50 μg progesterone (1.5 vs. 2 h). There was no difference in the onset of receptivity as a function of route of administration at the 200 μg dose. These results demonstrate that the minimum latency for the behavioral effects of progesterone is longer in hamsters than has been found in rats. This may reflect species differences in the neurochemical mechanisms of progesterone action.

Blockade of lordosis by androst-1,4,6-triene-3,17-dione (ATD) and tamoxifen in female hamsters primed with testosterone propionate

Normal female hamsters display lordosis after testosterone propionate (TP) plus progesterone (P) treatments. Such effect is probably mediated through aromatization of testosterone (T) into estradiol. If so, then an aromatase inhibitor (ATD) or an estrogen antagonist (tamoxifen, TAM) should be able to block the activational effect of T on lordosis. To test this hypothesis, 48 ovariectomized female hamsters were assigned into six groups which, according to treatments received, were ATD + TP, TAM + TP, OIL + TP, ATD + EB (estradiol benzoate), TAM + EB, and OIL + EB groups. The groups received assigned treatments for 2 days and were injected with P on the third day. Five minutes of behavior test was conducted 4 hr after P injection. The OIL + TP, OIL + EB, and ATD + EB groups all had averaged total lordosis duration (TLD) longer than 200 sec. The TLD of the TAM + EB group was only 117 sec. The ATD + TP and TAM + TP groups showed almost no lordosis. The results showed that the estrogen antagonist (TAM) impaired lordosis no matter whether the animals were primed with TP or EB, but the aromatase inhibitor (ATD) blocked lordosis only in TP primed females. It is concluded that the aromatization of T to estrogen is required for testosterone activation of lordosis in female hamsters.

Cholinergic regulation of sexual behavior in female hamsters

The effect of cholinergic manipulations on sexual behavior in female hamsters was determined in a series of experiments. The cholinergic receptor antagonist, scopolamine, reduced total lordosis duration following systemic (1 mg/kg) or intraventricular (10 and 20 μg bilaterally) administration to ovariectomized hamsters primed with estrogen and progesterone. The inhibitory effect of scopolamine on lordosis occurred within 15 min after either treatment route and persisted at 2 hr after systemic administration. Intraventricular administration of the acetylcholinesterase inhibitor, physostigmine (10 μg bilaterally), activated lordosis of short duration in ovariectomized hamsters primed only with estrogen. These results indicate that the cholinergic system plays a facilitative role in the regulation of sexual behavior in female hamsters similar to that demonstrated previously in female rats. The activational effect of cholinergic neurotransmission on female sexual behavior may be a neural mechanism common to a number of mammalian species.

Analysis of Lumbar Lordosis in Posterior Spine Fusions for Idiopathic Scoliosis

Previous reports are inconclusive regarding changes in the lumbar region after Harrington rod distraction and posterior spinal fusion for idiopathic scoliosis. The purpose of this study was to evaluate the effects of spinal fusion on the lumbar region, particularly the overall lumbar lordosis, the lumbar lordosis in and below the fused segment, the sacro-horizontal angle, and the sagittal plane alignment of the spine. Sixty-six patients under 21 years of age with idiopathic scoliosis who had spine fusion extending to the lumbar vertebrae using only Harrington distraction instrumentation were evaluated. The total lordosis, sacro-horizontal angle, and sagittal plane alignment remained relatively constant. The lordosis within the fusion decreased, and lordosis caudal to the fusion, including the last fused vertebra, increased as the lower hook placement site moved caudally.

Effect of novel and familiar mating partners on the duration of sexual receptivity in the female hamster

The lordosis duration of the female golden hamster (Mesocricetus auratus) in response to novel and familiar mating partners was examined. In Experiment 1, females mated to the point of sexual satiation with one male hamster, and following its removal, showed renewed receptivity in response to the introduction of a second male. Upon sexual satiation with the second male, females either received a novel third male or were reexposed to the original male. Total lordosis duration in the third bout in the group receiving a novel male was significantly greater than in the group reexposed to the original male. In Experiment 2, the insertion of a 1-h delay between the second and the third mating partner had no effect on the female's responsiveness, regardless of whether the third male was the original male or a novel male. In Experiment 3, removal of the ovaries followed by hormone replacement treatment (40 micrograms estradiol benzoate, 72 h prior to testing, and 500 micrograms progesterone, 4 h prior to testing) failed to alter the females' ability to discriminate between novel and familiar mating partners. These results demonstrate that females make clear discriminations among individual mating partners, that this can affect sexual receptivity and will continue to do so following a delay of at least 1 h, and that the effect is not mediated by the release of ovarian steroids.

Female sexual behavior in the golden hamster following kainic acid lesions in the lateral septal area

Patterns of female sexual behavior in the hamster are qualitatively different from that observed in the rat. Hamsters demonstrate tonic immobility and a sustained lordotic response that can last for several minutes following minimal stimulation from the male while in rats, the lordotic response is highly depedent upon continued stimulation from the male and lasts for only a few seconds following a mount or intromission. Also, the hamster requires both estrogen and progesterone priming in order to display female sexual behavior but the rat can show lordotic behavior following treatment with estrogen alone. Electrolytic lesions in the lateral septal area of female rats produce a facilitation in female sexual behavior and increase behavioral sensitivity to estrogen. However, lesions in the lateral septal area of rats produced by the neurotoxin kainic acid (KA) result in deficits in female sexual behavior following estrogen and progesterone treatment. Given these species differences in sexual behavior, we have examined the effects of KA lesions in the lateral septal area of hamsters on female sexual behavior. Adult female golden hamsters were ovariectomized and tested for female sexual behavior prior to receiving brain surgery. For all behavior tests, animals were injected SC with 60 μg of estradiol benzoate/kg per day for two days and 0.5 mg of progesterone three hours prior to the behavior test on day three. Behavior tests consisted of placing the test animal in a male's home cage for 10 minutes and recording the latency to the first lordosis, length of the longest single bout of lordosis and total lordosis duration. Either KA (0.375 μg in 0.5 μl) or saline (control) were infused bilaterally into the lateral septal area. All animals were tested again for female sexual behavior at one and three weeks following brain surgery. There were no differences between the lesion and control groups for the pre-lesion behavior tests and the performance of the sham operated animals was comparable between the post- vs. pre-lesion tests. However, following brain surgery, the KA lesioned animals were significantly different from the sham operated controls on all behavioral measures. The KA lesioned animals showed significantly longer latencies to the first lordosis, significantly shorter single bouts of lordosis and significantly shorter total duration of lordosis for both behavior tests, relative to the controls. Thus, despite the large species differences in the display of female sexual behavior between rats and hamsters, KA lesions of the lateral septal area produce a similar deficit in female lordotic behavior. Thus, in addition to the known inhibitory role of the septal region, this brain area also exerts facilitatory control on female sexual behavior in both rats and hamsters.

Effects of progesterone on lordotic responses to specific mating stimuli in hamsters

Mating-induced inhibition of sexual receptivity was examined in ovariectomized, estrogen (E) treated and estrogen plus progesterone (E+P) treated hamsters given 10 min of exposure to male mounting stimulation alone or to mounts, intromissions, and ejaculations at eight hourly intervals. In E+P treated females, no differential effects of exposure to full mating stimulation vs. mounting stimulation alone were observed. In contrast, females given E treatment alone showed a marked differential response. Fully mated, E-treated females showed more lordosis than E-treated females exposed to mounts alone during the initial test. However, total lordosis duration declined precipitiously in the fully mated group by 2 hr and remained significantly below that in other groups during subsequent tests. Levels of receptivity in E-treated females mounted-only remained relatively constant until 8 hr. These results suggest that P reduces the inhibitory effects of vaginocervical cues received during mating without affecting the response to mounting stimulation alone. In addition, vaginocervical stimulation may initially facilitate lordosis in E-treated females.

Female regulation of mating location and acceptance of new mating partners following mating to sexual satiety: The coolidge effect demonstrated in the female golden hamster

All female hamsters mated to sexual satiety with a single male, accepted a different male, and showed receptivity again. While the total lordosis duration and the length of the longest bout of lordosis were both significantly shorter with male 2 than male 1, receptivity was of sufficient duration for both males 1 and 2 to mate to satiety. Most females accepted a third male and a few females accepted a fourth male. With males 3 and 4, receptivity was terminated before the males could mate to satiety. Reintroduction of a male with which the female had previously mated did not result in a renewal of receptivity. Female hamsters adapted to a home area show a significant preference for mating in this area with 88% of lordosis time occurring in the female's area. Female hamsters clearly show the “Coolidge effect” described for males, in which a novel stimulus leads to a renewal of sexual activity in the sexually satiated animal. In the female hamster the effect is very robust with the renewed mating resulting in a doubling of the total lordosis time over that found when mating occurs with a single male. Acceptance of multiple male partners is biologically advantageous as an insurance against the possible sterility of a single partner.

Effect of neonatal intrahypothalamic testosterone implants on cyclicity and adult sexual behavior in the female hamster.

To localize the neural sites of hormone action for sexual differentiation in the hamster, pellets containing 3 microgram testosterone were implanted directly in the preoptic area-anterior hypothalamus (POA-AH) and the ventromedial hypothalamus-arcuate regions of the hypothalamus of 3-day-old female hamsters. The POA-AH implants strongly enhanced the potential for ectopic mounts, rear mounts, and intromission patterns after adult testosterone treatment. 50% of the females with neonatal POA-AH implants demonstrated vaginal acyclicity in adulthood, suggesting a significant disruption of normal gonadotropin release. Tests for female sexual behavior revealed that implants in both POA-AH and ventromedial arcuate had no significant effect on latency to lordosis or total lordosis duration with estrogen and progesterone priming, but did reduce the longest single bout of lordosis. In conjunction with other recent investigations, these findings suggest that in the hamster, as in other species, androgenization involves several independent processes in terms of both location and sensitivity to hormone exposure.

Uncoupling of the sexual receptivity (lordosis) hormone relationships by estradiol benzoate and testosterone propionate injection in neonatal hamsters of both sexes

(1) Estradiol benzoate (EB) at 250 μg when injected into hamsters at 12, 24, 48, 72, 96 or 120 hr after birth was equally effective at all times in suppression of sexual responsiveness measured as total lordosis duration (TLD) per 10 min test interval. (2) Testosterone propionate TP at 500 μg resulted in a significantly greater suppression in TLD when injected at 12, 24 or 48 hr as compared with injections at 72, 96 or 120 hr. (3) All neonatally injected female groups showed a significant reduction in TLD scores when compared with nontreated females with the exception of 96 hr TP treated females. (4) None of the neonatally treated male groups had TLD scores which were significantly different from the nontreated males. (5) All groups of treated females showed lordosis which in the 12- and 24-hr treatment groups did not change significantly as a result of castration or exogenous hormone treatment. (6) The 48-hr TP-treated females were the earliest treatment group in which the TLD score decreased significantly following ovariectomy and increased significantly following treatment with exogenous estrogen and progesterone. (7) Facilitation of lordosis followed by inhibition of lordosis on repeated progesterone injection (biphasic response) was not seen in hamsters of either sex injected with EB between 12 and 120 hr after birth. (8) The noninjected male hamsters and hamsters of both sexes receiving TP treatment at 96 hr or later showed a biphasic response to progesterone. (9) Our observations indicate that defeminization is most readily produced by estrogen treatment which in turn suggests that aromatization of androgen to estrogen is important for defeminization. (10) Since male hamsters respond to estrogen and progesterone, although with lower TLD scores than found for females, the male hamster is only partially defeminized either as a result of low androgen production and/or aromatization enzymes available during the critical stages of development.

The effect of hysterectomy on hormone-induced lordosis behavior in hamsters

Ovariectomized-hysterectomized (OH) and ovariectomized-sham hysterectomized (OSH) hamsters were tested for lordosis behavior following treatments including either 1, 5, or 10 μg estradiol benzoate (EB) in combination with 0.1, 0.25, and 0.5 mg progesterone. Few animals responded at the 1 μg dose of EB and there were no differences in latency to the first display of lordosis or in the total lordosis duration among responding animals in the 5 and 10 μg EB groups. However, there was significantly more positive tests in the OSH group injected with 5 μg EB than in the OH group and this difference approached statistical significance in the 10 μg EB groups. The results are compared to similar studies in rats and possible mechanisms for the effects of hysterectomy are discussed.