Ileal endometriosis: radiographic findings in five cases

PURPOSE

To determine the radiographic findings in five patients with ileal endometriosis.

MATERIALS AND METHODS

A search of radiology files revealed five patients with surgically proved endometriotic implants in the ileum at enteroclysis (three patients), at small-bowel follow-through (one patient), and at double-contrast barium enema study (one patient). The radiographic findings were reviewed retrospectively. Clinical, surgical, and histopathologic findings were also reviewed.

RESULTS

All five patients were nulliparous women (mean age, 34.4 years; age range, 28-41 years). Four patients presented with abdominal and/or pelvic pain, but only one of these four had cyclic pain that coincided with menstruation. Barium studies revealed endometriotic implants in the terminal ileum within 10 cm of the ileocecal valve in four patients and in the mid-ileum in one. The radiographic findings consisted of extrinsic mass effect with variable spiculation and tethering of folds in two patients, annular lesions with spiculated folds and abrupt or tapered borders in two, and a plaque-like lesion in one. In four patients who underwent double-contrast barium enema studies, associated endometriotic implants were found in the rectosigmoid colon.

CONCLUSION

Ileal endometriosis usually involves the terminal ileum within 10 cm of the ileocecal valve and manifests as a spectrum of findings on barium studies. Ileal endometriosis should therefore be considered when these findings are present in young, nulliparous women with abdominal or pelvic pain.

Uterine leiomyomas: histopathologic features, MR imaging findings, differential diagnosis, and treatment

Leiomyomas are the most common uterine neoplasm and are composed of smooth muscle with varying amounts of fibrous connective tissue. As leiomyomas enlarge, they may outgrow their blood supply, resulting in various types of degeneration: hyaline or myxoid degeneration, calcification, cystic degeneration, and red degeneration. Leiomyomas are classified as submucosal, intramural, or subserosal; the latter may become pedunculated and simulate ovarian neoplasms. Although most leiomyomas are asymptomatic, patients may present with abnormal uterine bleeding, pressure on adjacent organs, pain, infertility, or a palpable abdominalpelvic mass. Magnetic resonance (MR) imaging is the most accurate imaging technique for detection and localization of leiomyomas. On T2-weighted images, nondegenerated leiomyomas appear as well-circumscribed masses of decreased signal intensity; however, cellular leiomyomas can have relatively higher signal intensity on T2-weighted images and demonstrate enhancement on contrast material-enhanced images. Degenerated leiomyomas have variable appearances on T2-weighted images and contrast-enhanced images. The differential diagnosis of leiomyomas includes adenomyosis, solid adnexal mass, focal myometrial contraction, and uterine leiomyosarcoma. For patients with symptoms, medical or surgical treatment may be indicated. MR imaging also has a role in treatment of leiomyomas by assisting in surgical planning and monitoring the response to medical therapy.

Analysis of the human zona pellucida during culture: correlation with diagnosis and the preovulatory hormonal environment

PURPOSE

The objective of this study was to analyze sequentially the human zona pellucida changes in an in vitro fertilization program as it relates to several variables.

METHODS

The zona pellucida thickness was measured daily in zygotes and cleavage-stage embryos on a Nikon inverted microscope equipped with Hoffman modulation contrast optics, using an ocular micrometer. A total of 512 embryos from 96 patients was evaluated.

RESULTS

There was a highly significant direct correlation between zona thickness and preovulatory estradiol and basal day 3 FSH levels (P < 0.02 and P < 0.0006, respectively). This relationship showed a rapid reversal following 48 hr of culture; embryos from patients with the highest FSH levels had thinner zonae prior to transfer (P < 0.0007). The zonae from patients with unexplained infertility were thicker (19.4 +/- 2.7 microns) than those from patients with endometriosis (17.7 +/- 2.2 microns), tubal (17.5 +/- 2.4 microns), or male-factor infertility (16.4 +/- 2.7 microns) (P < 0.0001) on the first day of culture.

CONCLUSIONS

We hypothesize that the thickness of the human zona pellucida is influenced by the preovulatory hormonal environment and diagnosis. These factors should be considered as part of the embryo quality evaluation prior to transfer or when assessing the possibility of using assisted hatching. More studies are needed to understand the factors regulating the thickness of the human zona pellucida.

Sequential analysis of zona thickness during in vitro culture of human zygotes: correlation with embryo quality, age, and implantation

Zona pellucida thickness was measured daily in zygotes and cleavage stage embryos. Measurements were performed on a Nikon inverted microscope equipped with Hoffman modulation optics, using an ocular micrometer. Zona thickness of each zygote/embryo was measured four times, the zygote/embryo was then "rolled over," and four more measurements were repeated for a total of eight. The zygotes/embryos were photographed daily and the measurements repeated on the prints. Subsequently, the mean zona thickness for each stage was calculated. A total of 81 patients (mean age 33.8 +/- 4.2) participated in the study. A total of 427 embryos were evaluated. Categorical data differences between groups were evaluated by ANOVA and multiple linear regression. For nominal data, the Kruskal-Wallis test was applied; when P < 0.05 the differences were considered to be significant. We found that the average zona thickness on day 1 of in vitro culture was 17.7 +/- 0.14 microns; 16.3 +/- 0.14 microns on day 2 and 14.9 +/- 0.14 microns on day 3 (P < .0001). When the zona thickness was analyzed in relation to the number of blastomeres on day 3 of culture, there was a highly significant correlation with blastomere number (P < .0001). Similarly, there was a highly significant correlation with embryo grade (P < .005) and fragmentation (P < .001). The data were also analyzed for embryos transferred that resulted in a successful pregnancy, revealing that embryos in a pregnancy cycle had significantly thinner zonae pellucidae (P < .0001), when compared to embryos that were not transferred or from nonconceptual cycles. The average zona thickness also decreased with age, and was most apparent after 35 years. Changes in zona thickness correlated with the number of blastomeres, grade, fragmentation, age and were more evident in embryos transferred from cycles resulting in successful pregnancies. Therefore, zona pellucida measurements should be included in the overall assessment of embryo quality, since this information may be useful in the selection of optimal embryos for transfer.

Uterine arteriovenous malformation in a patient with recurrent pregnancy loss and a bicornuate uterus. A case report

BACKGROUND

Arteriovenous malformations (AVM) of the uterus are a rare but potential cause of recurrent pregnancy loss. Only four cases of uterine AVM have resulted in a live birth after conservative management. There is no previous report in which a combination of a müllerian anomaly and an AVM existed concomitantly.

CASE

A 33-year-old woman with a history of recurrent pregnancy loss was found to have a coexistent uterine AVM and a bicornuate uterus. The patient underwent arterial embolization and Strassman metroplasty and subsequently had a term pregnancy with a live birth.

CONCLUSION

Management of uterine AVM should be individualized, taking into account the patient's desire for future fertility and the stability of her health at presentation.

Effect of follicular size on oocyte retrieval, fertilization, cleavage, and embryo quality in in vitro fertilization cycles: a 6-year data collection

OBJECTIVE

To determine the effect of follicular size, including the size of the leading follicle, on oocyte retrieval, fertilization, cleavage, and embryo quality in IVF cycles based on a large data collection.

DESIGN

Retrospective analysis of 1,109 IVF cycles between 1987 and 1993 at the Hospital of the University of Pennsylvania including 606 patients ranging in age from 23 to 49 years.

RESULTS

Follicles with a volume < or = 1 mL show a significantly lower oocyte recovery rate than follicles with a volume of > 1 mL. The highest recovery rate (83.5%) was found in follicles with a volume of 3 to 4 mL. Above a follicular volume of 7 mL, the oocyte recovery drops below that observed for follicles between 1 and 7 mL. Fertilization and cleavage rates were also higher in oocytes obtained from follicles > 1 mL compared with follicles < or = 1 mL. Although fertilization rates were fairly stable above volumes of 1 mL, cleavage rates continued to rise to a peak percentage of 92% with volumes between 6 and 7 mL. Leading follicle size did not have an effect on fertilization and cleavage rates of cohort oocytes. Embryo quality was not influenced significantly by follicular volume.

CONCLUSION

Based on this evaluation of a large number of follicles, follicular size is a useful indicator of oocyte recovery, fertilization, and cleavage in IVF cycles. For optimal results, the follicular fluid volume in gonadotropin- and hCG-stimulated cycles should be > 1 mL, which corresponds to a follicle diameter of > 12 mm, and not larger than 7 mL (24 mm). For timing of hCG administration, the number of adequate size follicles appears to be more important than the size of the leading follicle(s).

Perioperative complications arising after transvaginal oocyte retrieval

OBJECTIVE

To determine the incidence of perioperative morbidity in patients undergoing transvaginal oocyte retrieval and to identify those patients at greatest risk for complications.

METHODS

A retrospective analysis was performed on 674 patients of reproductive age who underwent transvaginal retrieval of oocytes for assisted reproduction technologies during a 3-year period. All procedures were performed by surgeons with extensive experience with transvaginal retrieval. Patients were entered into the program with a primary diagnosis of unexplained infertility (16%), endometriosis (32%), pelvic adhesions and/or tubal occlusion (38%), or infertility from male or immunologic factors (14%).

RESULTS

Of the 674 patients studied, ten (1.5%) required hospital admission because of perioperative complications. Nine of these patients needed intravenous antibiotics and one required admission and observation for an expanding broad-ligament hematoma. Six of nine women admitted for antibiotic therapy had a history of extensive pelvic adhesions with or without a history of salpingitis. Five of nine patients had a history of salpingitis. In addition, two patients experienced impressive vaginal arterial bleeding during the procedure.

CONCLUSION

This study suggests that transvaginal retrieval may not be as innocuous as is often expressed and that the primary factor predisposing to perioperative morbidity is a history of previous pelvic inflammatory disease and/or adnexal adhesions.

Perinatal outcome of singleton pregnancies conceived by in vitro fertilization: a controlled study

To determine whether conception by in vitro fertilization and embryo transfer (IVF) predisposes to perinatal complications, the obstetric records of 54 women delivered of singleton pregnancies after conception by IVF were examined. Control women were matched for age, parity, race, year of delivery, diethylstilbestrol exposure and medical problems; another group of women who conceived after infertility treatment was matched in similar fashion. IVF patients showed a longer first stage of labor than previously infertile women, experienced a greater intrapartum blood loss than control or previously infertile women, and showed a trend toward a higher cesarean delivery rate than control women. The differences noted probably do not arise from the physiology of IVF, and although some differences are statistically significant, they are of minimal clinical significance. Singleton pregnancies arising after IVF should not be considered as high risk in the absence of other predisposing factors.

Repetitive ovarian response to gonadotropin stimulation in an in vitro fertilization program

The temporal changes of estradiol levels in 19 women undergoing ovulation induction for in vitro fertilization (IVF) and embryo replacement were described by a mathematical model. The model was analyzed for differences between treatment cycles of an individual woman and between cycles of different women. This model was also used to evaluate the results of IVF treatment. The variation between cycles within individuals was found to be less than that between different women. The parameters that describe this model were found to correlate with follicular growth but not with number of oocytes retrieved, fertilized or cleaved.

Follicular aspiration and in vitro fertilization associated with pelvic reconstructive surgery

Between August 1982 and May 1987, 103 patients underwent in vitro fertilization-embryo transfer (IVF-ET) in association with pelvic reconstructive surgery for infertility. Follicular stimulation was induced with clomiphene citrate and laparotomy scheduled day 12 to 15 of the menstrual cycle. Ultrasound measurements of follicular diameter and number of follicles were obtained on the day of human chorionic gonadotropin (hCG) administration, and laparotomy and ovum retrieval performed 36 hours later. Embryo transfer was performed 48 to 72 hours after insemination. Patients were treated postoperatively with intramuscular progesterone. In addition to evaluating the overall pregnancy rate, the outcome of patients having one or more follicles greater than or equal to 1.4 cm in mean diameter (group A) were compared to those in group B (no follicles greater than or equal to 1.4 cm in diameter). The number of oocytes obtained and the fertilization rate and polyspermic fertilization rate were not significantly different between groups; 10.1% of patients in group A conceived but no patient conceived in group B, yielding an overall pregnancy rate of 8.7%. These data suggest that physicians having IVF-ET at their disposal offer patients IVF during pelvic reconstructive surgery.

Emotional and psychosocial factors in follow-up of women after IVF-ET treatment. A pilot investigation

One hundred and fifty-six women who enrolled for treatment in an in vitro fertilization (IVF-ET) program were interviewed, 15 months (mean interval) after the last program contact. Perceptions of treatment stress, decisions about further treatment and the extent of resolution of the infertility crisis were investigated. Standard self-report instruments were used to assess emotional status, self-esteem and marital adjustment. The results showed that only about half the couples who did not achieve pregnancy had decided to terminate treatment. Resolution of infertility was significantly correlated with coping with infertility and with the decision to abandon treatment. Although most patients described treatment as extremely stressful, this did not itself result in emotional distress or dysfunction following treatment, and psychiatric syndromes were infrequent. A deeper understanding of the interactions of these identified factors would help all couples who confront unwanted infertility.

Comparison of ultrasonographic transurethral and laparoscopic guided oocytes retrieval

Fifty-eight patients who underwent in vitro fertilization (IVF) treatment were divided into two groups. In 28 patients, ultrasonically guided transurethral follicular aspiration was performed under light general anesthesia. In 30 patients, laparoscopic follicular aspiration was performed under general anesthesia. The mean age for both groups was similar. Follicular recruitment was achieved with human menopausal gonadotropin (hMG) or a combination of clomiphene citrate and hMG. In the ultrasonically guided aspiration group, 128 follicles were aspirated, with a 64% recovery rate (83 oocytes) and an 88.1% embryo transfer (ET) rate (67 embryos). Three (10.7%) intrauterine pregnancies were established in this group. In the laparoscopic group, 153 follicles were aspirated, with a 68.6% recovery rate (105 oocytes) and an 86.3% ET rate (82 embryos), with 4 (13.3%) intrauterine pregnancies established. Three patients had both procedures done; however, none conceived. There were no statistically significant differences between the two groups. Ultrasonically guided transurethral follicular aspiration should be considered as an alternative route for oocyte retrieval, especially when laparoscopy is contraindicated or when the ovaries are not accessible.

Follicular maturation parameters associated with the failure of oocyte retrieval, fertilization, and cleavage in vitro

Follicular maturation parameters predictive of decreased success in human in vitro fertilization were evaluated in 104 gonadotropin-stimulated cycles. Falling estradiol (E2) levels correlated with decreased fertilization (1.9 oocyte/cycle) and cleavage (1.4 oocyte/cycle), when compared with cycles with increasing E2 (2.4 and 2.1 oocyte/cycle, respectively). Likewise, polyspermic fertilization was higher in the former group. Falling E2 levels after human chorionic gonadotropin (hCG) administration correlated with similar trends. Delaying hCG (24 to 96 hours) relative to the last dose of gonadotropin did not affect the total number of oocytes fertilized per cycle. However, polyspermic fertilization and cancellation rates were higher. Leading follicles growing beyond 2.3 cm (determined by ultrasound examination) were associated with decreased recovery, fertilization, and cleavage, and increased polyspermic fertilization. We conclude that ultrasonography and E2 monitoring can predict decreased fertilization and cleavage and should also be monitored after hCG administration.

Fertilization and cleavage after reinsemination of human oocytes in vitro

The results of reinsemination of 150 morphologically mature oocytes that failed to fertilize within 15 to 20 hours after initial insemination were evaluated. Only 41 oocytes (27.3%) were fertilized after reinsemination, which is significantly lower than the percentage obtained after initial insemination (74%). However, the cleavage rate was not impaired significantly. Polyspermic fertilization was common (17 oocytes, 29.3%). A total of 64 oocytes were transferred. In 18 patients, all of the oocytes that were transferred had been reinseminated; none of these patients conceived. However, of 28 patients who received embryos arising from both initial insemination and reinsemination protocols, 7 conceived (25%). We suggest that the percentage of fertilization is impaired after 22 hours of incubation in vitro and that those oocytes that have fertilized after reinsemination might partly reflect a misjudgment of initial oocyte maturity. Nevertheless, reinsemination is a relatively simple procedure, with no known attributed risk. Therefore, we recommend reinsemination to increase the overall fertilization percentage. Additional studies are needed to establish better methods for assessment of oocyte maturity to evaluate properly the benefit of such reinsemination procedures.

Human chorionic gonadotropin and 8-bromo-adenosine 3',5'-monophosphate stimulate [125I]low density lipoprotein uptake and metabolism by luteinized human granulosa cells in culture

In nonsteroidogenic cells, cellular cholesterol requirements and sterol availability determine low density lipoprotein (LDL) receptor expression and LDL metabolism. We wished to learn if hCG and cAMP increase LDL metabolism by cultured luteinized human granulosa cells and whether this increase is dependent on enhanced metabolism of cellular cholesterol stores to steroid. Granulosa cells were cultured for 48 h in medium containing 20% human male serum and then for 48 h in serum- and hormone-free medium. The cells then received either fresh medium (no additions) or one of the following treatments: 500 mIU hCG/ml, 1.5 mM 8-bromo-cAMP, 100 micrograms aminoglutethimide (AG)/ml to inhibit cholesterol metabolism to steroid hormones, hCG plus AG, or 8-bromo-cAMP plus AG. After 6-48 h of exposure to tropic agents, specific metabolism of [125I]LDL was determined. hCG and 8-bromo-cAMP significantly increased (P less than 0.05) the amount of [125I]LDL bound (2.2-fold), internalized (2.3-fold), and degraded (2.9-fold) by the luteinized granulosa cells. The apparent Km values for LDL degradation in control and hCG-treated cells were similar (2.0 and 2.6 micrograms/ml, respectively). As little as 10 mIU hCG/ml stimulated LDL metabolism in a time-dependent fashion: a stimulatory effect was detected within 6 h of exposure to hCG and was greater after 24 h. AG attenuated but did not prevent the hCG- or 8-bromo-cAMP-stimulated increase in both LDL uptake and metabolism, although it completely inhibited the steroidogenic response. AG alone had no significant effect on [125I] LDL metabolism. We conclude that hCG and cAMP increase LDL metabolism by luteinized human granulosa cells. These effects are apparently not simply a consequence of enhanced cellular cholesterol metabolism to steroids.

Effects of prolactin on progestin secretion by human granulosa cells in culture

Concentrations of human prolactin (hPrl) greater than or equal to 600 ng/ml produced inhibition of progestin production in cultures of granulosa cells pooled from follicles of women stimulated with clomiphene citrate-human chorionic gonadotropin (hCG). However, cells collected from follicles of human menopausal gonadotropin (HMG)-hCG-treated patients did not demonstrate a significant reduction in progestin secretion in response to hPrl. We conclude that high concentrations of hPrl can result in inhibition of steroidogenesis, but the expression of the inhibitory effects of Prl depends upon the hormonal treatments used to stimulate follicular growth.

The effect of immunoglobulin occurring on human sperm in vivo on the human sperm/hamster ova penetration assay

We selected 91 infertile men who were tested for increased sperm-associated immunoglobulin and also tested in the human sperm/hamster ova penetration assay. There was a statistically significant association between the presence of increased sperm-associated IgG alone (p = 0.0218) and both sperm-associated IgG and A (p = 0.0187) when correlated with the failure to penetrate any hamster ova. There was a trend but no statistical significance when sperm-associated immunoglobulin A alone was present. There was a trend but no statistical relationship between the presence of sperm-associated immunoglobulin and the sperm penetration assay when the criteria for normality of the sperm penetration assay was a 15% or greater ovum penetration rate.

The zona-free hamster egg penetration assay as a prognostic indicator in a human in vitro fertilization program

The present study was designed to test the validity of the hamster egg penetration assay as a prognostic indicator of male fertility in 54 patients undergoing in vitro fertilization. Human oocyte fertilization, cleavage, and pregnancy were compared with the results of this bioassay. Good correlation was found between hamster egg penetration and oocyte fertilization. Conversely, a definite lower limit of hamster egg penetration to define absolute male infertility could not be established because human oocyte fertilization, cleavage, and even pregnancy occurred in spite of low hamster egg penetration.

Simultaneous ectopic pregnancy with intrauterine twin gestations after in vitro fertilization and embryo transfer

A simultaneous ectopic tubal pregnancy with viable intrauterine twin gestations after IVF-ET of five fertilized eggs is presented. Pelvic ultrasound and serial quantitative hCG levels were not helpful in the diagnosis of the tubal pregnancy. The risk of multiple pregnancies and of concomitant intrauterine and extrauterine gestations increases with transfer of a greater number of embryos. Karyotype of the tubal pregnancy was normal (46,XX).

Submucosal leiomyomas and infertility

Seventeen patients with primary (59%) or secondary (41%) infertility and evidence of at least 1 large (greater than or equal to 5 cm) submucosal leiomyoma underwent abdominal myomectomy . In all patients, no other cause of infertility could be found. Following surgery, 2 of the 17 patients elected to use contraception. Thirteen of the 15 patients wishing to establish a pregnancy had 10 or more months of sexual exposure. The overall pregnancy rate was 47%, and 53% of those patients attempting to establish a pregnancy conceived. The corrected pregnancy rate for those with adequate sexual exposure for at least 10 months was 61.5%. Of those women who attained a pregnancy, 63% did so within 11 months after surgery. Only one patient conceived after more than 3 years (38 months). These results suggest that submucosal leiomyomas are a possible cause of infertility and are highly amenable to surgical treatment and subsequent restoration of fertility.

Stimulation of progesterone synthesis in luteinized human granulosa cells by human chorionic gonadotropin and 8-bromo-adenosine 3',5'-monophosphate: the effect of low density lipoprotein

Primary cultures of luteinized human granulosa cells reduced progestin secretion when taken from serum- and gonadotropin-containing medium into serum- and hormone-free medium. When added individually hCG, 8-bromo-cAMP and low density lipoprotein (LDL) stimulated progestin secretion by the cells after they spent 48 h in serum- and hormone-free medium. However, combinations of hCG or 8-bromo-cAMP and LDL were most effective in increasing steroidogenesis. The effects of hCG in enhancing steroidogenesis in the presence of LDL were first detectable after 3 h, but were most marked after 20 h of culture. hCG and 8-bromo-cAMP increased the conversion of [3H]cholesteryl linoleate, which had been incorporated into the core of LDL, into [3H]progesterone. hCG also stimulated cellular accumulation of LDL cholesterol, as assessed by incorporation of [1-14C]oleic acid into sterol esters or by measurement of total cellular cholesterol in the presence of amino-glutethimide to block steroidogenesis. In contrast to progesterone secretion, estradiol secretion was not affected by the addition of LDL in the absence or presence of 8-bromo-cAMP. We conclude that LDL cholesterol is required for maximal rates of progestin synthesis by human luteinized granulosa cells. When granulosa cells are stimulated by hCG, uptake of LDL cholesterol is promoted, and there is increased utilization of LDL cholesterol for steroid synthesis.

The role of lipoproteins in steroidogenesis by human luteinized granulosa cells in culture

Progesterone secretion by primary cultures of luteinized human granulosa cells was markedly reduced when the cells were incubated in lipoprotein-deficient medium. Addition of LDL, but not HDL3, to cells cultured in lipoprotein-deficient medium stimulated progestin secretion. The effects of LDL were dose-dependent and saturable (Km = 5.5 micrograms LDL protein/ml). LDL also stimulated [3H]-oleate incorporation into cellular sterol esters, with half maximal stimulation occurring at LDL concentrations of 10 micrograms protein/ml. The cultured cells bound and internalized [125I]-LDL in a dose dependent and saturable manner (Km = 5-10 micrograms LDL protein/ml). [125I]-LDL uptake was specific in that unlabeled LDL, but not unlabeled HDL3, competed with labeled LDL for uptake [125I]-HDL3 was also taken up by the cells, but by a lower affinity mechanism. We conclude that luteinized human granulosa cells utilize LDL-carried cholesterol for progestin synthesis, and that LDL is taken up via a specific, high affinity process.

Progesterone synthesis by luteinized human granulosa cells in culture: the role of de novo sterol synthesis and lipoprotein-carried sterol

Human granulosa cells cultured in the presence of estradiol, FSH, and LH secreted relatively little progesterone during the first 3-5 days of culture. The cells then underwent a morphological transformation associated with a 10-fold or more increase in progestin production. Cells not cultured with the tropic hormones usually produced progestin at a lower rate. Serum was required for the expression of maximal steroidogenic activity. Inhibitors of de novo sterol synthesis, ML-236B and 5-cholesten-3 beta,25-diol, did not affect progestin secretion by luteinized cells cultured in 20% serum, but these inhibitors did reduce [14C]acetate incorporation into sterols by 90%. ML-236B also did not affect hCG-stimulated progesterone secretion by the cells. However, when the cells were changed into lipoprotein-deficient medium, progestin production was markedly reduced within 24 h. The addition of low density lipoproteins (LDL) to the culture fluid restored progestin production, whereas high density lipoproteins tended to further inhibit steroid secretion. The effects of LDL on steroidogenesis were dose dependent and saturable. We conclude that luteinized human granulosa cells use LDL-carried sterol as the primary substrate for steroidogenesis.

Regulation of cholesterol acquisition and utilization in the corpus luteum

In this report we have focused on two aspects of control of corpus luteum function; the regulation of lipoprotein uptake and the modulation of cholesterol side chain cleavage through alterations in the phospholipid milieu. Until recently, a role of gonadotropins in the acquisition of lipoprotein-carried cholesterol had not been generally appreciated. However, it is likely that the regulation expression of cell surface lipoprotein receptors will prove to be an important function of tropic hormones, particularly LH, since luteal cells generate progestins at a substantial rate and must, therefore, have an equally substantial supply of cholesterol. Factors other than gonadotropins may have a function in control of lipoprotein receptors and it would not be surprising if luteolytic factors, such as prostaglandin F2 alpha, are found to diminish lipoprotein-uptake as part of their action in reducing steroidogenesis. The control of mitochondrial pregnenolone synthesis by gonadotropin-induced alterations in phospholipid composition of mitochondrial membranes represents a novel concept. Whether certain polar lipids will emerge with the status of intracellular messengers remains to be seen. In any event, our observations clearly demonstrate the possibility for such a mechanism of control.