Influence of human chorionic gonadotropin (hCG) and hCG internalization by granulosa cells on the rate of in vitro fertilization and embryonic development of human oocytes

Subpopulations of human granulosa-luteal cells obtained during early timed and during normally timed follicular aspiration in in-vitro fertilization-embryo transfer cycles

OBJECTIVE

To find the differences between human granulosa-luteal cells obtained during early timed follicular aspiration to prevent severe ovarian hyperstimulation syndrome (OHSS) and during normally timed follicular aspiration.

DESIGN

Retrospective analysis of clinical laboratory data.

SETTING

In vitro fertilization unit, University Department of Obstetrics and Gynecology, Ljubljana, Slovenia.

PATIENT(S)

Twenty women undergoing IVF-ET at high risk for OHSS.

INTERVENTION(S)

Cells were obtained from the follicles of women who were stimulated with hMG and hCG during an early timed follicular aspiration of one ovary, 10-12 hours after hCG, and during a normally timed follicular aspiration of the contralateral ovary, 32-36 hours after hCG administration.

MAIN OUTCOME MEASURE(S)

Subpopulations of granulosa-luteal cells were observed by computerized image analysis in which hCG was localized using immunoperoxidase staining.

RESULT(S)

Early timed follicular aspirates contained no oocytes and only a scant number of granulosa cells. Granulosa-luteal cells were smaller than those from normally timed follicular aspirates. We identified three subpopulations in early timed follicular aspirates: nonluteinized, small luteinized, and medium luteinized cells. In normally timed follicular aspirates, four subpopulations were identified, including large luteinized cells. The normally timed follicular aspirates contained more hCG-stained cells. Three staining types of hCG localization were found: on the surface membrane, on the surface membrane and within the cytoplasm, and only within the cytoplasm of cells from normally timed follicular aspirates. Early timed follicular aspirates contained only cells with membrane hCG localization.

CONCLUSION(S)

We found differences in morphometric characteristics and hCG localization between human granulosa-luteal cells obtained during early timed follicular aspiration to prevent severe OHSS and during normally timed follicular aspiration.

Subpopulations of human granulosa-luteal cells in natural and stimulated in vitro fertilization-embryo transfer cycles

OBJECTIVE

To find out the differences between human granulosa-luteal cells derived from natural and stimulated IVF-ET cycles.

DESIGN

Cells were obtained from dominant follicles of 52 women with natural cycles in whom preovulatory hCG was given when the follicle was mature and from 50 dominant follicles of women undergoing IVF-ET with hMG and hCG.

SETTING

In Vitro Fertilization Unit, University Department of Obstetrics and Gynecology Ljubljana, Slovenia.

MAIN OUTCOME MEASURE

Four subpopulations of cells were observed by computerized image analysis in which hCG was localized using immunoperoxidase staining.

RESULTS

The nonluteinized granulosa cells from natural cycles were larger than those from the stimulated ones. In luteinized cell types, there was no difference in cell area between natural and stimulated cycles. Three staining types of hCG localization were found: on the surface membrane, on the surface membrane and within the cytoplasm, and within the cytoplasm alone. The hCG stained cells from natural cycles were larger than the ones from stimulated cycles. The natural developing follicles contained more hCG stained cells than the stimulated ones. The follicles with fertilizable oocytes had more cells with cytoplasmic hCG localization. Only in natural cycles was there was a correlation between follicular fluid hCG levels and the percentage of the hCG stained cells.

CONCLUSION

We found differences in morphometric characteristics and hCG localization between human granulosa and granulosa-luteal cells obtained from natural and stimulated IVF-ET cycles.

Identification of follicles with fertilizable oocytes by sequential ultrasound measurements during follicular development

Patients undergoing ovulation induction for in vitro fertilization and embryo transfer (IVF-ET) were monitored daily with serum estradiol-17 beta (E2) and ultrasound. The location of each individual follicle was established by taking ultrasound images through serial sections of the ovary. The diameter of each follicle and the volume of its follicular wall (FW) were determined from ultrasound images using a computer-controlled image analyzer. A total of 44 follicles from nine patients was studied, with an overall fertilization rate of 46% In all patients, serum E2 levels increased prior to human chorionic gonadotropin (hCG). Whereas changes in either the average diameter or the volume of the entire follicle did not identify follicles with fertilizable oocytes, FW volume measurements were predictive. Prior to hCG, FW volume increased 24 +/- 8%/day in follicles with fertilizable oocytes but decreased 3 +/- 6%/day in follicles with nonfertilizable oocytes (P less than 0.05). Three major patterns of follicular development were observed for follicles with nonfertilizable oocytes: slow growing (less than 20% increase in FW volume), nongrowing (no change in the FW volume), and "degenerating" (a decrease in the FW volume), suggesting that these follicles are "postmature." These data demonstrate that FW volume measurements made from sequential ultrasound images provide an accurate method to identify those follicles that contain fertilizable oocytes.

Human chorionic gonadotropin localization and morphometric characterization of human granulosa-luteal cells obtained during in vitro fertilization cycles

The area and cytoplasmic-to-nuclear ratio (C/N) of cells aspirated from follicles with mature oocytes was determined using a computerized image analysis system. The presence of human chorionic gonadotropin (hCG) on the surface membrane and/or within the cytoplasm of each cell also was determined using a horseradish peroxidase immunocytochemical procedure. Based on morphometric characteristics, follicular cells were classified as granulosa or luteal. Granulosa cells were less than 75 micron 2 in area with a C/N of approximately 0.5. Luteal cells were classified as small (less than 75 micron 2, C/N approximately 1.5), midluteal (76 to 100 micron 2, C/N greater than 1.5) and large luteal (greater than 100 micron 2, C/N greater than 1.5). Compared with aspirates from follicles containing fertilizable oocytes, aspirates from follicles with nonfertilizable oocytes had fewer granulosa cells and more large luteal cells. HCG was localized on the membranes of granulosa and small luteal cells and within the cytoplasm of midluteal cells. Human chorionic gonadotropin was generally not observed on either the membranes or cytoplasm of luteal cells over 120 micron 2. These data support the concept that granulosa cells bind hCG to membrane receptors, internalize hCG, and begin to luteinize in response to hCG stimulation. Since the aspirates from follicles containing nonfertilizable oocytes possessed a higher percentage of large luteal cells, it is postulated that the cells from these aspirates began the luteinization process earlier than those from follicles containing fertilizable oocytes.