Quantitative echotexture analysis of bovine corpora lutea

[Sonographic studies on the significance of follicle size and corpus luteum morphology in dairy cows after insemination]

OBJECTIVE

In dairy cattle, numerous factors determine the success of an insemination. The aim of the present study was to generate findings concerning the association between the preovulatory follicles, the corpora lutea with or without cavities and pregnancy in dairy cows under field conditions.

MATERIAL AND METHODS

Data was obtained from 176 dairy cows scheduled for artificial insemination. The cows were gynecologically examined using sonography at the time of insemination, 24 hours later, on day 9, on day 34 and after day 42 after insemination. Additionally, blood samples were collected from the coccygeal vein at the time of insemination and on day 9 in order to determine blood progesterone level.

RESULTS

Depending on the result of the pregnancy test, no difference was detected between the dimensions of the follicles, corpora lutea as well as their cavities and progesterone levels 9 days after insemination in the dairy cows with spontaneous ovulations. In contrast to the corpus luteum without cavity, the surface area of the corpus luteum with cavity remained constant during the study period, while at the same time the cavity decreased in size to a significant degree. In addition, breed differences in corpus luteum sizes were detected on day 34.

CONCLUSION

No cause was detected for the formation of cavities in corpora lutea and there was no link to the follicle from which the corpus luteum developed.

CLINICAL RELEVANCE

Both the changes in corpus luteum sizes over time and their breed-related differences could have an impact on insemination outcome.

Morphologic, Steroidogenic, and Transcriptomic Assessment of the Corpus Luteum in Holstein Cows after Spontaneous or Hormone-Induced Ovulation

There is evidence that replacing the gonadotropin-releasing hormone (GnRH) with porcine luteinizing hormone (pLH) to synchronize ovulation prior to artificial insemination (AI) increased pregnancy per AI in dairy cows without affecting blood progesterone (P₄) concentrations. Whether morphologic, steroidogenic, and transcriptomic differences exist among corpora lutea (CL) formed after ovulation induced by GnRH and pLH is unclear. Our main objective, therefore, was to compare CL characteristics between GnRH- and pLH-induced CL. In 24 non-lactating Holstein cows, ovulations were spontaneous (Spont-Ov) or induced with 100 µg GnRH, 25 mg pLH, or 1 mg estradiol benzoate (EB), with CL excised 12 d after ovulation. In pLH- versus GnRH-treated cows, the duration of elevated LH (above baseline) was prolonged (10 versus 6 h, respectively, p < 0.01), but CL dimensions, pixel intensity of CL images, proportions of steroidogenic and non-steroidogenic luteal cells, and mean plasma LH did not significantly differ. Post-ovulation mean plasma P₄ (ng/mL) did not differ among Spont-Ov (3.0) pLH (3.1) or GnRH (3.0) cows but were lower in EB cows (2.0). In vitro P₄ concentration was greater in luteal explants of pLH-treated cows than in all other groups (combined means, 16.0 vs. 12.3 µg/mL, p < 0.02). Relative abundance of mRNA for oxytocin receptor (OXTR) was 2-fold higher (p < 0.01) in CL of pLH vs. GnRH cows and highest in Spont-Ov CL. In summary, pLH-treated cows had a longer LH peak, and greatest luteal tissue concentrations and in vitro production of P₄. We inferred that increased P₄ concentrations at the ovarian-uterine level in pLH-treated cows could have promoted embryo development and increased pregnancy per AI.

Review: Current status of corpus luteum assessment by Doppler ultrasonography to diagnose non-pregnancy and select embryo recipients in cattle

A number of potentials uses of Doppler ultrasonography have been explored in the last decades, both as research tools in reproductive physiology investigations and for the reproductive management of farm animals. The objective of this review was to address some of the recent strategies developed in fixed-time reproductive programs and resynchronization of ovulation in cattle, based on the evaluation of corpus luteum function by color-Doppler ultrasound imaging. Recent studies in dairy and beef cattle pointed out to a high accuracy when Doppler ultrasonography is used to assess the functionality of the corpus luteum and identify non-pregnant females at 20-24 days after breeding. Therefore, super-early resynchronization programs starting in the second week after timed-artificial insemination or embryo transfer have been developed and are being implemented in commercial assisted reproduction programs; thus, anticipating conception with proven semen or genetically superior embryos. In addition, assessment of corpus luteum blood perfusion can be used for identifying high fertility embryo recipients in fixed-time embryo transfer programs.

The impact of the cavitary corpus luteum on the blood progesterone concentration and pregnancy rate of embryo recipient heifers

In cattle there are two types of the corpus luteum (CL): homogeneous (CL_hom) and cavitary (CL_cav). Although they are considered equal in their hormonal activity, the function of the CL_cav is questioned by many veterinarians. In consequence, females with the CL_cav are considered less valuable for assisted reproductive techniques such as embryo transfer (ET), where recipients with the CL_hom are preferred. The aim of our study was to compare the two types of CLs regarding morphological endpoints, serum progesterone (P4) concentrations and final pregnancy rate (PR) in recipient heifers after ET. The morphological type of the CL and the final PR after ET of 432 Holstein Friesian heifers were analyzed. Oestrus was synchronized with two i.m. inj. of 0.5 μg cloprostenol 14 days apart. The ET took place on the day 7 of the estrous cycle, only animals with visible oestrum were chosen for the procedure. Clinical and transrectal US examinations of ovaries were performed on the day of ET. The presence of the CL_hom or CL_cav was determined, and the CL diameter and cross-sectional area were measured. If present, measurements of the cavities were also taken. Only embryos recovered immediately prior to the ET at the morula or blastocyst stage were transferred to the randomly chosen recipient that underwent initial selection regardless of the CL morphology. Additionally, from randomly selected heifers (N = 53, CL_hom = 33; CL_cav = 20) blood samples for serum P4 concentration analysis were collected. Pregnancy was determined by transrectal palpation 2 months after ET. The medium-sized CL_cav was larger in diameter (P < 0.001) and cross-sectional area (P < 0.01) than the CL_hom (mean ± SD) - 23.29 ± 3.6 mm and 419.57 ± 135.01 mm² compared to 21.87 ± 3.57 mm and 384.73 ± 145.46 mm², respectively. The mean diameter and cross-sectional area of the cavity were 10.2 ± 4.36 mm and 97.59 ± 71.13 mm², respectively. The volume of both types of CLs was similar (P = 0.3). The mean serum P4 concentration was 8.84 ng/ml, higher (P < 0.0001) for females with the CL_cav (11.31 ng/ml) than for those with the CL_hom (7.15 ng/ml). The PR was 36.1%, higher (P < 0.05) for recipients with the CL_cav (47.7%) compared to the CL_hom (29.9%). The presence of a CL_cav in the recipient heifers did not negatively affect the potential of the CL to maintain pregnancy. On the contrary, the CL_cav may give the embryo better chances of surviving the time of pregnancy recognition and in consequence, may have a positive effect on PR in heifers.

Evaluation of ImageJ software in ultrasonic image analysis: Follicular and luteal morphological characteristics of cattle

This study was conducted to compare the effectiveness of two methodologies in evaluating B- and Doppler-mode ultrasonic images: analysis using ultrasonic software and utilizing a computer with ImageJ software. To determine if ImageJ software utilization is an efficacious alternative to ultrasonic software device- analysis, there were comparisons of values when using the two methods for morphological and vascular characteristics of follicular dynamics and luteal function in 18 crossbred cattle. From day 8 of an ovarian dynamics synchronization treatment regimen period until the time of ovulation (Day 10), B-mode and power-flow ultrasonic cineloops were obtained every 12 h to assess follicular diameter, wall area, and wall blood perfusion area. On Day 14 after ovulation, US cineloops of ovaries were obtained in B mode and power flow to evaluate various morphological and vascular characteristics of the corpus luteum (CL), including luteal diameter, luteal area, and CL blood perfusion area. Cineloops were evaluated and analyzed using ultrasonic software, and in a computer with ImageJ software. To evaluate consistency in results between the two methods, there was evaluation utilizing paired t-test, Pearson correlation coefficient, Bland-Altman plot, and Linear Regression Test procedures to calculate proportion of bias between values for measurements of variables evaluated. Results indicated none of the values for variables before and after ovulation differed (P > 0.05). It, therefore, was concluded that utilization of ImageJ software is an efficacious biomedical technique to analyze ultrasonic images of morphological and vascular characteristics before and after ovulation in cattle.

Ultrasound Characteristics of the Cavitary Corpus Luteum after Oestrus Synchronization in Heifers in Relation to the Results of Embryo Transfer

Simple Summary

In cattle there are physiologically two morphological forms of the corpus luteum: compact and with cavity. During ultrasound examination a fluid filled cavity is clearly visible. Routine ultrasound examination is performed—as a part of preselection—in embryo-recipient heifers/cows. Some vets eliminate recipients with cavitary corpus luteum from embryo transfer, considering them to be less suitable for an embryo to develop. In our research, we showed that the level of progesterone in the blood of recipients on Embryo Transfer day was higher in the case of cavitary corpus luteum than in the case of compact ones. Similarly, the pregnancy rate of recipients with a cavitary corpus luteum was higher. The presence of cavity inside the corpus luteum should not be a reason for the elimination of recipients from embryo transfer. Moreover, cavitary corpus luteum may be a valuable indicator of the recipient’s reproductive potential.

Abstract

The aim of the study was to conduct an ultrasound analysis of quantitative parameters of the corpus luteum (CL) in recipient heifers on days 6–8 after oestrus, and to compare reproduction potential of both types of CL in those females. Analyses were performed on 300 heifers, synchronized with two injections of cloprostenol. Clinical and ultrasound examinations of ovaries were performed and measurements of the CL were recorded. The blood samples were taken to determine progesterone level. Pregnancy examination was conducted after 6–8 weeks from the ET. Cavitary CL was found in 32.7% heifers In 48.0% of the cavitary CL, its luteal tissue area was reduced by 14.3% compared to the compact CL, while 16.3% of the CL had luteal tissue reduced by more than 33.8%. Progesterone level in blood serum was higher in heifers with the cavitary CL (p < 0.001). Pregnancy rate was higher for females with a cavitary CL (52%) than those with compact ones (33%, p < 0.05). The ultrasound assessment of luteal tissue should be included in the evaluation of the functional status of the CL in ET-recipient heifers. The cavitary CL presence may indicate a higher potential of the recipient in maintaining the pregnancy.

Early Prediction of Corpus Luteum Functionality Using an Imaging Software

The present study aimed to assess the applicability of luteal blood flow data acquired through the use of color Doppler ultrasonography and a post-processing analysis tool (ImageJ) for predicting pregnancy in buffaloes (Bubalus bubalis). The experiment was carried out on 59 multiparous Italian Mediterranean buffaloes that underwent synchronization of estrus and fixed-time artificial insemination (TAI). Corpus luteum features (size: CLS and blood flow: BFA) were taken from Day 5 to 10 after TAI and retrospectively measured with ImageJ. In the same period, blood samples were taken to assess progesterone (P₄) concentrations. Pregnancy diagnosis was carried out on Day 45 by ultrasound and confirmed on Day 70 post-TAI. Differences in CLS, BFA, and P₄ concentrations from Day 5 to 10 after TAI measured between groups were analyzed by ANOVA repeated measures as were differences within each day of measuring. Buffaloes that established a pregnancy (n = 29; 55%) had larger CLS (2.2 ± 0.1 vs. 1.9 ± 0.1 cm²; P < 0.01), higher BFA (0.6 ± 0.0 vs. 0.4 ± 0.0 cm²; P < 0.01), and higher P₄ blood level (1.8 ± 0.1 vs. 1.4 ± 0.1; P < 0.01) during Day 5–10 as compared to not-pregnant buffaloes (n = 22). Throughout the entire period, the first feature that changed between groups was P₄ blood concentration at Day 7 (1.7 ± 0.1 vs. 1.2 ± 0.1; P < 0.05) followed by BFA at Day 8 (0.6 ± 0.0 vs. 0.5 ± 0.0; P < 0.05), respectively, in pregnant and not-pregnant animals. The ROC analyses indicated that P₄ was able to predict pregnancy since Day 5 (P < 0.05) although a more reliable result could be obtained from Day 8 (P < 0.01). At Day 10, it was possible to set a cutoff value for every parameter taken into account. The logistic regression analysis showed that pregnancy was positively influenced by P₄ concentration (odds ratio 534.127; P < 0.01) and BFA (odds ratio 744.893; P < 0.01). In conclusion, the use of color Doppler ultrasonography, together with ImageJ, identified different patterns of BFA between pregnant and not-pregnant buffaloes starting from Day 8 post-TAI.

Vascular and morphological features of the corpus luteum 12 to 20 days after timed artificial insemination in dairy cattle

Our objective was to retrospectively compare pregnant versus nonpregnant cattle in terms of vascular and morphometric changes in corpora lutea between d 12 and 20 following timed artificial insemination (TAI). Crossbred (Gir × Holstein) lactating dairy cows (n = 136) and heifers (n = 111) were bred after synchronizing ovulations using an estradiol plus progesterone (P4)-based protocol. Corpus luteum (CL) characteristics (area, echotexture, blood flow) were recorded at 48-h intervals from d 12 to 20 following TAI using an ultrasound equipped with color Doppler. Blood samples were collected to determine CL function (plasma P4). Pregnancy diagnosis was performed at d 30. Quantitative assessment of colored pixels within the CL was performed using ImageJ software (National Institutes of Health, Bethesda, MD) and echotexture was quantified using custom software. Continuous variables such as luteal tissue area (LTA), CL blood flow (CLBF), adjusted CLBF (ratio LTA:CLBF), mean pixel value (MPV), pixel heterogeneity (HETER), and plasma P4 were analyzed retrospectively as repeated measures (d 12 to 20) in pregnant versus nonpregnant females using PROC MIXED (SAS Institute Inc., Cary, NC). Main effects were pregnancy status, day of cycle, and their interaction. Further analyses used only data from d 16, because this was the earliest time point of deviation between CLBF of pregnant and nonpregnant animals. We created quartiles for each variable and calculated the risk of pregnancy within quartile. Differences were determined using the chi-squared test. Plasma P4 was significantly higher in prospective pregnant versus nonpregnant cattle on d 18 and 20, whereas LTA differed only on d 20. On d 16, CLBF and adjusted CLBF diverged between pregnant and nonpregnant, followed by a progressive reduction in the latter until d 20. Mean pixel value was not affected by pregnancy status, but HETER was lower on d 20 in pregnant than in nonpregnant cattle. Likelihood of pregnancy increased from quartile (Q)1 (lowest values) to Q4 (highest) of CLBF (Q4 vs. Q1, odds ratio = 32.8, 95% confidence interval: 9.6 to 112.1) and adjusted CLBF [Q4 vs. Q1, odds ratio = 25.4, 95% confidence interval: 8.1 to 80.4), whereas a lower risk of pregnancy was observed only for animals within Q1 of plasma P4 [Q4 vs. Q1, odds ratio = 3.1, 95% confidence interval: 1.3 to 7.2). Day 16 quartiles of LTA, MPV, and HETER did not affect odds of pregnancy. In conclusion, we identified distinct CLBF patterns as early as 16 d after TAI and confirmed that CL function is lost by a reduction in blood flow, which precedes physical regression.

Corpus luteum dynamics after ovulation induction with or without previous exposure to progesterone in prepubertal Nellore heifers

The objectives of this study were 1) to monitor corpus luteum (CL) dynamics after two different protocols of ovulation induction in prepubertal Nellore heifers, and 2) to determine differences in luteal function. Fifty-seven heifers (weight 289.61 ± 32.28 kg, BCS 5.66 ± 0.65, age 17.47 ± 0.81 months) were divided into two groups: GP4+GnRH received a progesterone (P4) device of 3rd use for 10 days, followed by the administration of 0.02 mg buserelin acetate (GnRH) 48 h after removal of the device, and GGnRH received only GnRH. The CLs formed were monitored by ultrasonography every 2 days until their functional regression (decrease in the color Doppler signal and serum P4 concentration < 1 ng/mL), determining their diameter and area, numerical pixel value (NPV), pixel heterogeneity, and vascularization percentage. The peak systolic velocity, end diastolic velocity, resistivity index and pulsatility index (PI) of the ovarian artery and serum P4 concentration were also measured. A lifespan of the CL of more than 16 days was classified as normal-function and of less than 16 days as premature regression. The variables were compared between treatments, CL categories (normal-functional, prematurely regressed or non-functional), days of evaluation, and their interactions using the MIXED procedure of the SAS program (p ≤ 0.05). Three animals of each group (6/57 = 11%) did not respond to treatment, corresponding to an ovulation rate of 89%. There was a higher percentage of normal-function CLs in GP4+GnRH (81%) and a higher percentage of non-functional CLs in GGnRH (52%; P4 concentration < 1 ng/mL in all assessments). Normal-function CLs exhibited a greater area, vascularization percentage and P4 concentration than prematurely regressed and non-functional CLs. Lower diameter, area, NPV and P4 concentration were observed for non-functional CLs, but there was no difference in vascularization percentage compared to prematurely regressed CLs. Progesterone concentration was efficient in diagnosing CL function and was positively correlated with CL area (r = 0.62; p < 0.001) and vascularization percentage (r = 0.38; p < 0.001). Diameter and PI were important for the early diagnosis of non-functional and prematurely regressed CLs, respectively. In conclusion, luteal function differed for the first CL that develops after ovulation induction in prepubertal heifers. Ultrasonographic parameters (diameter, area, NPV, vascularization percentage, and PI) can be used to predict CL function.

Evaluation of endometrial echotexture and cervical cytology in cows during and after treatment of endometritis

OBJECTIVE

The aim of this study was to evaluate changes in the endometrium by using echotexture parameters during and after treatment of endometritis with intrauterine administration of an intrauterine antiseptic solution (Lotagen®, 3% metacresolsulphonic acid and formaldehyde) in cows which became pregnant after treatment.

MATERIAL AND METHODS

According to the severity of endometritis 21 cows were divided into three groups: E1 (slight, n = 7), E2 (moderate, n = 8), E3 (severe, n = 6). The control group (C, n = 11) consisted of cows without endometritis that did not receive an intrauterine medication. A software (Bs200 Pro®) was used to evaluate echotexture parameters Contrast (CON), Gradient (GR), Homogeneity (HOM), Mean Gray Level (MGL) of images taken during the examinations at hours (h) 0, 1 and 6 and days (d) 2, 3, 5 and 10.

RESULTS

At 0 h, GR was significantly lower in group E2 than in groups E1 and C (p < 0.05). There was an increase in GR values between 0 h and 10 d in group E2 and E3, but a decrease during the same time interval in group C (p < 0.05). In contrast, CON values of group E2 were lower (p < 0.05) at 0 h compared to other timepoints of examination and lower than in group C. HOM values were lower (p < 0.05) in groups E1, E2 and E3 than in group C on d 5 and d 10. HOM values were higher at 1 h compared to 6 h, d 2 and d 10 in group E3 (p < 0.05). By contrast to GR values, HOM values were higher in group C at 6 h and d 10 than they were in group E3. MGL values of group E2 were higher (p < 0.05) than in group C until d 10 and higher (p < 0.05) in group E3 than in group C at 6 h after treatment. In group E2 an increase of MGL values until d 2 was followed by a decrease (p < 0.05).

CONCLUSION

Echotexture parameters determined by the evaluation of sonographic B-mode images reflect changes in the endometrium and could be used for the evaluation of the recovery period after treatment of endometritis.

How ultrasound technologies have expanded and revolutionized research in reproduction in large animals

Gray-scale ultrasonic imaging (UI) was introduced in 1980 and initially was used to examine clinically the reproductive tract of mares. By 1983 in mares and 1984 in heifers/cows, UI had become a tool for basic research. In each species, transrectal gray-scale UI has been used extensively to characterize follicle dynamics and investigate the gonadotropic control and hormonal role of the follicles. However, the use of transrectal UI has also disclosed and characterized many other aspects of reproduction in each species, including (1) endometrial echotexture as a biological indicator of circulating estradiol concentrations, (2) relative location of the genital tubercle for fetal gender diagnosis by Days 50 to 60, and (3) timing of follicle evacuation during ovulation. Discoveries in mares include (1) embryo mobility wherein the spherical conceptus (6-16 mm) travels to all parts of the uterus on Days 11 to 15, (2) how one embryo of a twin set eliminates the other without self-inflicted damage, and (3) serration of the granulosum of the preovulatory follicle opposite to the future rupture site as an indicator of imminent ovulation. Studies with color-Doppler UI have shown that vascular perfusion of the endometrium follows the equine embryo back and forth between uterine horns and follows the expansion of the bovine allantochorion throughout each horn. In heifers, blood flow in the CL increases during the ascending portion of an individual pulse of PGF2α metabolite and then decreases. These examples highlight the power of UI in reproduction research. Without UI, it is likely that these and many other findings would still be unknown.

Bovine luteal blood flow: basic mechanism and clinical relevance

The introduction of transrectal colour Doppler sonography (CDS) has allowed the evaluation of luteal blood flow (LBF) in cows. Because appropriate angiogenesis plays a decisive role in the functioning of the corpus luteum (CL), studies on LBF may provide valuable information about the physiology and pathophysiology of the CL. Studies on cyclic cows have shown that progesterone concentrations in blood plasma can be more reliably predicted by LBF than by luteal size (LS), especially during the regression phase of the CL. In contrast with non-pregnant cows, a significant increase in LBF is seen in pregnant cows during the third week after insemination. However, because there are high interindividual variations in LBF between animals, LBF is not useful for the early diagnosis of pregnancy. Determination of LBF is more sensitive than LS for detecting the effects of acute systemic inflammation and exogenous hormones on the CL. Cows with low progesterone levels have smaller CL during the mid-luteal phase, but LBF related to LS did not differ between cows with low and high progesterone levels. In conclusion, LBF determined by CDS provides additional information about luteal function compared with LS and plasma progesterone concentrations, but its role concerning fertility in the cow is yet to be clarified.

Correlations between ultrasonographic characteristics of corpora lutea and systemic concentrations of progesterone during the discrete stages of corpora lutea lifespan and secretory activity in cyclic ewes

Associations between physical characteristics and functionality of corpora lutea (CL) have previously been reported in monovulatory species, albeit several studies in cattle and humans have refuted the existence of temporal relationships between CL size, echotexture and serum progesterone (P(4)) concentrations. The main objective of the present study was to examine whether or not there were correlations between ultrasonographic image attributes of CL and systemic concentrations of P(4) during the discrete stages of the luteal phase in two breeds of sheep differing in ovulation rates (non-prolific Western White Face [WWF] ewes and prolific Finn [F] sheep). Transrectal ovarian ultrasonography utilized a 7.5-MHz linear-array transducer connected to a portable scanner (Aloka SSD-500) and the images were analyzed using commercially available image analytical software (Image ProPlus(®)) validated for the present application in sheep. The correlations were assessed using the Pearson's Product Moment (PPM) analysis and also, to increase the accuracy of statistical tests, the analysis of covariance (ANCOVA), with the number of CL as a co-factor. In WWF ewes, serum concentrations of P(4) correlated significantly with the total luteal area (TLA) during the CL growth phase (days 3-6; day 0 = ovulation) and functional luteolysis (days 12-15), and with numerical pixel values (NPVs--pixel intensity) during luteolysis; the results obtained by using two different statistical methods were generally similar. In prolific F ewes, serum P(4) concentrations were directly correlated with TLA during CL growth (days 3-6; ANCOVA), functional luteolysis (days 13-14; PPM), and structural CL regression (days 11-14; PPM and ANCOVA), and with NPVs during functional luteolysis (PPM and ANCOVA). We concluded that systemic P(4) concentrations could only be accurately predicted from the changes in luteal area during CL growth and regression, and from NPVs during luteolysis, in both prolific and non-prolific ewes, but the changes in size and echotexture of the luteal glands at mid-cycle were not indicative of serum P(4) concentrations in sheep.

Pregnancy rates and corpus luteum-related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer

The objective was to investigate the influence of corpora lutea physical and functional characteristics on pregnancy rates in bovine recipients synchronized for fixed-time embryo transfer (FTET). Crossbred (Bos taurus taurus x Bos taurus indicus) nonlactating cows and heifers (n=259) were treated with the following protocol: 2mg estradiol benzoate (EB) plus an intravaginal progesterone device (CIDR 1.9g progesterone; Day 0); 400 IU equine chorionic gonadotropin (eCG; Day 5); prostaglandin F(2alpha) (PGF(2alpha)) and CIDR withdrawal (Day 8); and 1mg EB (Day 9). Ovarian ultrasonography and blood sample collections were performed on Day 17. Of the 259 cattle initially treated, 197 (76.1%) were suitable recipients; they received a single, fresh, quality grade 1 or 2 in vivo-derived (n=90) or in vitro-produced (n=87) embryo on Day 17. Pregnancy rates (23 d after embryo transfer) were higher for in vivo-derived embryos than for in vitro-produced embryos (58.8% vs. 31.0%, respectively; P<0.001). Mean (+/-SD) plasma progesterone (P(4)) concentration was higher in cattle that became pregnant than that in nonpregnant cattle (5.2+/-5.0 vs. 3.8+/-2.4 ng/mL; P=0.02). Mean pixel values (71.8+/-1.3 vs. 71.2+/-1.1) and pixel heterogeneity (14.8+/-0.3 vs. 14.5+/-0.5) were similar between pregnant and nonpregnant recipients (P>0.10). No significant relationship was detected between pregnancy outcome and plasma P(4), corpus luteum area, or corpus luteum echotexture. Embryo type, however, affected the odds of pregnancy. In conclusion, corpus luteum-related traits were poor predictors of pregnancy in recipients. The type of embryo, however, was a major factor affecting pregnancy outcome.

Evaluation of the ultrasound image attributes of developing ovarian follicles in the four follicular waves of the interovulatory interval in ewes

Computer-assisted quantitative echotextural analysis was applied to ultrasound images of antral follicles in the follicular waves of an interovulatory interval in sheep. The ewe has three or four waves per cycle. Seven healthy, cyclic Western White Face ewes (Ovis aris) underwent daily, transrectal, ovarian ultrasonography for an interovulatory interval. Follicles in the third wave of the ovulatory interval had a longer static phase than that of those in Waves 1 and 2 (P<0.05). The numeric pixel value for the wall of anovulatory follicles emerging in the third wave of the cycle was significantly higher than that for Waves 1 and 2 at the time of emergence (156.7+/-8.09, 101.6+/-3.72, and 116.5+/-13.93, respectively), and it decreased as follicles in Wave 3 reached maximum follicular diameter (P<0.05). The numeric pixel value of the antrum in the ovulatory follicles decreased as follicular diameter increased to > or =5mm in diameter (P<0.05). The pixel heterogeneity of the follicular antrum in Wave 1 increased from the end of the growth phase to the end of the regression phase for follicles in that wave (P<0.05). The total area for the wall and antrum of the follicles studied were correlated with follicular diameter in all follicular waves (r=0.938, P<0.01 and r=0.941, P<0.01 for the wall and antrum, respectively). Changes in image attributes of the follicular wall and antrum indicate potential morphologic and functional differences among antral follicles emerging at different stages of the interovulatory interval in cyclic ewes.

Level set segmentation of bovine corpora lutea in ex situ ovarian ultrasound images

BACKGROUND

The objective of this study was to investigate the viability of level set image segmentation methods for the detection of corpora lutea (corpus luteum, CL) boundaries in ultrasonographic ovarian images. It was hypothesized that bovine CL boundaries could be located within 1-2 mm by a level set image segmentation methodology.

METHODS

Level set methods embed a 2D contour in a 3D surface and evolve that surface over time according to an image-dependent speed function. A speed function suitable for segmentation of CL's in ovarian ultrasound images was developed. An initial contour was manually placed and contour evolution was allowed to proceed until the rate of change of the area was sufficiently small. The method was tested on ovarian ultrasonographic images (n = 8) obtained ex situ. A expert in ovarian ultrasound interpretation delineated CL boundaries manually to serve as a "ground truth". Accuracy of the level set segmentation algorithm was determined by comparing semi-automatically determined contours with ground truth contours using the mean absolute difference (MAD), root mean squared difference (RMSD), Hausdorff distance (HD), sensitivity, and specificity metrics.

RESULTS AND DISCUSSION

The mean MAD was 0.87 mm (sigma = 0.36 mm), RMSD was 1.1 mm (sigma = 0.47 mm), and HD was 3.4 mm (sigma = 2.0 mm) indicating that, on average, boundaries were accurate within 1-2 mm, however, deviations in excess of 3 mm from the ground truth were observed indicating under- or over-expansion of the contour. Mean sensitivity and specificity were 0.814 (sigma = 0.171) and 0.990 (sigma = 0.00786), respectively, indicating that CLs were consistently undersegmented but rarely did the contour interior include pixels that were judged by the human expert not to be part of the CL. It was observed that in localities where gradient magnitudes within the CL were strong due to high contrast speckle, contour expansion stopped too early.

CONCLUSION

The hypothesis that level set segmentation can be accurate to within 1-2 mm on average was supported, although there can be some greater deviation. The method was robust to boundary leakage as evidenced by the high specificity. It was concluded that the technique is promising and that a suitable data set of human ovarian images should be obtained to conduct further studies.

Examination of cyclic changes in bovine luteal echotexture using computer-assisted statistical pattern recognition techniques

B-mode sonography is a well-established diagnostic tool for determination of cycle stage in gynaecology. The aim of this study was to determine whether computer-assisted texture analysis of B- mode sonographic images of bovine luteal glands provides further information about the animal's plasma progesterone concentration and cycle stage. Four Simmenthal cows were examined during two consecutive estrous cycles with an ultrasound device equipped with a 7.5MHz microconvex probe. During each examination three B-mode images of the corpus luteum (CL) were digitized and analyzed off-line using a computer-assisted texture analysis program. Size, echogeneity, and echotexture of the CL were characterized by the following texture parameters: area of cross-sectional planes of the CL (A), mean gray level (MGL), correlation (CORR), run percentage (RPERC), and long-run emphasis (LREM). Plasma progesterone levels (P4) were also determined. All parameters showed characteristic changes during the estrous cycle (P<0.05). Variance component estimates for the effect of Day of estrous cycle on A, MGL, CORR, RPERC, and LREM were 56.6%, 64.6%, 77.6%, 89.9%, and 86.0%, respectively, and 20.6%, 24.5%, 7.2%, 0.0%, and 14.0% for the influence of the individual cow. The factor estrous cycle within cows was responsible for 22.8%, 10.9%, 15.2%, 10.1%, and 0.0% of the variability of A, MGL, CORR, RPERC and LREM values, respectively. Cyclic changes were similar in A and P4. In contrast to P4, which decreased already between Days -5 and -3 (Day 0=ovulation), A stayed at constant high values until Day -3. Mean MGL values were higher (P<0.05) on Days 7, 9, and 13 compared to Days 3 and -3. Mean CORR values were constantly high (P>0.05) during the first days after ovulation and decreased continuously (P<0.05) between Days 5 and 13. Thereafter, mean CORR values remained low (P<0.05) until the next ovulation, except on Day -3 (P<0.05). Mean RPERC rose between Days 1 and 9 from low to high values (P<0.0001) remained at these high values (P>0.05) between Days 9 and 15, and decreased (P<0.05) afterwards to baseline values on Day -1. Mean LREM inclined steeply (P<0.0001) from minimum to maximum between Days 1 and 5. From Days 7 to -3, mean LREM remained (P>0.05) at a constant level close below the maximum value, and decreased to baseline values on Day -1. The results of this study show that statistical pattern recognition techniques provide new information about the luteal glands, thus facilitating a more accurate differentiation between different cycle stages in cows.

Relationships between ultrasonographic image attributes, histomorphology and proliferating cell nuclear antigen expression of bovine antral follicles and corpora lutea ex situ

The aim of this study was to examine the relationships between quantitative ultrasonographic image characteristics, histological attributes and cell proliferating ability of bovine antral follicles and corpora lutea (CL) ex situ. Bovine ovaries (n = 30) from animals at various reproductive states (metoestrus-early dioestrus, n = 8; mid-dioestrus, n = 12; oestrous phase of peripubertal heifers, n = 6; and pregnancy, n = 4) were collected at the slaughterhouse. High-resolution ultrasonographic images of the ovaries were obtained in the water bath, digitized and subjected to computerized image analyses. The analyses utilized line and spot techniques designed to determine pixel values of the follicular wall (the largest follicles >2 mm in diameter in each ovary) and CL, respectively. Individual ovarian structures were dissected and processed for histology and immunohistochemical detection of proliferating cell nuclear antigen (PCNA). The mean follicular diameter was negatively correlated with total cell density (r = -0.45, p < 0.05), granulosa layer thickness (r = -0.67, p < 0.001) and the percentage of PCNA-positive cells (r = -0.57, p < 0.001). Numerical pixel values and heterogeneity of the follicular wall were positively correlated with total cell density (r = 0.42, p < 0.05 and r = 0.62, p < 0.05; respectively), granulosa layer thickness (both r = 0.39, p < 0.05), and the percentage of PCNA-positive cells (r = 0.54, p < 0.01 and r = 0.69, p < 0.001, respectively). Estimates of cell density and proliferating cell index were not correlated with the ultrasonographic image attributes of CL. We conclude that follicular size and echotextural variables, as determined by computer-assisted image analysis of ovaries ex situ, are reliable markers of the histophysiological properties of bovine antral follicles, but the ultrasonographic characteristics are not indicative of cell density and proliferation in the bovine CL.

Computer assisted image analyses of corpora lutea in relation to peripheral concentrations of progesterone: A comparison between breeds of sheep with different ovulation rates

Transrectal ovarian ultrasonography is a non-invasive technique that permits the real-time serial visualization of ovarian structures. Previous studies have reported correlations between serum progesterone concentrations and physical characteristics of the corpus luteum (CL) in different species. The aim of the present study was to investigate whether or not there were correlations between ultrasound image attributes of the CL and changing progesterone concentrations over time, in prolific and non-prolific ewes. Ultrasonographic images of CL were taken, once daily, from 12 Western White Face ewes and 7 Finn ewes for the duration of one luteal phase. Blood samples were collected daily prior to each scanning session and assayed to determine mean serum concentrations of progesterone. Analysis of ultrasound images was performed using a series of custom-developed computer algorithms optimized for ultrasonography on a computer graphics workstation. Both total luteal area and mean pixel values were correlated with the pattern of serum concentrations of progesterone from days 3 to 15 after ovulation in Western White Face ewes and from days 3 to 14 in Finn ewes. There was no significant correlation between progesterone concentrations and spot pixel heterogeneity for either Western White Face ewes or Finn ewes. We concluded that pixel heterogeneity is a poor indicator of progesterone secretory ability of the CL when compared to mean pixel values. However, luteal area and mean spot pixel values are better but not strong indicators of the functional status of the CL in cyclic ewes.

Ultrasound image attributes of human ovarian dominant follicles during natural and oral contraceptive cycles

BACKGROUND

Computer-assisted analyses were used to examine ultrasound image attributes of human dominant ovarian follicles that developed during natural and oral contraceptive (OC) cycles. We hypothesized that image attributes of natural cycle follicles would quantitatively differ from those in OC cycles and that OC cycle follicles would possess image attributes indicative of atresia.

METHODS

Dominant ovarian follicles of 18 clinically normal women were compared using transvaginal ultrasonography for the 7 days before ovulation during a natural cycle (n = 9) or the 7 days before peak estradiol in women using OC (n = 11). Follicles were analyzed using region and line techniques designed to compare the image attributes numerical pixel value (NPV), pixel heterogeneity (PH) and area under the curve (AUC).

RESULTS

NPV was higher in OC cycle follicles with region analysis and tended to be higher with line analysis (p = 0.005 and p = 0.06, respectively). No differences were observed in two other image attributes (AUC and PH), measured with either technique, between natural and OC cycle follicles.

CONCLUSION

The increased NPV value of OC cycle follicles and lack of differences in PH and AUC values between natural cycle and OC cycle follicles did not support the hypothesis that OC cycle follicles would show ultrasonographically detectable signs of atresia. Image attributes observed in OC cycle follicles were not clearly indicative of atresia nor were they large enough to preclude preovulatory physiologic status in OC cycle follicles.

Intraovarian blood flow measured with color doppler ultrasonography inversely correlates with vascular density in the human corpus luteum of the menstrual cycle

OBJECTIVE

To evaluate the morphologic characteristics underlying the ultrasonographic appearance and blood flow dynamics in the human corpus luteum (CL) of the menstrual cycle.

DESIGN

Cross-sectional study.

SETTING

Umeå University Hospital, Umeå, Sweden.

PATIENT(S)

Twenty-six otherwise healthy women with proven fertility and a history of regular menstrual cycles, scheduled for elective hysterectomy or tubal sterilization.

INTERVENTION(S)

An ovulatory LH rise in urine was established and the CL age was determined according to the day after the LH rise. Before surgery, a standardized ultrasonographic examination of the CL, including B-mode and color Doppler ultrasonography measurements, was performed. Upon commencing the minilaparotomy, the CL was excised and measured using a digital slide-caliper. The volume density (percentage of CL volume occupied by blood vessels) of factor VIII-related antigen immunostained endothelial cells was determined.

MAIN OUTCOME MEASURE(S)

Pulsatility index obtained from intraovarian blood vessels supplying the CL and volume density of blood vessels in CL tissue. The CL maximal and minimal outer and inner dimensions were measured in vivo by ultrasonography and ex vivo by a digital slide caliper.

RESULT(S)

A statistically significant decrease of blood vessel density and an increased resistance to blood flow, as indicated by pulsatility index, was established during the course of corpus luteum development. An inverse correlation between pulsatility index and volume density of blood vessels was found. A high degree of agreement between ultrasonographic and anatomic measurements of surgically removed CL was found.

CONCLUSION(S)

Transvaginal ultrasonography in combination with intraovarian color Doppler flow measurements is a simple and reliable method to evaluate the size and vascularization of the human CL.

Promise of new imaging technologies for assessing ovarian function

Advancements in imaging technologies over the last two decades have ushered a quiet revolution in research approaches to the study of ovarian structure and function. The most significant changes in our understanding of the ovary have resulted from the use of ultrasonography which has enabled sequential analyses in live animals. Computer-assisted image analysis and mathematical modeling of the dynamic changes within the ovary has permitted exciting new avenues of research with readily quantifiable endpoints. Spectral, color-flow and power Doppler imaging now facilitate physiologic interpretations of vascular dynamics over time. Similarly, magnetic resonance imaging (MRI) is emerging as a research tool in ovarian imaging. New technologies, such as three-dimensional ultrasonography and MRI, ultrasound-based biomicroscopy and synchrotron-based techniques each have the potential to enhance our real-time picture of ovarian function to the near-cellular level. Collectively, information available in ultrasonography, MRI, computer-assisted image analysis and mathematical modeling heralds a new era in our understanding of the basic processes of female and male reproduction.

Luteogenesis in cyclic ewes: echotextural, histological, and functional correlates

To date, it has not been possible to detect corpus luteum (CL) by ultrasonography, immediately following ovulation, in the ewe. Early CL detection is essential to be able to relate luteal outcome to the developmental pattern of the ovulated follicle and to confirm ovulation. Image analysis of the CL may be useful in providing a noninvasive picture of CL differentiation and function. The present study was designed to use high-resolution ultrasonography to monitor and to correlate the echotextural, histological, and functional attributes of the developing ovine CL from Days 1 to 3 after ovulation. Ten ewes underwent twice-daily transrectal ultrasonography and blood sampling from the day of synchronized estrus. Ewes were ovariectomized at 12-24, 36-48, and 60-72 h after ovulation. Ovaries collected were scanned in a water bath before processing for histology. Ultrasonographic images of CL were analyzed for echotexture. Histological sections were analyzed for the percentage area of the CL occupied by blood clot or luteal tissue. Serum samples were analyzed for progesterone concentration. Numerical pixel value, heterogeneity, and percentage of the CL occupied by blood clot declined (P<0.05) from 12-24 to 60-72 h after ovulation. Luteal area and serum progesterone concentration increased (P<0.05) from 12-24 to 60-72 h. The results indicated that it was possible to visualize developing CL as early as 12-24 h after ovulation in the ewe. Echotexture of the CL was closely associated with its morphological and functional characteristics; image analysis holds promise for noninvasive monitoring of CL differentiation and growth.

Magnetic resonance image attributes of the bovine corpus luteum during development and regression

To determine whether magnetic resonance (MR) image attributes of the corpus luteum (CL) reflect its physiologic status at different phases of the bovine ovarian cycle, we analyzed the numerical pixel values (NPVs), relaxation rates, proton densities (PDs), and apparent diffusion coefficients (ADCs) from T(1)-, T(2)-, and diffusion-weighted in vitro images and maps of the CL acquired at defined phases of luteal function. Ovaries were removed and serum samples taken on days 3, 6, and 10, or >/=17 (day 0 = ovulation), representing metestrus (n = 10), early diestrus (n = 7), mid-diestrus (n = 9), and proestrus (n = 7), respectively. Regions of interest (ROIs) in each quadrant of the CL (which occupied at least 20% of the quadrant) were selected for analysis. Three MR image slices were analyzed: the slice with the greatest cross-sectional area of the CL, and the slices acquired immediately before and after that slice. The mean NPVs of the CL in T(1)-weighted images increased at each phase from metestrus (1,104 +/- 40 msec) to early diestrus (1,119 +/- 77 msec), to late diestrus (1,206 +/- 43 msec) and proestrus (1446 +/- 80 msec; P < 0.001). The mean NPVs in T(1)-weighted images were higher in regressing CL (proestrous) than in any other phase (P < 0.002). Grayscale heterogeneity of CL in T(1)-weighted images tended to increase during regression (P < 0.07). Regressing CL (proestrus) exhibited higher T(1)-weighted mean NPVs (P < 0.01) and tended to have greater heterogeneity (P < 0.06) than growing (metestrus) and mature (diestrus) CL, even though similar progesterone concentrations were observed. The increased brightness and heterogeneity of regressing CL in T(1)-weighted images appeared to be correlated with increased connective tissue and triglyceride content and decreased vascularity. It is anticipated that diagnostic markers for luteal viability and atresia in the in vitro bovine model will be applied to in vivo studies in women.

Ultrasound image characteristics of ovarian follicles in relation to oocyte competence and follicular status in cattle

Assessment of the quality of the female gamete has become paramount for in vitro procedures. There is a need to identify reliable indicators of oocyte competence and develop a simple, non-invasive method to assess competence. The aim of this study was to investigate the relationships among ultrasonographic attributes of a follicle, its stage of development and the competence of the oocyte that it contains. We tested the hypotheses that follicular echotexture characteristics are related to: (1) the phase of development of the follicle, (2) the presence of the corpus luteum (CL) and/or the dominant follicle in the ovary, and (3) developmental competence of cumulus oocyte complexes (COC) from the same ovary. Crossbred beef cows (n=143), age 4-14 years, were given a luteolytic dose of dinoprost to cause ovulation. Ultrasound-guided ablation of all follicles > or = 4mm was done 8 days later to induce new follicular wave emergence during a luteal phase. Ultrasonographic images of dominant follicles and the three largest subordinate follicles (n=402 follicles; 84 cows) were acquired on Days 2, 3, 5 or 7 of the follicular wave (Day 0: wave emergence), i.e. growing, early-static, late static, and regressing phases of subordinate follicle development, respectively. From a subset of these animals (n=33), ovaries were collected within 30 min of slaughter and COC from subordinate follicles > or = 3mm underwent in vitro maturation, fertilization and culture to the blastocyst stage.Image analysis revealed differences in echotexture between dominant and subordinate follicles among Days 2-7 of the follicular wave. Images of dominant and subordinate follicles at Day 7 of the wave displayed consistently lower grey-scale values (P<0.05) in the peripheral antrum, follicular wall and perifollicular stroma than all other days. Follicle images displayed a consistent pattern of variation in echotexture among follicular phases. Data did not support the hypothesis of a local effect of the CL or dominant follicle on follicular echotexture. Echotexture values of the perifollicular stroma were lower in ovaries that did not produce embryos compared to ovaries that produced embryos. Our results showed that the changes in follicular image attributes are consistent with changes in follicular status. The sensitivity of the technique is not yet sufficient for use in a diagnostic setting, but results provide rationale for further development of image analysis as a tool for evaluating oocyte competence in situ.

Evaluating recipient and embryo factors that affect pregnancy rates of embryo transfer in beef cattle

The objectives of this experiment were to determine the effects of corpus luteum characteristics, progesterone concentration, donor-recipient synchrony, embryo quality, type, and developmental stage on pregnancy rates after embryo transfer. We synchronized 763 potential recipients for estrus using one of two synchronization protocols: two doses of PGF2alpha (25 mg i.m.) given 11 d apart (Location 1); and, a single norgestomet implant for 7 d with one dose of PGF2alpha (25 mg i.m.) 24 h before implant removal (Location 2). At embryo transfer, ovaries were examined by rectal palpation and ultrasonography. Of the 526 recipients presented for embryo transfer, 122 received a fresh embryo and 326 received a frozen embryo. Pregnancy rates were greater (P < 0.05) with fresh embryos (83%) than frozen-thawed embryos (69%). Pregnancy rates were not affected by embryo grade, embryo stage, donor-recipient synchrony, or the palpated integrity of the CL. Corpus luteum diameter and luteal tissue volume increased as days post-estrus for the recipients increased. However, pregnancy rates did not differ among recipients receiving embryos 6.5 to 8.5 days after estrus (P > 0.1). There was a significant, positive simple correlation between CL diameter or luteal tissue volume and plasma progesterone concentration (r = 0.15, P < 0.01 and r = 0.18, P < 0.01, respectively). There were no significant differences in mean CL diameter, luteal volume or plasma progesterone concentration among recipients that did or did not become pregnant after embryo transfer. We conclude that suitability of a potential embryo transfer recipient is determined by observed estrus and a palpable corpus luteum, regardless of size or quality.

Transvaginal, ultrasound-guided biopsy of the corpus luteum in cattle

An ultrasound-guided transvaginal technique for corpus luteum biopsy was developed and tested in cattle. The biopsy needle set consisted of an inner needle (o.d. 1 mm) with a 20-mm long specimen notch, an outer cannula (o.d. 1.2 mm) with a cutting edge, and an automated spring-loaded handle with trigger. The biopsy needle set was inserted into the channel guide of the handle of a convex-array transvaginal ultrasound probe. The transducer was positioned in the vaginal fornix, and the ovary was manipulated transrectally against the vaginal wall and transducer face. During monitoring on the ultrasound screen, the inner needle was pushed through the vaginal wall into the corpus luteum, and the cutting cannula was fired, cutting and trapping luteal tissue in the specimen notch. Three luteal biopsies at each of Hours 0 and 4 were taken 10 d after ovulation in 6 heifers; 6 other heifers served as controls. A biopsy core was obtained in 36 of 39 attempts (92%). The tissue specimens seemed normal based on gross evaluation. The effect of biopsy on luteal function was assessed by daily ultrasound monitoring of luteal area, by assay of progesterone concentrations in blood samples obtained daily, and by the length of the interval from biopsy to ovulation. No significant differences were found for post-biopsy function for any of the 3 end points. The results indicated repeated transvaginal, ultrasound-guided biopsy of the corpus luteum in cattle is a practical procedure and may be useful for experimental and diagnostic purposes.

Características morfológicas e funcionais do corpo lúteo durante o ciclo estral em vacas da raça Gir

Estudaram-se o desenvolvimento, a função e a regressão luteal em vacas da raça Gir. As características morfológicas do corpo lúteo foram avaliadas ao longo de um ciclo estral completo (n=15), utilizando-se um aparelho portátil de ultra-som. A atividade luteal foi monitorada pela concentração plasmática de progesterona. O corpo lúteo foi inicialmente identificado aos 3,28±0,19 dias após a ovulação. Observou-se efeito significativo do dia do ciclo sobre a área da seção transversal do corpo lúteo (P<0,0001), do tecido luteal (P<0,0001) e sobre a concentração de progesterona (P<0,0001). A área média do corpo lúteo entre os dias 7 e 16 do ciclo foi de 3,21±0,05cm², das cavidades luteais 0,42±0,04cm², do tecido luteal 3,06±0,05cm², e a concentração média de progesterona foi de 4,61±0,17ng/ml. A taxa de crescimento luteal entre a primeira detecção e o dia 7 do ciclo foi de 0,42<FONT FACE="Symbol">5</FONT>0,05cm²/dia, e a taxa de regressão entre os dias 16 e 21 foi de -0,36±0,04cm²/dia. As características morfológicas e funcionais do corpo lúteo de vacas da raça Gir são semelhantes àquelas observadas em outras raças bovinas.

Remote assessment of ovarian response and follicular status using visual analysis of ultrasound images

Computer assisted evaluation of ultrasonographic image attributes indicative of viability and atresia of ovarian follicles has the potential to become an integral part of ovarian superstimulation protocols. However, in many cases, animal handling facilities, laboratories providing image analysis services and the individual making clinical decisions are geographically separated. The feasibility of remote assessment of follicular status and ovarian response to superstimulation is demonstrated using internet and video conferencing techniques. A cohort of heifers (n = 6) was subjected to ovarian superstimulation. Ultrasound images of the ovarian responses were digitally acquired and transmitted to a distant laboratory for quantitative assessment. Images from follicles which ovulated in response to luteolysis and GnRH treatments were visually and quantitatively different from follicles committed to atresia. Two types of atresia were observed; images of non-ovulatory follicles were characterized as being reflective of the potential to develop into either follicular or luteal cysts. It is probable that the response of individual follicles to the pharmacologic agents used for ovarian superstimulation and ovulation induction may be as important as the total number of follicles recruited. Thus, assessment of the progress and fates of individual follicles may be used to tailor ovarian stimulation to individual donor animals to increase the probability of successful ovarian stimulation and embryo production. The use of the internet for data transfer, image analysis and clinical evaluation places the prospects of providing useful information within the grasp of practitioners who wish to have access to the biological information, but do not wish to invest in the equipment required to make quantitative assessments of visual data.