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Endometriosis is a chronic, treatable disease of the female reproductive tract associated with infertility and pelvic pain in women of reproductive age. The endometrium, a layer of epithelial tissue that grows and sheds during the menstrual cycle, normally makes up the interior lining of the uterus. In individuals with endometriosis, endometrial tissue is also found ectopically (outside the uterine cavity) .The mechanism by which endometrial tissue successfully implants outside the uterine cavity is thought to be dependent on signaling molecules that promote the formation of blood vessels locally. One of these signaling molecules is vascular endothelial growth factor (VEGF) , a protein that is normally synthesized and secreted by various tissues in response to reduced oxygen levels. Because VEGF is thought to be implicated in ectopic endometrial tissue growth, researchers hypothesize that the abdominal and pelvic structures of women with endometriosis would contain higher levels of VEGF compared to women without endometriosis.In an experiment, women ages 25-40 were divided into groups based on endometriosis disease status. Individuals on any type of medication were excluded from the study. Using minimally invasive surgery, samples of peritoneal fluid were taken from healthy subjects (n = 19) and from subjects diagnosed with endometriosis (n = 30) . An enzyme-linked immunosorbent assay (ELISA) was used to characterize the concentration of VEGF protein present within these samples.In a separate procedure that took place five days after peritoneal fluid collection, uterine endometrial samples were obtained from all subjects and visualized under a microscope to determine the menstrual cycle phase of each participant. Figure 1 shows the level of VEGF in the abdominal fluid categorized by disease status and menstrual cycle phase.
Figure 1 VEGF concentration in sampled peritoneal fluid (Note: * = p < 0.05; Proliferative phase = stage immediately preceding ovulation; Secretory phase = stage immediately following ovulation)
-Progesterone concentration is generally lowest in the proliferative phase and highest in the secretory phase of the menstrual cycle. The investigators conclude that VEGF concentrations within peritoneal fluid may be inversely correlated with serum levels of progesterone. Do the data support this conclusion?

Question

Passage
Endometriosis is a chronic, treatable disease of the female reproductive tract associated with infertility and pelvic pain in women of reproductive age. The endometrium, a layer of epithelial tissue that grows and sheds during the menstrual cycle, normally makes up the interior lining of the uterus. In individuals with endometriosis, endometrial tissue is also found ectopically (outside the uterine cavity) .The mechanism by which endometrial tissue successfully implants outside the uterine cavity is thought to be dependent on signaling molecules that promote the formation of blood vessels locally. One of these signaling molecules is vascular endothelial growth factor (VEGF) , a protein that is normally synthesized and secreted by various tissues in response to reduced oxygen levels. Because VEGF is thought to be implicated in ectopic endometrial tissue growth, researchers hypothesize that the abdominal and pelvic structures of women with endometriosis would contain higher levels of VEGF compared to women without endometriosis.In an experiment, women ages 25-40 were divided into groups based on endometriosis disease status. Individuals on any type of medication were excluded from the study. Using minimally invasive surgery, samples of peritoneal fluid were taken from healthy subjects (n = 19) and from subjects diagnosed with endometriosis (n = 30) . An enzyme-linked immunosorbent assay (ELISA) was used to characterize the concentration of VEGF protein present within these samples.In a separate procedure that took place five days after peritoneal fluid collection, uterine endometrial samples were obtained from all subjects and visualized under a microscope to determine the menstrual cycle phase of each participant. Figure 1 shows the level of VEGF in the abdominal fluid categorized by disease status and menstrual cycle phase.

Figure 1 VEGF concentration in sampled peritoneal fluid (Note: * = p < 0.05; Proliferative phase = stage immediately preceding ovulation; Secretory phase = stage immediately following ovulation)
-Progesterone concentration is generally lowest in the proliferative phase and highest in the secretory phase of the menstrual cycle. The investigators conclude that VEGF concentrations within peritoneal fluid may be inversely correlated with serum levels of progesterone. Do the data support this conclusion?

Quizplus · Accepted Answer

11ecba2d_1001_546f_a3bf_71a98ad959f4_MD0008_00 The rise and fall of the female sex hormones estrogen and progesterone are an important driver of the menstrual cycle, the cyclical changes in ovarian and uterine function that promote pregnancy. For example, serum progesterone levels rise substantially following ovulation. This progesterone is secreted by the corpus luteum (the portion of the ovarian follicle remaining in the ovary following ovulation) and maintains the uterine lining, which at this point in the cycle has thickened in preparation for the implantation of an embryo. If pregnancy does not occur, the corpus luteum degenerates and progesterone levels fall as a new cycle begins. An inverse correlation between two variables is observed when the value of one variable decreases as the value of the other increases. In both the healthy participants and those with endometriosis, VEGF concentrations were highest during the pre-ovulatory proliferative phase (when progesterone concentration is lowest). Likewise, VEGF concentrations were lowest during the post-ovulatory secretory phase (when progesterone concentration is highest). These findings support the conclusion that peritoneal VEGF concentration and serum level of progesterone are inversely correlated. (Choice A) According to Figure 1, VEGF concentration is lowest during the secretory phase of the menstrual cycle in both healthy individuals and patients with endometriosis. Because serum progesterone levels are highest in the secretory phase, this information supports the conclusion that there may be an inverse relationship between peritoneal VEGF concentration and serum progesterone levels. (Choice B) No information regarding the serum level of progesterone in healthy individuals versus patients with endometriosis was collected during this experiment. (Choice D) Peritoneal VEGF concentration was elevated in women with endometriosis only during the proliferative phase of the menstrual cycle. If peritoneal VEGF concentration was shown to be elevated in patients with endometriosis in general (ie, regardless of the menstrual cycle phase and consequently, regardless of serum progesterone levels), this would suggest that there is no relationship between VEGF and progesterone. Educational objective: Changes in the serum levels of estrogen and progesterone cause the physiological changes associated with the menstrual cycle, the female reproductive cycle that repeats every 24-36 days.