Time-Course of the Uterine Response to Estradiol: DISCUSSION(4)


However, in the present study, microvascular volume density increased nearly 2fold from 0 to 24 h. Thus, our data indicate that vasodilation probably accounts for a significant portion of the uterine microvascular response to E2, which is consistent with its well-known role as a powerful stimulator of uterine blood flow. It is highly unlikely, however, that the uterine microvascular response was due solely to vasodilation, because many of the microvessels that we quantified were capillaries, which do not possess vascular smooth muscle and are therefore incapable of dilation. The dramatic increase in total microvascular volume, therefore, most likely involved both microvascular vasodilation and growth. birth control yasmin

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Time-Course of the Uterine Response to Estradiol: DISCUSSION(3)

In the mouse myometrium, however, nuclear incorporation of [3H]thymidine increased only slightly, and numbers of cells did not change, even though myo-metrial volume increased dramatically. Thus, in OVX, E2-treated mice, the response of the myometrium was due almost entirely to increased cell size, whereas in sheep, both increased cell proliferation and cell size contributed to myometrial growth. cialis professional

In the present study, cell number (DNA content) of the uterus did not change from 24 to 72 h after E2 treatment, even though the rate of cell proliferation remained high in all of the uterine tissue compartments. This observation suggests that cell death must have increased dramatically after 24 h and is consistent with a dramatic increase in cell death observed at 16-40 h after E2 treatment in OVX mice. In mice, however, the onset of cell death was accompanied by a decrease in uterine weight and tissue volume, whereas in sheep we did not observe a decrease in uterine weight nor in the volume of the uterine tissue compartments.

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Time-Course of the Uterine Response to Estradiol: DISCUSSION(2)


In the present study, the uterine growth response was due primarily to tissue growth (hyperplasia and hypertrophy) rather than to a change in the ratio of tissue dry weight:fresh weight. In addition, tissue growth was due approximately equally to hyperplasia and hypertrophy during the initial 24 h after E2 treatment. The initial uterine growth response differed from that observed for immature or ovariectomized rats, in which uterine growth at 6-12 h after E2 is due primarily to a change in the tissue dry weight:fresh weight ratio. However, by 24 h after E2 treatment, the growth of the rodent uterus was reflected by uterine hyperplasia and hypertrophy, which is similar to our observations for the sheep uterus. In addition, the endometrium and myometrium remained a constant proportion of the uterus in OVX, E2-treated mice, similar to our observations in the present study. buy cipro

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Time-Course of the Uterine Response to Estradiol: DISCUSSION(1)

Although uterine responses to E2 have been investigated in OVX rodents, rabbits, primates, and ruminants, we are not aware of any study in which uterine growth, cell proliferation, and microvascular development have been evaluated in the same animals. In addition, because of the importance of steroid-mediated uterine responses during pregnancy and also in pathological conditions such as endometrial hyperplasia or abnormal uterine bleeding, we and others have recognized the importance of using animal models to investigate these responses. The results of the present study will provide a foundation for future investigations of the mechanisms responsible for the profound effects of E2 on uterine growth in OVX sheep. buy flovent inhaler

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Time-Course of the Uterine Response to Estradiol: RESULTS(4)


By 24 h, however, moderate (glandular epithelium) to extensive (luminal epithelium and stroma) BrdU incorporation was observed in the endometrium; BrdU labeling in the myometrium, however, was still low (Table 4). At 48 h and 72 h, a relatively large proportion of the cells exhibited nuclear incorporation of BrdU, indicating a relatively high rate of cell proliferation, in all of the uterine compartments including the myometrium (Table 4). As observed in our previous studies, BrdU labeling was exclusively nuclear, and endometrial labeling occurred mostly in the luminal compartments (data not shown). birth control yasmin

Endometrial microvascular volume increased dramatically from 0 to 24 h after E2 treatment; histologically, this was manifest as a dramatic increase in the density of microvessels (Fig. 1). Across all of the endometrial tissue compartments, volume density of the microvasculature increased linearly (p < 0.01) between 0 h and 24 h (4.7 vs. 8.4%; SE = 1.2%) and then remained constant (Fig. 2). In addition, across all times the volume density of microvessels was similar for caruncular and intercaruncular tissues (6.8 vs. 6.1%; SE = 0.4%) but was greater (p < 0.01) for luminal than for deep regions (6.9 vs. 5.8%; SE = 0.4%).

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Time-Course of the Uterine Response to Estradiol: RESULTS(3)

The further dramatic increase in uterine size that occurred between 24 h and 48 h (Table 1), however, was due primarily to increased cell size, since both the RNA:DNA and protein: DNA ratios increased (p < 0.01), whereas uterine DNA content remained constant (Table 3). In addition, the cellular hypertrophy was reflected by cellular morphology, with an increase in nuclear and cellular volume throughout all of the uterine tissue compartments by 24-48 h after E2 treatment (data not shown). buy cheap antibiotics

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Time-Course of the Uterine Response to Estradiol: RESULTS(2)


The cross-sectional areas of the uterine lumen, endometrium, and myometrium all increased (p < 0.01) from 0 to 72 h (Table 2). In addition, across all groups the crosssectional area of the endometrium was less (p < 0.01) than that of the myometrium (Table 2). The endometrium and myometrium remained constant proportions (p > 0.10) of the total uterine (endometrial + myometrial) tissue area from 0 to 72 after E2 treatment, averaging 26.2 ± 1% and 73.8 ± 1%, respectively (Table 2). Thus, both the endometrium and myometrium also remained constant proportions of uterine volume. canadian health&care mall

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