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Search for other papers by G. J. MARCUS in
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SUMMARY
In the normal non-pregnant guinea-pig uterus, proliferation of the surface epithelium occurred principally on day 3 after oestrus (vaginal opening). Intense mitotic activity occurred on the following day in the lower regions of the glands. Mitotic activity was pronounced in the endometrial stroma on the succeeding 2 days.
In the ovariectomized guinea-pig, oestrogen stimulated cell devision only in the surface and superficial glandular epithelia, but conditioned the endometrium to respond to progesterone so that at least 2 successive days of progesterone treatment after oestrogen priming elicited both intense glandular proliferation and extensive stromal cell division, while progesterone alone induced uterine closure.
The proliferative responses of the guinea-pig endometrium thus resembled the responses of the rabbit endometrium rather than the rat or mouse endometrial reaction to hormonal stimulation.
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Search for other papers by D. C. Wathes in
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ABSTRACT
Oxytocin-binding sites in the endometrium and myometrium of the non-pregnant ewe were characterized. [3H]Oxytocin bound to a single site in both tissues with high affinity; dissociation constants were determined to be 1·96 nmol/l in endometrium and 2·12 nmol/l in myometrium. Oxytocin binding was enhanced by divalent cations with a similar order of potency in both tissues: Co2+> Mn2+> Ni2+> Mg2+ > Zn2+> Ca2+. The endometrial and myometrial binding sites showed the same specificity for oxytocin analogues and related peptides, having high affinity for oxytocin, [Arg8]-vasopressin, [Lys8]-vasopressin, and the oxytocin-specific agonists [Gly7]-oxytocin and [Thr4,Gly7]-oxytocin. The results suggest that oxytocin receptors present in the endometrium and myometrium of the ewe are similar both to each other and to classical oxytocin receptors.
Journal of Endocrinology (1989) 123, 11–18
Search for other papers by D. Ghosh in
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Search for other papers by J. Sengupta in
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ABSTRACT
Acid phosphatase activity in both total and subcellular fractions of endometrium of rhesus monkey on day 5 of gestation was significantly (P <0·01) lower than levels found in tissues collected from normally menstruating monkeys on day 5 after ovulation. This endometrial response to preimplantation embryo may be related to the menstrual withdrawal in a fertile cycle.
Search for other papers by M. T. LUU THI in
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Search for other papers by E. E. BAULIEU in
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Search for other papers by E. MILGROM in
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SUMMARY
The characteristics of endometrial and myometrial progesterone receptor of guinea-pig were compared. Affinity for progesterone, hormone specificity, sedimentation properties (in oestrogen-primed animals), inhibition of binding by p-hydroxymercuribenzoate were found to be identical in both tissues. Differences were, however, observed in the hormonal control of the concentration of receptor. In all the situations studied, the concentration of receptors was higher in the endometrium than in the myometrium. In guinea-pigs ovariectomized at dioestrus the concentration was 3500 binding sites per diploid genome in the myometrium and 20300 in the endometrium; 1–3 days after oestradiol injection, this concentration was raised to 46000–38000 and 65000–83000 binding sites respectively. Thus the absolute rise was similar in both tissues but the relative increase was about 15-fold in the myometrium and only three- to fourfold in the endometrium. After injection of 2 mg progesterone, the concentration of receptor previously induced by oestrogen returned to very low values similar to those observed in non-hormonally treated controls.
This difference between endometrial and myometrial receptors could be due either to a faster turnover of the latter or to the existence of a stable non-hormonally controlled population of receptors, present only in the endometrium.
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Search for other papers by L. MARTIN in
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The duration of activity of a long-acting progestin, medroxyprogesterone acetate, was compared using three tests for progestational activity: the induction of stromal mitosis in the endometrium, implantation of blastocysts and inhibition of ovulation. The duration of activity was similar in each test and was longer when higher doses were given.
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Specific binding of progesterone in chicken oviduct (Sherman, Corvol & O'Malley, 1970) and in the rat and rabbit uterus (McGuire & DeDella, 1971; McGuire & Bariso, 1972) has been demonstrated (but see Milgrom & Baulieu, 1970). Evidence for the binding of progesterone in the human endometrium has also been reported (Wiest & Rao, 1971). The work presented here demonstrates the existence of a progesterone binder in the cytosol fraction of the human myometrium.
Tissues were removed during deliveries by Caesarean section, and placed in Krebs—Ringer bicarbonate medium (Batra & Daniel, 1970) at 25 °C. After dissecting away the endometrium, the myometrium was homogenized in sucrose—histidine solution (pH 7·4) and centrifuged as previously described (Batra, 1973). The supernatant was obtained after centrifugation at 110000 g . Samples (0·5 ml) of supernatant (about 2 mg protein) were incubated at 4 °C with 2 × 10-9 m-[3H]progesterone (0·05 μCi) in the
Search for other papers by R. J. LEVIN in
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It has been proposed that contact between the rat blastocyst and the endometrium is conditioned by like electrical charges on their membranes. Clemetson, Mallikarjuneswara, Moshfeghi, Carr & Wilds (1970) and Clemetson, Kim, Mallikarjuneswara & Wilds (1972) presented data purporting to show that treatment of rats with oestrogen or with progesterone could modify the potential of the endometrium and influence contact. Clemetson et al. (1970) stated that 'the high negative membrane potential under the influence of progesterone may be the cause of delayed implantation by repelling the negatively charged blastocyst. Conversely, the lowering of the negative membrane potential under oestrogen treatment could remove or reduce this repelling action and favour contact necessary for attachment and subsequent implantation.' The mechanism by which these changes in potential occurred was attributed to hormonally controlled alterations in the concentrations of sodium and potassium ions in the luminal and intracellular fluids of the endometrial cells. Clemetson
Search for other papers by R. GRATTAROLA in
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Marmorston, Crowley, Myers, Stern & Hopkins (1965) have reported that premenopausal women with breast cancer excreted significantly less androsterone and etiocholanolone than a control group. In an earlier paper Grattarola (1964) had found in such patients that endometrial specimens obtained before the menstrual period rarely showed a secretory pattern, a high percentage showing a moderate to a marked degree of proliferation. The urinary excretions of 11-deoxy-17-ketosteroids in premenopausal women with breast cancer was therefore studied with the aim of observing whether urinary excretion of androgen metabolites differs in patients with an ovulatory pattern of the premenstrual endometrium and patients with a proliferative or hyperplastic premenstrual endometrium showing that ovulation did not occur.
Thirty-two premenopausal patients with breast cancer, aged 30–47 yr., were examined. All had a breast removed 4–12 months before this study was started; all were free from metastases and none had been treated with hormones. Seventeen of these
Search for other papers by D. W. SCHOMBERG in
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Numerous experiments have now established that the life-span of the corpus luteum is regulated by the uterus in a number of species, including the pig (see review by Short, 1967). The regression of the corpus luteum during the normal oestrous cycle in the non-pregnant animal is dependent on the endometrium; the life-span of the corpus luteum can be maintained by removing the endometrium, or by transferring an embryo to the uterus.
Experiments of this nature have led to the concept of a uterine luteolytic hormone and numerous workers have attempted to demonstrate the existence of such a substance in uterine extracts without success save for one study in vitro (Duncan, Bowerman, Anderson, Hearn & Melampy, 1961). The reason for these failures may have been the inadequacy of the test systems used. Channing (1966) has recently shown that granulosa cells can be grown in tissue culture after harvesting them from the
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Search for other papers by J. M. ROBSON in
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SUMMARY
1. Furazolidone (0·75 g/kg) will interrupt pregnancy in mice.
2. Foetal tissue is particularly sensitive to the drug at the time of or before implantation of the ovum.
3. Intra-amniotic injection of furazolidone in rabbits causes foetal death and resorption.
4. Furazolidone applied locally does not antagonize the proliferative effect of progesterone on rabbit endometrium.
5. The mode of action of furazolidone on pregnancy is discussed. It is suggested that it acts directly on the foetus.
