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  • Author: J. P. KENNEDY x
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The effects of age and of parity on reproductive capacity were estimated by comparing old virgin with young virgin mice, and old parous with old virgin mice, respectively.

Increased age was associated with a greater body weight at `joining', a smaller proportion of mice pregnant, a greater number of cl of pregnancy, a greater number of implantation sites at Day 5 or 6 of pregnancy, a greater number of viable fetuses at Day 18 of pregnancy, and a smaller proportion of cl represented as implantation sites at Day 5 or 6 of pregnancy.

Parity significantly increased body weight at `joining' and the number of cl of pregnancy. The number of implantation sites at Day 5 or 6 of pregnancy and the number of viable fetuses at Day 18 of pregnancy were non-significantly greater for old parous than old virgin mice.

It was concluded from the relationships between body weight at `joining' and the number of cl of pregnancy that the age and parity effects on the numbers of cl, implantation sites and viable fetuses were due to differences between groups in body weight at mating.

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The growth and development, between birth and 33 weeks of age, of the ovaries, uterus and pituitary of Merino lambs were studied at approximately monthly intervals. The ovarian weight at 4 and 8 weeks of age was 6·8 and 10·8 times, respectively, the ovarian weight at birth. At 12 weeks, it had declined significantly and then remained relatively constant to 33 weeks. The uterine weight at 4 weeks was approximately twice the weight at birth, but it did not increase significantly again until 33 weeks. There was a small increase in pituitary weight between 4 and 8 weeks but no significant change thereafter.

The mean numbers of growing and vesicular follicles in the ovaries were 455±62 and 935±208, respectively, at birth. They increased significantly at 4 weeks, then declined significantly in older lambs. Mean diameters of the largest follicle per ovary and per animal increased steadily from birth to 33 weeks.

Oestradiol-17α was detected, by thin-layer chromatography, in the urine of all newborn lambs and oestradiol-17β was detected in the urine of one newborn lamb. After birth, oestrogens were not detectable in urine until 33 weeks when oestradiol-17α was found in two lambs and oestradiol-17β in another.

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P. M. Squires, S. J. Dixon and T. G. Kennedy

Studies were performed to determine whether the inhibition of the decidual cell reaction induced by intrauterine infusion of the angiotensin converting enzyme inhibitor enalaprilat in rats is reversed by activation of Ca2+ influx. Influx of Ca2+ was shown to be stimulated by angiotensin II in endometrial cells in this study. Ovariectomized, adult female rats were sensitized for the decidual cell reaction with steroid treatments. For experiments in vivo, intrauterine infusions of enalaprilat alone, or in combination with the Ca2+ ionophore A23187, a synthetic diacylglycerol, and dioctanoyl-sn-glycerol (diC8), and PGE2 were initiated on the day of uterine sensitivity. Enalaprilat inhibited the increases in uterine PG concentrations and uterine weight that occur following infusion of the vehicle. Concurrent infusion of A23187 partially, but not completely, reversed the inhibition of uterine weight increase; diC8 did not affect the inhibition of enalaprilat. A23187 did not reverse the effects of enalaprilat on uterine PG concentrations. Concurrent infusion of A23187 and PGE2 fully reversed the inhibitory effect of enalaprilat on uterine weight. For experiments in vitro, endometrial stromal and epithelial cells were obtained from uteri on the day of sensitivity and maintained in suspension. Cytosolic free calcium concentration ([Ca2+]i) was monitored in cell suspensions by fluorescence spectrophotometry using the Ca2+-sensitive probe, indo-1. Angiotensin II induced a transient increase in [Ca2+]i of endometrial stromal cell suspensions, but not of epithelial cells; PGE2 did not increase [Ca2+]i in stromal or epithelial cells. The effect of angiotensin II on stromal cell [Ca2+]i occurred in the absence of extracellular Ca2+ and was blocked by pretreatment of the suspensions with the angiotensin II antagonist, saralasin. Maximal decidualization in rats appears to require the interaction of separate Ca2+-dependent and PG-dependent processes, both of which may involve angiotensin II.

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The effect of hysterectomy on ovarian activity was studied in four mares. The cyclic secretion pattern of plasma progestins normally observed in the intact mare was interrupted by hysterectomy. Follicular activity was observed in all four hysterectomized mares, in spite of prolonged luteal activity, with a large number of follicles attaining ovulatory size without the occurrence of ovulation. Some ovulations were observed at irregular intervals in two out of four hysterectomized mares in spite of plasma progestin levels which ranged from 2 to 6 ng/ml. While all ovulations which occurred in the hysterectomized mares were followed by the formation of CL as determined by palpation per rectum, the rise of progestins in the peripheral plasma was variable as significant increases followed CL formation in some instances but not in others. Four mares had CL with functional life spans of 48, 74, 75 and 77 days at the time the experiment was terminated. There was no difference in the ability of the CL formed following these ovulations to convert pregnenolone to progesterone (per unit weight) as compared to CL of 9 days duration. The longest estimated CL life span in any hysterectomized mare was 137 days. Sexual receptivity did not occur in conjunction with follicular growth and ovulation in the hysterectomized mares in the presence of an active CL.