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Search for other papers by R. DEANESLY in
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SUMMARY
Cadmium chloride, in a single subcutaneous injection, can destroy spermatogenic and interstitial cells in the rat testis (Pařízek, 1957) and produce changes in the pituitary. The interstitial tissue is restored by ingrowths from the tunica and full androgen secretion returns before there is any regeneration of germinal epithelium.
A cytological study has been made of the peripheral and central pituitary gonadotrophs; the latter revert almost to normal as the interstitial tissue regenerates, whereas the former retain characteristic castration features, unless there is also regeneration of the germinal epithelium. This seems to indicate that in the normal testis there is a hormone contribution from the seminiferous tubules as well as from the interstitial cells.
The long-term effects of cadmium on the testis depend on the dose. Early stages of tubule restoration have been studied, but after administration of 0·9 mg., actual proliferation of the germinal epithelium was rarely found—only in four out of twenty rats, 113 or 142 days after injection.
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Search for other papers by R. DEANESLY in
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SUMMARY
Progesterone was isolated from systemic and uterine venous plasma and from placental tissue of intact and ovariectomized pregnant guinea-pigs. It was measured quantitatively by fluorescence assay.
Concentrations of progesterone in intact animals rose from a mean value of 64 ng./ml. plasma 11–16 days post coitum (p.c.) to reach their highest values (265 ng./ml.) 30–45 days p.c. and decreased to 140 ng./ml. immediately before parturition. In pregnant guinea-pigs, ovariectomized 28 days p.c. or later, the progesterone levels were lower (75 ng./ml. at 34–35 days p.c., 146 ng./ml. at 40–45 and 50–55 days p.c.) except at the end of pregnancy (165 ng./ml.). During the last 2 weeks of pregnancy the difference in the progesterone levels of the two groups was not statistically significant.
In ovariectomized pregnant guinea-pigs, the progesterone level was high in the uterine vein but low in placental tissue. The mean wet weight of placentae was, however, significantly correlated with systemic progesterone values.
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Search for other papers by A. S. PARKES in
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Search for other papers by R. DEANESLY in
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Search for other papers by A. S. PARKES in
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Search for other papers by J. S. PERRY in
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SUMMARY
Interruption of the prolonged luteal phase in hysterectomized guinea-pigs, followed by vaginal opening, can be caused by substances affecting the hypothalamus and hypophysis, which check gonadotrophin output. In the present experiments, both progesterone and reserpine were effective and caused regression of the corpora lutea. It may be concluded that in the guinea-pig, as in the sow and the sheep, the corpora lutea of hysterectomy do not function independently of the hypophysis.
The uterine factor associated with normal cyclic corpora lutea regression, which is lacking after hysterectomy, presumably acts on the hypophysis rather than directly on the corpora lutea.
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