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Departments of Anatomy and Obstetrics and Gynecology, Louisiana State University Medical Center, New Orleans, Louisiana 70112, U.S.A.
(Received 22 April 1976)
The albino rat ovulates 15–18 h after parturition during the dark period (Johnson, Zarrow & Denenberg, 1974) and the hormonal interrelationship preceding this post-partum ovulation is similar to that found at pro-oestrus in the normal cycle (Labhsetwar & Watson, 1974). Chatterjee & Greenwald (1971) have shown that unilateral ovariectomy of pregnant rats on days 1, 10 or 15 produces increased numbers of antral follicles within 5 days and compensatory ovulation at the post-partum oestrus. The specific time after which the pregnant rat can no longer respond to unilateral ovariectomy by increasing the number of ova shed from the remaining ovary at the post-partum ovulation has not previously been evaluated. The present experiments were therefore designed to determine this time. Furthermore, such findings would elucidate, physiologically, when those follicles which
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Department of Anatomy, Louisiana State University Medical Center, New Orleans, Louisiana 70112, U.S.A.
(Received 12 April 1977)
It is known that a functional interaction exists between the adrenal and ovarian systems, albeit complex and not well understood. Removal of progesterone derived from the adrenal gland disrupts the synchronous discharge of luteinizing hormone (LH) and consequently the events associated with reproduction (Mann, Korowitz & Barraclough, 1975). Adrenalectomy of female rats also delays the onset of puberty, disrupts the normal oestrous cycle and decreases the number of ova shed and the size of the litter (Ramaley, 1974). Previously we reported that unilaterally ovariectomized rats which had been bilaterally adrenalectomized for 30 days did not, after one oestrous cycle, show compensatory ovulation or ovarian hypertrophy; rats adrenalectomized and ovariectomized for 30 days did, however, display both phenomena (Peppler & Jacobs, 1976). While continuing these studies on adrenal gland–ovary interrelationships, we collected data which
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Evidence indicates that the ovarian regulatory mechanism of different strains of rat may respond differently to adrenalectomy; this study examined that possibility.
Adult female Sprague–Dawley and Holtzman rats were maintained under constant environmental conditions and each strain was divided into groups: intact; adrenalectomized; unilaterally ovariectomized; adrenalectomized and unilaterally ovariectomized for 30 days; adrenalectomized 30 days previously and then unilaterally ovariectomized followed by one oestrous cycle; adrenalectomized 30 days previously and then unilaterally ovariectomized followed by one oestrous cycle with progesterone treatment (2 mg); adrenalectomized 30 days previously and then unilaterally ovariectomized followed by one oestrous cycle with corticosterone treatment (2·5 mg/100 g). All operations and autopsies were performed at metoestrus. Chronically adrenalectomized rats shed fewer ova per ovary than intact animals. Rats that had been unilaterally ovariectomized or adrenalectomized and unilaterally ovariectomized for 30 days showed compensatory ovulation as compared with intact rats and rats adrenalectomized for 30 days. Only the Sprague–Dawley rats that were adrenalectomized for 30 days and unilaterally ovariectomized for one oestrous cycle demonstrated compensatory ovulation. The remaining ovary in similarly treated Holtzman rats failed to compensate. Neither progesterone nor corticosterone influenced compensatory ovulation in the Sprague–Dawley rats, but both hormones caused an increase in the number of eggs ovulated in the Holtzman animals. In conclusion, the results of this study indicated that there is a strain-specific responsiveness of the ovary to adrenalectomy as assessed by compensatory ovulation.
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Departments of Anatomy and Obstetrics and Gynecology, Louisiana State University Medical Center, New Orleans, Louisiana 70112, U.S.A.
(Received 31 January 1975)
The results of investigations on the effect of unilateral ovariectomy (ULO) in the hypothyroid rat are conflicting because increase in weight of the remaining ovary has been used as the endpoint (Schreiber, Zbuzkova-Kmentova & Zbuzek, 1968; Saiduddin, 1972). A more reliable indication of ovarian function is to determine the number of eggs shed. After ULO, twice as many ova as normal are ovulated from the remaining ovary (Peppier & Greenwald, 1970). In this report the effect of thyroidectomy for either 2 or 7 weeks on the pituitary-ovarian relationship in the rat was studied using the phenomenon of compensatory ovulation after ULO.
Virgin, female, Charles River rats were used in two separate experiments. Thyroid glands were surgically removed at 59 days of age under ether anaesthesia. In the first experiment