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Search for other papers by T. G. BAKER in
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Rats were immunized against luteinizing hormone releasing hormone (LH-RH) and ovulation and follicular development were studied 12, 24 and 48 weeks later. The abolition of regular cyclic patterns of vaginal smears and the absence of luteal tissue in all but one of 32 rats showed that the immunization was effective in blocking ovulation. Follicular growth varied between rats and appeared to be dependent on whether the inhibition of LH-RH had been sufficient to affect the secretion of basal levels of gonadotrophins. Low levels of gonadotrophins were associated with poor follicular development, uterine atrophy and leucocytic vaginal smears, whereas levels of gonadotrophins similar to those in the dioestrous controls led to adequate follicular growth in the absence of ovulation, the production of cystic follicles, uterine stimulation and persistent vaginal oestrus. A group of rats was ovariectomized 12 weeks after immunization against LH-RH; animals with low antibody titres and large follicles responded with increases in the levels of LH and FSH in the blood, whereas in those with high antibody titres and little follicular development the concentrations of gonadotrophins remained low. The reproductive capacity of rats immunized against LH-RH was tested by caging them with normal male rats from 3 weeks after immunization. Although mating occurred in three rats during the first month, no offspring were produced. No matings occurred in the remaining 41 weeks.
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SUMMARY
The response of mouse ovaries maintained in organ culture to follicle-stimulating hormone (FSH), luteinizing hormone (LH) and human chorionic gonadotrophin (HCG) was assessed using quantitative histological and radioimmunoassay techniques.
In terms of the induction of preovulatory maturation in follicular oocytes, 1 μg FSH/ml medium was as effective as 10 μg LH/ml. The lowest doses of HCG and LH used (0·2 i.u./ml and 1 μg/ml respectively) had no effect on oocyte maturation, whereas the response to FSH was virtually unchanged irrespective of dose (1–10 μg/ml). When the level of progesterone in the medium at the end of organ culture was used as an index of ovarian response, LH was more effective than FSH and HCG, although all the hormones induced a significant increase, irrespective of dose.
These results are discussed in terms of the mode of action of gonadotrophins in the processes culminating in ovulation.
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Search for other papers by T. G. Baker in
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ABSTRACT
Reproductive tissues, steroid hormone secretion, and sexual behaviour have been examined in five gilts, in each of which the right gonad was an ovotestis. Although from different females, these animals were sired by the same boar and each possessed an XX sex chromosome constitution as determined by karyotype analysis of blood cells. Despite variable amounts of testicular tissue in the ovotestis and unilateral development of a prominent epididymis, four of the animals had oestrous cycles of normal duration (20–22 days) and extended periods of standing oestrus (3–6 days). The fifth animal did not have detectable oestrous cycles but was extremely aggressive in the presence of a mature boar. Two of the gilts were mated, and there were small numbers of embryos in each uterine horn 23 and 26 days later. Removal of the ovary did not prompt compensatory hypertrophy in the ovarian portion of the ovotestis, nor did injection of pregnant mare serum gonadotrophin stimulate detectable follicular growth in ovarian tissue adjoining testicular tissue.
Concerning the aetiology of this intersex condition, the unilateral appearance of an ovotestis precludes any simple involvement of a translocated portion of the Y chromosome or systemic effects of unusual titres of the putative H–Y antigen. However, bearing in mind a predisposition to gonadal asymmetry in eutherian mammals, a case is advanced for apposition or incorporation of adrenocortical tissue in the right embryonic ovary. The resultant virilization of neighbouring reproductive tissues would stem from adrenocortical androgen synthesis.
J. Endocr. (1985) 106, 233–242
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SUMMARY
Foetal human testes (12–22 weeks gestation), maintained in organ culture, were treated with human chorionic gonadotrophin (HCG) and the amount of testosterone produced compared with control cultures. In all cases the testes produced testosterone, but from the 13th to 18th week of gestation significantly more testosterone was produced by, and the Leydig cell hyperplasia was maintained in, the HCG stimulated organ cultures. It is suggested that HCG is ultimately responsible for differentiation of the human male external genitalia.
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Search for other papers by R. J. SCARAMUZZI in
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SUMMARY
The response of mouse ovaries maintained in organ culture to prostaglandin E2 (PGE2) and prostaglandin F2α (F2α) was assessed using quantitative histological and radioimmunoassay procedures.
Prostaglandin E2 induced histological changes in the cultured follicles comparable to those induced by human chorionic gonadotrophin (HCG) and the increase in the number of oocytes undergoing preovulatory maturation over the control value was the same irrespective of the treatment (PGE2 alone, HCG alone, or PGE2 + HCG). The amount of progesterone/ ml of culture medium was also significantly higher with these preparations than in control cultures (about 125 ng/ml compared with 57 ng/ml).
By contrast, 5 μg PGF2α/ml medium increased neither the number of oocytes undergoing maturation nor the concentration of progesterone in the culture medium. The latter increased when the dose of PGF2α was increased to 30 μg/ml, although the proportion of oocytes beyond the dictyate stage remained at the control level. There was no augmentation in the response (above the level for HCG alone) when HCG and PGF2α were added to the explant medium simultaneously. These results are discussed in terms of the possible mechanism of action of the various preparations.
