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P. E. Mattner, B. W. Brown and J. R. S. Hales

Summary. Vessels with histological features characteristic of arterio–venous anastomoses were found in the stroma but not in CL. In 5 conscious ewes at the mid-luteal stage of the oestrous cycle, ovarian blood flow was significantly greater (P < 0·025) with microspheres of 50 than of 15 μm diameter in ovaries without CL (0·23 ± 0·04 (s.e.m.) and 0·11 ± 0·02 ml/min, respectively), but not in ovaries with CL (4·42 ± 0·86 and 3·73 ± 0·70 ml/min, respectively). In 5 similar but anaesthetized ewes, the portion of each ovarian artery within the ovarian vascular pedicle was bypassed with re-entrant catheters through which microspheres were perfused. A greater proportion (P < 0·01) of 50 than of 15 μm microspheres was retained in ovaries with (90 and 79%) or without (82 and 45%) a CL.

It is concluded that functional arterio–venous anastomoses are present in sheep ovaries.

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R. M. SHARPE, M. HARTOG, M. G. ELLWOOD and P. S. BROWN

The specific binding of radioiodinated HCG and LH by homogenates of adult rat testes in vitro has been demonstrated by Catt, Dufau & Tsuruhara (1972). The binding sites were of high affinity and the uptake of HCG was greatest at 24° C, maximum uptake occurring by 24 hr of incubation under these conditions (Catt, Tsuruhara & Dufau, 1972). There have been no reports of comparable work on the binding of LH by the testes of immature rats, but Means & Vaitukaitis (1972) have demonstrated a greater uptake of [3H]FSH in vitro by immature than by mature rat testes. Changes in the characteristics of the gonadal receptors for LH could be a factor in the control of sexual maturation. The binding of 131I-labelled human LH ([131I]hLH) by testicular homogenates from immature and mature Porton rats was therefore compared using the methods of Catt, Dufau & Tsuruhara (1972) and

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D. V. Brown, P. L. Senger, S. L. Stone, J. A. Froseth and W. C. Becker

The roles of selenium (Se) and glutathione peroxidase in reproductive function are poorly understood, but it is possible that they may be important for normal reproduction in the male. In rats fed a Se-deficient diet, the testes accumulated and retained more 75Se than did other tissues 1 week after injection (Brown & Burk, 1972; Burk, Brown, Seely & Scaief, 1972). Autoradiographic studies (Brown & Burk, 1972) of spermatozoa recovered from rat epididymides have shown that 75Se is associated with the midpiece of the spermatozoon. Gould (1970) has suggested that 75Se is probably incorporated into late spermatocytes or early spermatids in the rat. Rotruck et al. (1973) demonstrated that Se is a component of glutathione peroxidase, an enzyme which has been reported to exist in dog, goat, ram and human semen (Li, 1975). The objectives of the present study were to determine whether glutathione peroxidase is present in ejaculated bovine semen and the relationship of the enzyme levels to sperm concentration and ejaculate volume.

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A M Brown, J M Janik, E S Murphree, R King and P Callahan

The ability of steroid hormones to produce an LH or prolactin (PRL) surge was determined in rats ovariectomized at 6, 9 or 13 weeks of age and subjected to one, three or six cycles of estrogen and progesterone replacement. Sensitivity to steroid replacement was dependent on the age of the animal at the time of ovariectomy. Repeated cyclic steroid hormone replacement significantly increased the magnitude of the PRL response, but not the LH response, in animals ovariectomized at 6 weeks. The LH response was significantly altered by cyclic steroid replacement only in animals ovariectomized at 13 weeks. These results indicate that the mechanisms involved in the regulation of PRL secretion are influenced by steroid hormone replacement and that cyclic steroid hormone exposure increases the magnitude of the PRL secretory response.

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J. K. Voglmayr, N. A. Musto, S. K. Saksena, P. D. C. Brown-Woodman, P. B. Marley and I. G. White

Summary. A technique which permits collection of the total output of spermatozoa and fluid from the cauda epididymidis of conscious rams is described. The volume of epididymal semen collected varied in an approximately inverse proportion with the frequency of collection, but there was little variation in the concentration of spermatozoa. Chemical analyses showed that cell-free cauda epididymidis fluid contained lactic acid at various concentrations, only traces of glucose but relatively high amounts of phospholipid, pregnenolone, androgen-binding protein and 5α-dihydrotestosterone (5α-DHT).

Testicular spermatozoa maintained their metabolic activity and cellular integrity when stored in cauda epididymidis fluid in vitro at low temperature. After exposure to cauda epididymidis fluid for 14 days, testicular spermatozoa were predominantly glycolytic in their mode of glucose dissimilation and in this respect they resembled ejaculated spermatozoa.

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I. T. Cameron, A. P. Davenport, C. van Papendrop, P. J. Barker, N. S. Huskisson, R. S. Gilmour, M. J. Brown and S. K. Smith

Summary. Endothelin-like immunoreactivity (ET-IR) was detected immunocytochemically in glandular epithelium and vascular endothelium of human endometrium and myometrium. Primary antibody was raised in rabbits against the carboxy-terminal heptapeptide of endothelin 1 (ET-1), ET-1(15–21),and compared with antibodies raised against the cyclized amino-terminal, ET-1(2–13),and commercially obtained antibodies against the whole ET-1 or ET-3 molecule. Binding was visualized using the peroxidase technique in sections counter-stained with haemalum. Staining was seen in each of 15 sections from eight women in the proliferative (five) or secretory (three) phase of the cycle. Intense staining was present in the cytoplasm of endometrial glands and vascular endothelium, and was greatest at the endometrial–myometrial junction. The pattern of staining was similar with all primary antibodies tested. The demonstration of ET-IR in endometrium suggests that the endothelins may play a role in control of the uterine vascular bed.

Keywords: endothelin; endothelin-like immunoreactivity; endometrium; immunocytochemistry; human