Search PubMed⌕ Search

Biomedical subjects

N R Adams

Publications and source records attributed to N R Adams.

At least 73 records · Page 4Linked to original sources
PubMed1978

Changes in oestradiol-17beta binding in the hypothalami and pituitary glands of persistently infertile ewes previously exposed to oestrogenic subterranean clover: evidence of alterations to oestradiol receptors.

The binding of [3H]oestradiol-17beta to the hypothalamus and pituitary gland of clover-affected permanently infertile and control ovariectomized ewes was compared in vivo and in vitro. When [3H]oestradiol-17beta was infused into the carotid artery (10 ng/min), the total homogenate and the nuclear and protamine-precipitable cytosol fractions of hypothalami and pituitary glands from clover-affected ewes bound significantly more[3H]oestradiol than those of the controls. Cytoplasmic oestradiol-17beta receptors from the pituitary glands of clover-affected ewes showed a significantly lower apparent association constant and a higher number of binding sites/mg protein in vitro. It is suggested that the hypothalami and pituitary glands of ewes made permanently infertile by oestrogenic clover are less sensitive to feedback regulation of oestradiol-17beta at physiological levels.

Animals↗
PubMed1977

Morphological changes in the organs of ewes grazing oestrogenic subterranean clover.

The morphological effects of phytooestrogen exposure were determined in 10 ewes exposed to subterranean clover for 60 days, compared with 10 controls. In a second experiment, the time course of the development of the changes was studied. Typically oestrogenic changes were observed in ovary, oviduct, uterus, cervix, vagina and mammary glands. There was an early increase in cervical mucus, followed by a decrease. The delta basophils of the pituitary became degranulated, and hyperactive in appearance. The adrenal and thyroid glands increased in weight, and thyroid epithelium increased in height. There appeared to be a temporary increase in neurophysin storage in the hypothalamus, and shrunken, hyperchromatic neurones were observed in the hypothalamus of some affected ewes. All changes were observed within three weeks of exposure.

Adrenal Glands↗
PubMed1976

Cervical mucus changes in infertile ewes previously exposed to oestrogenic subterranean clover.

Characteristics of cervical mucus were compared between groups of ewes which had previously grazed for long periods on either potently oestrogenic clover pasture (group A), mildly oestrogenic pasture (group B) or non-oestrogenic pasture (group C). No phytooestrogens were fed at the time of the study. The chloride content of mucus from group A ewes was significantly decreased, on a dry weight basis. The motility and survival of ram spermatozoa appeared similar in cervical mucus from groups A and B. There was no statistically significant difference between groups of ewes in either the total wet weight of mucus, the proportion of dry weight, or the degree of arborisation of mucus, at the time of oestrus. Mucus from group A ewes had a significantly decreased spinbarkheit, and a decreased ability to orientate sperum migration, when compared with group B. The group B ewes had a significantly smaller spinbarkheit than group C. Measurement of cervical mucus spinbarkheit offers promise as a diagnostic test for permanent clover infertility.

Animal Feed↗
PubMed1975

The duration of the oestrous cycle of ewes affected with clover disease.

Oestrous cycles in ewes affected with clover disease were compared with those for control animals at two locations. Significantly fewer diseased ewes were observed in oestrus. There was a significant increase in variability of oestrous cycle duration in the diseased ewes at one location. Some of the cycle irregularities could be related to gross lesions in the internal genitalia. Despite these findings, there was no association between oestrous cycle abnormalities and previous fertility records, suggesting that they are of little consequence to the infertility of clover disease under field conditions.

Animals↗
PubMed1975

A pathological and bacteriological abattoir survey of the reproductive tracts of merino ewes in Western Australia.

Macroscopic examination of 487 ewe reproductive tracts from 18 different sources was made at Perth abattoirs. Of these, 194 were examined microscopically and 217 bacteriologically. Observations were made during March to May, when ewes were not grazing oestrogenic pasture. Significant lesions in ovaries or oviducts were rare. Macroscopic cysts were found in the uterus or cervix of 159 ewes (32.7%). Microscopic lesions, including uterine or cervical cysts and squamous metaplasia or goblet cell hyperplasia of the epithelium, were observed in 76% of ewes studied. Bacteria were isolated from 59 ewes, the most common genera being Corynebacterium, Escherichia, Streptococcus and Bacillus. Escherichia coli and streptococci appeared to be the most commonly associated with endometritis. Presence of bacteria was closely associated with endometritis and with cysts in the cervix. Endometritis was observed microscopically in 48 ewes (24%) and was significantly associated with the presence of cysts in the uterus or cervix. These results suggest that there is a high incidence of clover disease lesions in West Australian ewes, and that under commercial conditions clover disease may cause functional damage to the cervix, allowing passage of bacteria and resulting in endometritis.

Abattoirs↗