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J. I. RAESIDE

Summary.

The daily urinary excretion of oestrogens was measured by a chemical method, at weekly intervals through the greater part of gestation in two sows and during the last 6 weeks in four other sows. Oestrone appeared to be the principal component of the oestrogens in pregnant sows' urine. After an early peak in the 4th week from conception, the level of oestrone remained low until about the 10th week and then rose steadily to high levels at term.

Complete and continuous collection of urine, uncontaminated with faeces, was made from two sows for several days before parturition and from a total of five sows during, and for a few days after, parturition. A rapid decrease in urinary oestrogen excretion was seen after the sows had farrowed.

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J. I. RAESIDE

Summary.

A chemical method for estimating oestrogens in the urine of pigs (Raeside, 1963) was used to study the levels during the oestrous cycle. Complete and continuous urine collection, free from contamination with faeces, was carried out with two sows for about 4 weeks. The pattern for urinary oestrone showed a well defined peak, near the onset of oestrus, with a relatively sudden fall to levels which remained low until the approach of the next oestrus. The relation of the oestrone peak to oestrus was examined more closely in four sows, with estimations made on urine samples representing 8-hr periods during continuous collection. The findings suggest a preovulatory fall in oestrogen production in the sow. Less reliable estimations were obtained for the oestradiol fraction, and no quantitative results for oestradiol-17β are presented.

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J. I. Raeside

Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada N1G 2W2

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J. DUFOUR and J. I. RAESIDE

Histochemical methods have been widely used for the detection and localization of hydroxysteroid dehydrogenase activity, mainly in steroid-hormone producing organs and tissues (Baillie, Ferguson & Hart, 1966). Hay & Deane (1966) attempted to demonstrate Δ5-3 β- and 17 β-hydroxysteroid dehydrogenases in testicular tissue of the larger farm animals. In the adult boar, an intense staining reaction in the interstitial tissue of the testes, incubated without substrate added to the medium, prevented the histochemical demonstration of a specific reaction for Δ5-3 β-hydroxysteroid dehydrogenase. In view of the high production of both oestrogens and androgens by the adult males of this species (Raeside, 1965), it seemed of particular interest to be able to apply methods for the detection of hydroxysteroid dehydrogenase activity to testicular tissue of the adult boar.

Testes were obtained from two adult boars

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J. I. Raeside and K. Ronald

Summary. Blood samples were taken at weekly intervals during the last 2 months of pregnancy from a mature (7-year-old) harbour seal which had conceived and was kept in captivity. The concentrations of oestrone, oestrone sulphate, progesterone and glucocorticoids were determined by radioassays. The plasma levels of unconjugated oestrone were slightly greater than those of oestrone sulphate. Total oestrone declined steadily over the last month from a peak of 2·3 ng/ml at 30 days before parturition. Plasma progesterone concentrations rose to 61 ng/ml at 2 weeks before parturition and fell to about half that value by 2 days before birth of a normal male pup. Plasma glucocorticosteroids reached a peak of 164 ng/ml, also at 2 weeks, but showed only a slight decline thereafter. A higher value (392 ng/ml) was recorded 5 days after parturition.

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K. J. BETTERIDGE and J. I. RAESIDE

Summary.

In eleven sows studied during the normal oestrous cycle, cervical mucus was most abundant and free-flowing during prooestrus and early oestrus and showed peak arborization 2 days before the onset of oestrus. Four gilts approaching puberty did not show typical arborization patterns until just before the second oestrus. In nineteen pregnant sows, only ten of 429 smears showed arborization. Fluctuating levels of reducing substances were found in cervical mucus throughout the cycle with a tendency for levels to be higher near oestrus. An increase in reducing substances preceded the pubertal oestrus in two of four gilts. Stained cervical smears from eleven cycles showed neutrophils and epithelial cells throughout the cycle. Large, vacuolated epithelial cells were predominant during metoestrus.

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R. M. LIPTRAP and J. I. RAESIDE

It is well established that cryptorchidism is associated with degeneration of the seminiferous tubules, but there is less certain knowledge concerning the internal secretory capacity of the abdominal testis. Although unilaterally and bilaterally cryptorchid boars are able to excrete dehydroepiandrosterone (DHA) and oestrogens in amounts comparable to those of normal boars (Liptrap & Raeside, 1970), the abdominal testes of such animals show a limited response to gonadotrophin stimulation (Liptrap & Raeside, 1971). The purpose of the present study was to determine if the higher abdominal temperature was responsible, at least in part, for the limited response of the cryptorchid testis to stimulation by hcg, as reflected in the urinary excretion of DHA and oestrogens.

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R. M. LIPTRAP and J. I. RAESIDE

Summary.

Urinary excretion of dehydroepiandrosterone (DHA) and oestrogens was determined in five bilaterally cryptorchid boars and four unilaterally cryptorchid boars. Similar determinations were carried out in two boars made cryptorchid through surgery. The DHA and oestrogen values for the cryptorchid animals were comparable to normal boars of a similar age. These results suggest that the cryptorchid testes of the boar are capable of producing normal amounts of testicular steroid hormones.

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H. S. JOSHI and J. I. RAESIDE

Summary.

The effects of oestrogens on the activity of accessory sex glands were studied in castrated boars receiving testosterone continuously. Diethylstilboestrol (DES), 17β-oestradiol (E2) and oestrone (E1) were administered successively for 6-week periods which alternated with treatments of testosterone alone. Semen was collected twice each week and measurements were made of the total, the strained and the gel volumes. Citric acid and fructose contents of the seminal plasma were also determined. Highly significant (P<0·01) differences between boars were observed for all criteria in a series of collections made before castration.

Castration resulted in reduction in the total quantities of secretory products of the accessory sex glands. Subsequent treatment with testosterone alone for a period of 12 weeks had only a slight effect on their secretions. Supplementary treatment with DES, E2 or E1 significantly (P<0·01) increased the secretory activity of these glands from the levels in the respective preceding periods with testosterone alone. After withdrawal of oestrogens, the elevated levels of citric acid secretion remained high or increased further, while the amounts of seminal plasma and fructose continued at the higher levels or declined.

Oestrogens also had a synergistic effect with testosterone on improving the libido of castrated boars. The reaction time was decreased by 45% (P<0·01) during supplementary treatment with oestrone for 12 weeks.

The results of these experiments suggest that oestrogens act synergistically with testosterone on the accessory sex glands and on the sexual behaviour of the boar.

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R. M. LIPTRAP and J. I. RAESIDE

Summary.

Luteinizing hormone (lh) activity in blood was assessed by the ovarian cholesterol depletion (ocd) method and oestrogens were estimated chemically in the urine of seven sows before and during oestrus. In three sows, peritoneal cannulation permitted the time of ovulation to be related to lh and oestrogen determinations. The findings suggest a marked elevation of blood lh activity coincident with a peak of urinary oestrogen excretion, and occurring 40 to 48 hr before the time of ovulation.