Search Results

You are looking at 1 - 10 of 23 items for

  • Author: G. M. H. WAITES x
Clear All Modify Search
Free access

T. G. Cooper and G. M. H. Waites

Summary. Controlled perfusion through the lumen of the distal cauda epididymidis in the anaesthetized rat has been explored as a means of examining physiological exchanges from blood across the epididymal epithelium. The mean length of the perfused, sperm-free, tubule was 14·5 cm (±1·5 s.e.m., n = 9). No cholesterol, protein or sialic acid was detected in the perfusate at flow rates exceeding 10 μl/min, but at rates of 0·4–1·2 μl/min, protein appeared at concentrations of 0·21–0·55 mg/ml (i.e. secretion rates of 0·21–0·83 μg/min; 3 rats). Glucose was detected at all perfusion rates (3–27 μl/min) at concentrations of 0·06–0·58 mm (0·8–6·8% blood levels).

During intravenous infusions of 3H2O, radioactivity in the perfusate rapidly attained 87% blood plasma concentrations; no radioactivity was detected when carboxy-[14C]dextran or methoxy-[3H]inulin were infused. Radioactivity appeared in the epididymal perfusate to 1–7% of blood levels during intravenous infusions of d-[U-14C]glucose or 3-O-methyl[1-3H]glucose.

This evidence suggests that the preparation is physiological and could be used to explore the dynamics of exchanges between blood and epididymis.

Free access

T. G. Cooper and G. M. H. Waites

Summary. When [3H]testosterone was infused into the general circulation of the rat, perfusion of a length of the cauda epididymidis (17 ± 1·0 (s.e.m.) cm, n = 36) with perfusates of varied composition revealed a low entry of radioactivity (1–10% plasma levels; 10 exps) with protein-free perfusates, and a greater entry (15–48%; 10 exps) when the perfusate contained bovine serum albumin (38 mg/ml). When the perfusate contained ovine or rat testicular fluid, or rat epididymal fluid at protein concentrations of 3 mg/ml or less, the entry of radioactivity into the epididymis was greater than when the perfusate contained 3 mg BSA/ml. The addition of ovine rete testis fluid protein (3 mg/ml) to BSA (38 mg/ml) in the perfusate increased the uptake of radioactivity (58–106%; 6 exps).

Radioactivity in blood was principally associated with testosterone (90, 95% total blood activity, 2 rats), whereas both [3H]testosterone (37, 41% total perfusate activity) and [3H]dihydrotestosterone (42, 63% total perfusate activity) were present in BSA-containing perfusates. The proportion of dihydrotestosterone appeared to increase when the perfusate contained protein of testicular origin.

Free access

G. R. MOULE and G. M. H. WAITES

Summary.

The semen collected from twelve Merino rams was examined before and after they were exposed during 3 days to two 6-hr periods in a climate room at 40·5° C, 8·5 mm Hg vapour pressure and 40·5° C, 31·5 mm Hg, respectively. Semen of decreased quality was collected from all the rams after this treatment. The change varied markedly in severity and duration and was related to the rise of the temperature of the subcutaneous tissue of the scrotum measured during the climate-room treatment and not to changes in rectal or flank-skin temperatures. The first ejaculate containing abnormal spermatozoa was collected 13 to 21 days after the treatment, and the concentration and total content of fructose in the semen of all rams started to rise at this time. The three rams which were most severely affected suffered a seminal degeneration which lasted for 35 to 39 days.

After recovery from the first experiment, the same rams were divided into three groups of four. Two groups were exposed to the same heat treatments as before and the third group stood in the climate room for 12 hr at 21° C and 6·8 mm Hg vapour pressure. Water at 17 to 19° C was circulated around the scrotum of one group of rams exposed to heat and of the group in the thermo-neutral environment. Only the rams exposed to heat without their scrota cooled in this way produced semen of inferior quality. It was concluded that under the conditions of these experiments, the efficiency of the heat-dissipating properties of the scrotum alone decided the magnitude of the adverse effects of short periods of raised air temperature on the quality of the semen produced by Merino rams.

Free access

G. M. H. WAITES and G. R. MOULE

Summary.

The pulsatile blood flow in the internal spermatic artery of the ram is changed by the arterial coils in the spermatic cord so that the testis receives a relatively pulseless blood flow at a lower mean pressure. The major pulse-pressure reduction occurs in the proximal one-third of the coiled length of the artery; in the distal two-thirds, the character of the coiling and structure of the artery change. These observations are discussed particularly in relation to the thermo-regulatory function previously suggested for the internal spermatic artery.

Free access

G. M. H. WAITES and G. R. MOULE

Summary.

The blood flowing through the internal spermatic artery of the ram has been shown to cool by 5.2°C (range 4.5° to 5.8°C) between the aorta and the dorsal pole of the testis when testicular temperatures are 33.3° to 34.7°C. Most of the cooling occurs in the coiled portion of the artery in the spermatic cord where the venous blood returning from the testis through the pampiniform plexus warms by a similar amount. It is concluded that the vascular arrangement in the spermatic cord of the ram is a remarkably efficient heat-exchange system.

The temperature deep in the testis remained close to that of the inside of the scrotal skin throughout controlled variations in the range 28° to 40°C. Changes in the temperature of the scrotum are quickly transferred to the blood in the superficial veins of the testis which then, by heat exchange in the spermatic cord, alters the temperature of the testicular arterial inflow. It is concluded that the vascular mechanism is not by itself regulatory but it rapidly transfers any benefit of scrotal thermoregulation to all parts of the testis.

Free access

S. J. Main and G. M. H. Waites

Summary. The integrity of the blood–testis barrier was investigated during and after local heating of rat testes sufficient to produce a temporary cessation of spermatogenesis. The flow, ionic composition and protein content of rete testis fluid (RTF) collected from testes maintained at 33 or 41°C were unaffected either at the time of treatment or up to 2 days later when the major cytological consequences of heating occurred. The normally low rate of transfer of albumin from blood to RTF was unaffected during and after heating. Transfer constants for radioactive K, Rb, Na and lysine consistently increased during heating although there were time-dependent differences between the patterns of response for each molecule. The normally rapid transfer of testosterone was unaffected by heating, but the entry rates of radioactivity into RTF after the infusion of more slowly diffusing steroids were enhanced at 41°C. The clearest effects of heating were an approximate doubling in the uptake of oxygen and decrease in the net synthesis of protein by the testis. It is concluded that heating sufficient to damage spermatogenesis was not associated with dramatic alterations in the integrity of the blood–testis barrier but more with changes in testicular metabolism.

Free access

N. Jenkins and G. M. H. Waites

Summary. The effect of the removal of one testis from cross-bred lambs at 1, 4, 8 or 12 weeks of age on plasma FSH, LH and testosterone was studied until 16 weeks of age. Hemicastration at all ages elicited a significant increase in plasma FSH compared to controls without a corresponding change in plasma LH or testosterone. The raised FSH after hemicastration at 1 or 4 weeks of age was suppressed to control levels between weeks 7 and 8; such a suppression was not observed in the 4 weeks following hemicastration at 8 or 12 weeks of age. The weight of the remaining testis had increased compared with the control by 12 weeks of age after hemicastration at 1 week ( + 69%), 4 weeks ( +13%) and 8 weeks (+ 40%); hemicastration at 12 weeks of age also resulted in growth of the remaining testis at 16 weeks ( +82%). The total androgen production of interstitial cells in response to ovine LH stimulation in vitro did not differ significantly between lambs of 1 and 12 weeks of age, or in animals of 4, 8 and 12 weeks of age after hemicastration at 1 week of age.

Subdermal implantation of oestradiol-17β into 1-week hemicastrated lambs at the time of operation or at 6 weeks of age increased plasma oestradiol concentrations by approximately 2–4-fold, prevented the FSH and testicular growth responses to hemicastration and suppressed plasma LH and testosterone to levels lower than those in control lambs. The total androgen response of interstitial cells from the remaining testis of oestradiol-implanted lambs at 12 weeks of age was significantly reduced.

We suggest that the pituitary—testis axis varies in sensitivity during the prepubertal period although the interstitial cellular response of the testis to LH stimulation remains constant.

Free access

B. P. SETCHELL and G. M. H. WAITES

Summary.

The concentration of spermatozoa in the rete testis fluid of rats increased gradually with age and reached adult levels at about 250 g body weight, whereas fluid secretion per unit weight of testis reached adult rates at a body weight of about 100 g. Unilateral castration had no effect on the weight of the remaining testis or on its fluid secretion; sperm concentration in rete testis fluid was only affected in very young rats. Local heating of the testes of rats was followed by a fall in the sperm concentration in rete testis fluid beginning between 6 and 10 days, and lasting until 39 days, after heating. This fall was associated with a decrease in testis weight which persisted after the concentration of spermatozoa in rete testis fluid had returned to normal. However, there was no change in fluid secretion per unit weight of testis, nor was there any change in the concentration of inositol, glycine or potassium in rete testis fluid.

Free access

G. M. H. WAITES and N. EINER-JENSEN

Department of Physiology and Biochemistry, The University, Reading RG6 2AJ, and The Population Council, The Rockefeller University, York Avenue and 66th Street, New York, NY. 10021, U.S.A.

(Received 6th September 1974)

Testicular spermatozoa are transported from the testis through the ductuli efferentes into the caput epididymidis in rete testis fluid (RTF). This fluid was first collected for analysis from conscious rams (Voglmayr, Waites & Setchell, 1966) and then from conscious bulls (Voglmayr, Larson & White, 1970) and anaesthetized wallabies (Setchell, 1970) by cannulation of the extratesticular rete through the ductuli efferentes. Rete testis fluid was then obtained from anaesthetized rats by inserting a side-hole catheter into the rete testis, 12 to 24 hr after ligating the ductuli efferentes (Tuck, Setchell, Waites & Young, 1970). Tuck et al. (1970) suggested that RTF is a mixture of two fluids; one, a highpotassium, low-protein fluid secreted in the seminiferous tubules, and the other,

Free access

B. P. SETCHELL and G. M. H. WAITES

The unusual complexity of the testicular blood vessels of eutherian mammals has been shown to have haemodynamic and thermoregulatory significance. The pulse wave of pressure passing down the long, coiled internal spermatic artery of the ram (Waites & Moule, 1960), dog (Blombery, Gow & Waites, unpublished observations) and rat (Setchell, 1969) is attenuated to a small oscillation, but mean blood pressure is only marginally reduced. A similar pressure-damping action was described for the carotid rete mirabile of the dolphin (Nagel, Morgane, McFarland & Galliano, 1968). There is also plentiful evidence for countercurrent heat exchange between neighbouring arteries and veins (see Waites, 1969). As the spermatic veins closely surround the internal spermatic artery, Harrison & Weiner (1949) proposed that heat exchange was occurring between the counterflowing blood streams. This was confirmed by measuring the thermal gradients in the testicular circulation of dogs (Dahl & Herrick, 1959) and rams (Waites