Reproduction

KERR, J. B.; DE KRETSER, D. M.

doi: 10.1530/jrf.0.0430001pmid: 1127625

Summary.The formation, distribution and fate of lipid inclusions within the seminiferous tubules of the rat has been studied throughout the spermatogenic cycle. The occurrence of lipid inclusions within the Sertoli cell exhibited cyclic variation with the stages of the rat seminiferous cycle. At stage 9 of the cycle, residual bodies of maturing spermatids were phagocytosed by the Sertoli cell and released numerous lipid droplets which appeared to coalesce into large inclusions at the base of the Sertoli cell at stage 10. The Sertoli cell lipid inclusions persisted throughout the completion of meiosis (stages 11 to 14) and the formation of young spermatids (stages 1 to 2) and their numbers appeared to reach a peak at stages 12 to 13 of the cycle. The inclusions decreased markedly within the Sertoli cell cytoplasm during stage 2 and remained low until stage 9 when lipid from the residual bodies again became available to the cell. This cyclic variation of lipid inclusions within the Sertoli cell does not support previously held views that there is a gradual decline in Sertoli cell lipid during stages 10 to 14 of the spermatogenic cycle. A hitherto unnoticed finding was the presence of large lipid inclusions in the cytoplasm of late pachytene to diakinetic spermatocytes, and some observations suggest a transfer of these lipid inclusions from the Sertoli cells to primary spermatocytes.

JAGIELLO, GEORGIANA; DUCAYEN, MERCEDES; MILLER, W.; GRAFFEO, J.; FANG, J. S.

doi: 10.1530/jrf.0.0430009pmid: 165291

Summary.Utilizing some known physiological preovulatory hormone levels and specific cytological end-points, experiments were carried out with two different media to obtain a clearer understanding of meiotic maturation in vitro of ewe, cow, monkey and human oocytes. In the first series of experiments, it was shown that, in McCoy's medium, ovine LH, prostaglandin E1 and ovine prolactin increased the percentage of divisions of ewe oocytes, without cAMP as a demonstrable intermediate. Monkey oocytes incubated in McCoy's medium with fetal calf serum were stimulated by ovine LH, prostaglandin E2 or cAMP. Human oocytes were stimulated to divide in Diploid medium by ovine LH, oestradiol-17β with LH added later, or prostaglandin E1. Diploid medium containing added sheep serum markedly inhibited the meiotic activity of ewe oocytes when ovine LH, HCG, cAMP, prostaglandin E1 and E2 or prolactin were added. This effect was studied by separating the contained fetal calf and sheep sera. It was noted that when LH, HCG or prostaglandins E1 and E2 were added to a system utilizing fetal calf serum, only spontaneous resumption of meiosis occurred: stimulated and spontaneous activity were reduced when cAMP or prolactin were added. The inhibition of ewe oocyte maturation in Diploid medium with sheep serum and additives was also seen with cow oocytes incubated in Diploid medium containing fetal calf serum and LH, HCG, cAMP or prostaglandin E1 and E2. Cow oocytes incubated in McCoy's medium with equivalent fetal calf serum and added LH were sharply inhibited but spontaneous maturation persisted in the presence of added HCG, cAMP or bovine prolactin.

RUCKEBUSCH, Y.; BAYARD, F.

doi: 10.1530/jrf.0.0430023pmid: 1168710

Summary.Recordings of electrical activity of the oviduct and uterus were obtained during three oestrous cycles in cows fitted with an extracellular multi-electrode assembly. The stages of the cycle were identified by the appearance of the cervico-vaginal secretions and changes in the peripheral plasma level of progesterone were determined by radioimmunoassay.A gradual transition from local non-propagating electrical activity to propagating electrical activity with increase in the duration of contractions and then of their amplitude occurred 48 hr before the onset of oestrus. The transition coincided with a rapid decrease in progesterone level from 5 to 10 ng/ml to less than 0·1 to 0·4 ng/ml. This phenomenon was recorded from all uterine electrode sites, but was most marked at the uterotubal junction.Two days before oestrus, trains of potentials and bursts of activity became progressively grouped, apparently randomly, into prolonged phases in the distal portion of the oviduct and over the entire myometrium. During oestrus, the phases of activity became synchronized at these sites and both their amplitude and frequency reached a maximum. The strength but not the frequency of the phases diminished progressively 3 days after oestrus, followed by relative inactivity. The last remaining zone of activity was the uterotubal junction.During oestrus, the activities of the oviduct and the uterus were modified by oxytocin and adrenaline, the effect of the former being more marked on the uterus and that of the latter on the oviduct.

MANECKJEE, RHODA; MOUDGAL, N. R.

doi: 10.1530/jrf.0.0430033pmid: 1127638

Summary.The interrelationship between prolactin and LH in the maintenance of pregnancy during lactation was studied. The reduction of suckled young from eight to two or less, as late as on the morning of Day 4 of pregnancy, resulted in normal implantation. Reintroduction of eight young on Day 4 to lactating pregnant rats deprived of their litters on Day 1 resulted in an inhibition of implantation, but reintroduction on Days 5 or 6 did not inhibit implantation. If oestrogen, HCG or PMSG was given on Day 4 of pregnancy, implantation was induced at the normal time in rats suckling large litters. When LH antiserum was given on the morning of Day 4 or Day 8 to pregnant rats suckling two young each, it blocked implantation and postimplantation survival of blastocysts, respectively. When the number of suckling young was increased from two to eight on Day 6, however, LH antiserum blocked pregnancy only to the extent of 70%. Prolactin administered during the preimplantation phase inhibited implantation in pregnant rats suckling a minimum number of young, but had no effect when given during the postimplantation phase. Progesterone failed to block implantation. Prolactin had no inhibitory effect on implantation in the absence of the suckling stimulus or in non-lactating pregnant rats. The inhibition of implantation by prolactin in rats suckling two young could be effectively reversed by the administration of oestrogen, PMSG or HCG on Day 4 of pregnancy.

MAYNARD, P. V.; ELSTEIN, MAX; CHANDLER, J. A.

doi: 10.1530/jrf.0.0430041pmid: 1127639

Summary.Examination of intact individual human spermatozoa by X-ray microanalysis revealed that there was a correlation between particular elements in different regions of the cell. There was a constancy in the ratios of sodium to potassium in the head and mid-piece and of calcium to phosphorus in the mid-piece in any one sample, though the ratios varied between samples. This may have reflected the external environment since immersion in culture medium or cervical mucus had little effect on motility, yet markedly altered the sodium:potassium ratio.Incubation with copper wire in semen or cervical mucus significantly reduced the subcellular levels of both sodium and potassium in spermatozoa but did not affect the ratio between these two elements. The metal also displaced zinc from the head region, possibly replacing it by copper. This may account for the decreased motility of spermatozoa in contact with copper ions.The observed toxicity of copper for human sperm cells lends support to the theory that part of the mode of action of the copper IUD may be due to an alteration in sperm fertilizing potential. Although the level of copper released by IUDs containing 200 mm2 of copper wire exerted a minor toxic effect on spermatozoa, the elemental changes observed here may have great significance in the development of more efficient copper-releasing IUDs or an intracervical device whose action would depend on its spermatotoxic effect.

PULKKINEN, PIRKKO; KANERVA, SIRKKA; ELFVING, K.; JÄNNE, J.

doi: 10.1530/jrf.0.0430049pmid: 805236

Summary.Human spermatozoa, separated from the seminal plasma, contained substantial amounts of spermine, and also a distinct diamine oxidase (EC 1.4.3.6) activity. Spermine, but not diamine oxidase activity, could be removed from the spermatozoa by washing the cells with buffers containing high concentrations of salts. Incubation of human spermatozoa in the presence of labelled spermine and partly purified amine oxidase from bovine blood gave rise to the formation of radioactive products that could not be removed from the spermatozoa by increasing the ionic strength. Similarly, partly purified diamine oxidase from human seminal plasma apparently catalysed the formation of labelled products from radioactive spermine that were more tightly bound to the spermatozoa than spermine itself.

YUTHASASTRAKOSOL, P.; PALMER, W. M.; HOWLAND, B. E.

doi: 10.1530/jrf.0.0430057pmid: 1168711

Summary.Jugular vein blood was collected daily from four mature ewes throughout anoestrus and the first oestrous cycle of the breeding season until 4 days after the second oestrus. The levels of oestrogen, progesterone and LH were determined by radioimmunoassay. There were fluctuations in the LH level throughout most of the observed anoestrous period with a mean±S.E. value of 2·3±0·9 ng/ml. High LH values of 20·0, 41·2 and 137·5 ng/ml were observed in three ewes on Day −24 of anoestrus. A brief minor rise in progesterone level was also observed around this period. Progesterone levels were consistently low (0·11±0·01 ng/ml) before Day −25 of anoestrus. A major rise occurred on Day −12 of anoestrus and this was followed by patterns similar to those that have been previously reported for the oestrous cycle of the ewe. Random fluctuations of oestrogens deviating from a mean level of 4·40±0·1 pg/ml were observed during anoestrus and the mean level during the period from the first to the second oestrus was 5·2±0·3 pg/ml. A well-defined peak of 13·3±0·7 pg/ml was seen in all ewes on the day of the second oestrus. Results of the present study suggest that episodic releases of LH occur during anoestrus and periods of low luteal activity. The fluctuations in LH levels, as observed during the period of low luteal activity, i.e. before Day −25 of anoestrus, were less pronounced during the periods of high luteal activity. The view that luteal activity precedes the first behavioural oestrus of the breeding season is supported.

GURAYA, S. S.

doi: 10.1530/jrf.0.0430067pmid: 1127640

Summary.Lipid changes were studied histochemically in rat CL during the oestrous cycle, pregnancy and lactation after treatment with oestradiol benzoate (EB), LH and prolactin. A single injection of 50 μg EB given on any day during the first half of the oestrous cycle, pregnancy and lactation caused a heavy accumulation of lipid droplets, which consisted mainly of cholesterol and/or its esters, triglycerides and some phospholipids. If the treatment with EB was followed by a single injection of 20 i.u. prolactin, droplet accumulation either did not occur, or was greatly reduced. During the second half of pregnancy, a massive accumulation of cholesterol- and triglyceride-positive lipid droplets occurred in the CL of untreated rats, and prolactin was equally effective in reducing, or preventing the storage of cholesterol-positive lipid droplets. Prolactin was more effective if two injections of 10 i.u. were given daily after an interval of 11 to 12 hr. No appreciable lipid change in the CL was caused by injection of 100 μg LH on any day during the first half of the oestrous cycle and pregnancy, but during lactation the same amount caused a heavy accumulation of lipid droplets, consisting mainly of cholesterol and/or its esters, triglycerides and very little phospholipid. Persisting CL of pregnancy and cyclic CL seen during lactation and pregnancy, respectively, were unresponsive to exogenous hormones, apparently due to ageing as no lipid changes occurred in the CL after hormonal treatment.The results are discussed in relation to previous histochemical and biochemical studies and suggest that both LH and prolactin regulate the lipid and cholesterol metabolism in the luteal cells of the rat.

CHAUDHURI, G.

doi: 10.1530/jrf.0.0430077pmid: 1127641

Summary.An IUD inserted into one uterine horn caused an increase in its weight when this was compared with that of the contralateral control horn in rats. Such an increase could be partly prevented by treating the animals with indomethacin and aspirin. It is suggested that the IUD-induced increase in weight is at least in part mediated by release of prostaglandins.

GINSBERG, L.; HILLMAN, NINA

doi: 10.1530/jrf.0.0430083pmid: 1168712

Summary.The actual and potential activities of the cytochrome system were studied in cleavage-stage mouse embryos. Activities were determined by assaying embryos for total ATP and the rates of [32P]ATP synthesis both before and after their incubation in medium supplemented either with an energy coupling site inhibitor (antimycin, amytal or cyanide) or with the FADH-linked substrate, succinate. The data indicate that there are three major shifts in the mode of ATP production during preimplantation stages: the first, between the two-cell and late four-cell stages; the second, between the eight-cell and late morula stages; and the third, between the late morula and late blastocyst stages. These data are discussed in relation to studies on the energy metabolism of cleavage and blastocyst stage mouse embryos.