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N Meusy-Dessolle

Publications and source records attributed to N Meusy-Dessolle.

13 recordsLinked to original sources
PubMed1992

Immunohistochemical demonstration of melatonin in the female mink harderian gland.

In the Harderian gland of the female mink, either intact or killed after a bilateral ablation of the cervical superior ganglion, almost all of the cells of the alveoli were immunolabeled with anti-melatonin antiserum. Animals were killed during the day or during the night. The immunolabelling was observed only in the cytoplasm, while the nucleus remained unstained. Using successive dilutions of the antiserum on serial sections of the Harderian gland to qualitate the melatonin content, a circadian rhythm of melatonin immunoreactivity was observed. The intensity of immunofluorescence labelling was higher in intact animals killed during the day than in those killed during the night. These results could be explained by the inhibitory or stimulatory influence of pineal melatonin released during the night on melatonin synthesis or release in the Harderian gland, respectively. In the Harderian gland of ganglionectomized animals, the intensity of melatonin immunofluorescence was lower than in intact animals killed during the day. It is concluded that the Harderian gland might be involved in the perception of the day/night cycle and that melatonin synthesis/secretion was likely controlled by the cervical superior ganglion in this organ.

Animals↗
PubMed1989

Immunohistochemical demonstration and radioimmunoassay of melatonin in the mink pineal gland.

An antiserum raised against N-amino-3-propyl melatonin bound to a protein carrier was used to visualize melatonin by immunohistochemistry and to measure melatonin concentration by radioimmunoassay in the pineal gland of intact mink females killed throughout the 24 h cycle and females killed after a bilateral ablation of the cervical superior ganglion. Melatonin immunoreactivity revealed by immunofluorescence or by the peroxidase-antiperoxidase complex was observed in the cytoplasm of presumed pinealocytes of all the females. Circadian changes in pineal melatonin content were not visualized by immunohistochemistry; furthermore, immunoreactivity was also present in the pineal gland of the ganglionectomized females. However, the melatonin content measured by radioimmunoassay was significantly higher in the pineal gland from intact females killed during the night compared with that of intact females killed during the day or of ganglionectomized females. The discrepancy between the results obtained using the two methods may arise because immunohistochemistry can detect very small amounts of melatonin.

Animals↗
PubMed1985

Plasma concentrations of testosterone, dihydrotestosterone, delta 4-androstenedione, dehydroepiandrosterone and oestradiol-17 beta in the crab-eating monkey (Macaca fascicularis) from birth to adulthood.

Plasma testosterone, 5 alpha-dihydrotestosterone (DHT), delta 4-androstenedione, dehydroepiandrosterone (DHA) and oestradiol-17 beta concentrations of crab-eating macaques after birth were analysed by RIA. The profiles of plasma testosterone and DHT exhibited four phases: (1) a neonatal phase (0 to 3-4 months of age) with considerable synthetic testicular activity; (2) a phase of 'infancy' (generally up to 29 months of age) during which the values of both androgens were low; (3) a prepubertal phase (generally up to 43 months of age) when circulating values oscillated with wider individual variations, and (4) a pubertal phase when the concentrations increased in parallel and concomittantly with the onset of meiosis and the establishment of spermatogenesis. The testosterone values continued to increase, reaching adult values at about 5-6 years of age, whereas DHT levels tended to stabilize from 4-5 years. Relatively high androstenedione values during the neonatal phase decreased progressively until puberty, then increased again slowly up to the adult stage when they plateaued at about neonatal levels. The DHA levels were high during the first months, decreased at about 1 year, remained stable during infancy and prepuberty and then declined again during puberty. At about 5 years, the values were 28% of those in neonates. There was no evidence of an adrenarche before the first signs of sexual maturity were observed. Oestradiol-17 beta concentrations were high at birth and until 3 months, then decreased and remained steady from 1 year of age until adulthood, except at the onset of puberty (27-30 months of age) when high values were again noted. Our results show that, during the neonatal period, the testis exhibited considerable secretory activity.

Aging↗
PubMed1984

Relationships between Leydig cell morphometry and plasma testosterone during postnatal development of the monkey, Macaca fascicularis.

In neonates (0 to 3-4 months), the testis contained a mean number of 4.6 X 10(6) Leydig cells representing 4.2 % of its volume; Leydig cell cytoplasm contained 10.2 % of SER. In infants (up to 45 months), Leydig cells regressed but their number increased; their volume density did not change. Leydig cell cytoplasmic volume (454 microns3 ), which was about 2.5-fold less than in neonates (1 119 microns3 ) or adults (1 170 microns3 ), contained only 8.7% of SER. During meiosis stage (38-52 months). Leydig cell numbers and volume density did not vary but the cells reached a maximal size and an amount of SER comparable with that at birth was measured. When spermatogenesis was complete, the Leydig cells represented no more than 0.8% of testis volume, but their number and SER content were significantly increased. Except for a significant decrease when spermatogenesis was completed, Leydig cell lipid content did not change during development, and the volume density of mitochondria did not vary. The mean level of plasma testosterone was 2 ng/ml in neonates and 0.4 ng/ml in infants; it increased to 3 ng/ml during onset of meiosis and reached 10 ng/ml in adults. The profile of testosterone was positively and significantly correlated with the total volume and total number of Leydig cells (P less than 0.01 and P less than 0.02, respectively) and with changes in their cytoplasmic volume (P less than 0.001). Moreover, plasma testosterone levels were positively and significantly correlated with changes in Leydig cell SER content i.e. SER volume density and mean absolute volume per cell (P less than 0.001), total SER in the whole testis (P less than 0.01).

Aging↗
PubMed1984

Quantitative study of testis histology and plasma androgens at onset of spermatogenesis in the prepuberal laboratory-born macaque (Macaca fascicularis).

Laboratory-born Macaca fascicularis underwent successive testicular biopsies and peripheral blood sampling during the peripuberal age. Testicular fragments were studied quantitatively on seminiferous cord or tubule histological cross sections. Plasma testosterone, androstenedione, and dihydrotestosterone were quantified by RIA. Enlargement of the diameter of seminiferous cords or tubules resulted from the increasing number of spermatocytes and the formation of the lumen. The number of Sertoli cells per cord or tubule cross section decreased abruptly at the onset of full spermatogenesis, and, as the tubules lengthened, the total number of these cells per testis remained constant. The number of A spermatogonia per cross section did not vary; consequently the total number per testis increased. The first spermatocytes appeared at 3-4 yr of age at a body weight of 3.24 +/- 0.15 kg, and full spermatogenesis was attained between 3 years, 8 months and 4 years, 4 months at a body weight of 3.5-3.8 kg. Plasma levels of androstenedione did not exhibit a clear pattern of variation, whereas plasma dihydrotestosterone and testosterone reached high levels with great fluctuations at the time full spermatogenesis was established. No relation between plasma testosterone level and the initiation of meiosis was observed.

Androgens↗
PubMed1983

Morphometry of fetal Leydig cells in the monkey (Macaca fascicularis), correlation with plasma testosterone.

The evolution of Leydig cells in Macaca fascicularis fetuses was followed throughout gestation (50-150 d) by morphometric procedures (volume densities of: cells, SER, mitochondria and lipid droplets). Testosterone from umbilical artery plasma was radioimmunoassayed starting on day 57. After predifferentiation and differentiation phases, Leydig cells entered the maturity phase (57-66 d), they occupied 19% of testicular volume, SER and lipid droplets represented 19% and 5% respectively of cytoplasmic volume. Then Leydig cells regressed dramatically (involution phase I: 66-83 d), their volume density decreased to 8%, that of SER to 12% whereas lipids doubled. Leydig cell volume density diminished to 5% during the second half of gestation (involution phase II), but their ultrastructure was not significantly altered. High plasma testosterone level (2.4 ng/ml) was observed during the maturity phase of Leydig cells, decline of testosterone occurred during involution phases I and II (1.13 and 0.58 ng/ml respectively). Its was shown that from day 57 to the end of fetal development the evolution of the plasma testosterone level correlated with the Leydig cell volume density and the SER volume density.

Animals↗
PubMed1982

Relationships between fat and plasma androstenone and plasma testosterone in fatty and lean young boars during growth and after hCG stimulation.

The effect of weight of fatty tissue on fat and plasma androstenone and on plasma testosterone relationships in the young boar was studied. For this purpose, hCG stimulation of steroid testicular production was performed in 12 boars and fat androstenone concentration subsequently measured. In addition plasma androstenone and testosterone were determined in 8 of them, previously cannulated. The results show that: 1) although plasma testosterone response to hCG stimulation was similar in all boars, fat and plasma androstenone responses were very variable between boars, 2) weight of fatty tissue appeared to have little influence, if any, on androstenone exchanges between plasma and fatty tissue and 3) plasma androstenone/testosterone ratio appeared to be less variable within boars than between boars. The data show that there is probably some between-boars-variability in the respective rates of elimination of testosterone and androstenone.

Adipose Tissue↗
PubMed1982

Relationships between fat and plasma androstenone and plasma testosterone in fatty and lean young boars following castration.

The effect of weight of fatty tissue on fat and plasma androstenone and on plasma testosterone relationships was studied in the young boar following castration. For this purpose, 9 boars were castrated at 175 days of age, plasma steroid levels were determined daily up to 10 days after orchidectomy and fat androstenone concentration was measured 1, 3, 6, 10 and 15 days after castration. The results show that the apparent half-life of stored androstenone is very variable between boars (range: 4 to 14 days) and do not depend on the weight of fatty tissue. The rate of elimination of plasma androstenone is also very variable between boars. The rate of disappearance of fat androstenone following castration does not depend on the rate of androstenone release from fatty tissue to peripheral plasma but is more likely dependent on the intensity of plasma androstenone catabolism and elimination. Therefore, fat androstenone concentration in the intact boar is almost only depending on the equilibrium between the respective rates of testicular production and elimination.

Adipose Tissue↗
PubMed1981

Annual plasma testosterone cycle and ejaculatory ability in the laboratory-housed crab-eating macaque (Macaca fascicularis).

Six fertile and healthy adult Macaca fascicularis males were studied. Radioimmunological assay of the plasma testosterone, sampled without anesthesia in the afternoon at the beginning of each month, showed an annual hormone cycle with a maximum (16.7 +/- 1.1 ng/ml) in the fall and a minimum (9.5 +/- 0.9 ng/ml) in the spring (fig. 1). Using the ratio: number of ejaculations/number of trials, the ejaculatory ability of these animals (fig. 2) was estimated for 10 min in the presence of females between days 12 and 15 of their menstrual cycle. This ability showed no cyclic variation during the year. Comparing the annual variation of testosterone levels in macaque males (Macaca mulatta, Macaca arctoides, Macaca nemestrina, Macaca fascicularis) and man, we found that, except for Macaca arctoides and Macaca nemestrina, the maximal simian levels always coincided with autumn and the minimal levels with spring in spite of the different rearing environments. (table 2). After studying ejaculatory ability and plasma testosterone level in the intact macaque throughout the year and comparing it to the results obtained by Resko and Phoenix (1972), Phoenix et al. (1973) and Michael and Wilson (1974, 1975) studying castrated males, we believe that above a minimal level, variation in the plasma testosterone level does not affect male sexual behavior, at least as far as ejaculatory ability is concerned. Moreover, during this study we noted that above a maximal plasma testosterone level, varying with the season, the ejaculation rate may be depressed (fig. 3).

Animals↗
PubMed1981

Changes in Leydig cells and luteinizing hormone receptors in porcine testis during postnatal development.

LH receptors have been characterized in porcine testis (Sus crofa L.) from birth to 220 days of age and have been related to interstitial tissue development (especially Leydig cells). The mean association constant (Ka) of ovine [3H]LH, was 7 +/- 6 X 10(9) M-1, with no apparent age-dependent variation but with some significant individual variations. The concentration of specific LH receptor sites reached a maximum of 9 X 10(-12) M/g testis between days 20-70, decreased to 3 X 10(-12) M/g testis at the onset of puberty (up to 100 days), and remained stable at the same level in the adult. The total number of sites per testis essentially reflected the growth of the testis. Interstitial tissue occupied up to 80% of the volume of the whole testis during the occupied up to 80% of the volume of the whole testis during the first 30 neonatal days. It decreased to about 25% after 120 days. The Leydig cells in this tissue occupied the same proportion (70% of the volume of the whole testis) regardless of the age of the animals. The mean Leydig cell diameter reached a maximum of 20 micrometer at 30 days of neonatal life, decreased to a minimum of 10 micrometer at 90 days, and then increased to a stable value of 15 micrometer after puberty. The number of Leydig cells per unit volume varied with age, with a maximum of 3 X 10(8) cells/ml testis at 90 days, reaching a constant value of 6 X 10(7) cells/ml testis after puberty. These data suggest that each Leydig cell contains 80,000 specific LH-binding sites/cell 30 days after birth and 35,000 in the adult, with no observed periods without receptor sites. The number of receptors per cell is correlated to cell size rather than stage of sexual maturation. (Endocrinology 108: 625, 1981)

Aging↗
PubMed1975

[Quantitative variations in the plasma testosterone in male pigs, from birth to adult].

Testosterone peripheral venous blood level in newborn piglet shows a large rise after birth with a maximum level between days 5 and 17. Except for a peak between days 35 and 45, values decrease regularly during the first six weeks, then stay low during the third month. From the fourth to the sixth month, testosterone level progressively increases (onset of puberty). After a larger rise between 180 and 200 days (period when sexual behavior begins), testosterone plasma level increases to reach adult values. According to these observations, the androgenic function in pig presents some analogy with man.

Age Factors↗