GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 42 (1995), S. 149-158 
    ISSN: 1573-0867
    Keywords: Micrometeorology ; N flux ; livestock waste ; NH3 ; 15N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Gaseous ammonia (NH3) transport is an important pathway in the terrestrial N cycle. In the atmosphere NH3 neutralizes airborne acids and is a major factor determining air quality and acid rain deposition patterns. Redeposition of atmospheric NH3 plays an important role in the N balance of natural ecosystems and has been implicated in forest decline, plant species change and eutrophication of surface water. Much of the N in soil-plant animal systems can be lost to the atmosphere, particularly with surface applied livestock waste, or urea and anhydrous ammonia fertilizers. Plants can have a significant impact on NH3 transport because they can both absorb and desorb atmospheric NH3. Under conditions of low soil N or high atmospheric NH3 concentrations, plants absorb NH3. Under conditions of high soil N or low atmospheric NH3 concentrations, plants volatilize NH3. This article discusses methods for evaluating NH3 transport in the filed, the rate of NH3 volatilized from fertilizer application, and the effects of plants on net NH3 transport.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 239 (1985), S. 405-415 
    ISSN: 1432-0878
    Keywords: Testis ; Leydig cell ; FSH ; Morphometry ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of FSH on the testicular interstitial tissue of immature hypophysectomized rats were studied by comparing morphological changes in Leydig cells with quantitative changes in interstitial tissue histology using morphometric analysis. Three groups of rats received subcutaneous injections of 0.5 ml saline vehicle or 10 μg rFSH or 20 ng oLH (equivalent to the amount of LH known to contaminate the FSH), twice daily for 7 days. Administration of FSH significantly increased testis weight and stimulated more advanced spermatogenesis compared to saline or LH. Morphometric analysis of testes of LH-treated rats showed a small but significant increase in total interstitial cell volume compared to saline treatment. FSH caused much greater increases in the total volume of interstitial tissue and interstitial cells than either saline or LH and significantly increased the total volume of interstitial fluid by comparison with the other groups. FSH but not saline or LH treatment resulted in a striking hypertrophy of Leydig cells, to produce cells ultrastructurally identical to Leydig cells from adults. Since the target tissue of FSH is the seminiferous epithelium, the observed effects on Leydig cells by FSH treatment suggest that the secretion of factors by the seminiferous tubules may mediate the maturation of Leydig cells.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 243 (1986), S. 337-344 
    ISSN: 1432-0878
    Keywords: Macrophages ; Leydig cells ; Testis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Macrophages were identified in the intertubular tissue of the rat testis by loading animals with a particulate vital dye (trypan blue or India ink) and by localizing immunocytochemically a macrophage membrane antigen (MRC W3/25). Leydig cells were identified by the histochemical staining reaction for 3β-hydroxysteroid dehydrogenase activity and by a monoclonal antibody. Macrophages were scattered in the interstitial tissue closely attached to and mixed with the Leydig cells. They were never found in the seminiferous tubules. The macrophages comprised about 25% of all the cells in the interstitium. Double staining with a vital dye and a marker antibody showed that all the phagocytosing cells were macrophages and that the Leydig cells did not take up vital dyes. Double staining for the demonstration of the 3β-hydroxysteroid dehydrogenase activity and the macrophage antigen likewise revealed two distinctly different cell populations. Crude Leydig cell preparations obtained by collagenase treatment of the testis contained macrophages (12–14%). Macrophages were present throughout the postnatal prepuberal development of the testis. Their density was increased in the cryptorchid and irradiated testis.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 249 (1987), S. 367-377 
    ISSN: 1432-0878
    Keywords: Ethane dimethanesulphonate ; Leydig cells ; Destruction ; Regeneration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ethane dimethanesulphonate (EDS) was used as a specific cytotoxin to eliminate the Leydig cell population of the adult rat testis. Ultrastructural, morphometric and serum gonadotrophin and testosterone analysis was used to study the response of the intertubular tissue of the testis from 1 day to 10 weeks after EDS treatment. In control animals, the testis contained approximately 28 million Leydig cells and 8 million macrophages. Three to seven days after EDS treatment, Leydig cells were absent and serum testosterone was undetectable. Macrophage numbers increased three-fold by 3 days and returned to pretreatment values thereafter. At 2 and 3 weeks post-EDS, foetal-type Leydig cells (∼1–2 million per testis) appeared in proximity to perivascular and peritubular tissues, a feature also observed at 4 weeks when numerous such cells (∼15 million per testis) formed prominent clusters in perivascular and peritubular locations. Between 6 and 10 weeks after EDS treatment, the foetal-type Leydig cells were transformed morphologically into adult-type Leydig cells, they occupied central intertubular positions and their numbers were restored to pretreatment values. Regeneration of Leydig cells was reflected by elevated serum testosterone levels which returned towards the normal range. The results demonstrate the regenerative capacity of the testicular intertubular tissue and indicate a dual site of origin of Leydig cells which initially resemble foetal-type Leydig cells prior to establishing the adult-type Leydig cell population. The morphological pattern of Leydig cell regeneration suggests that in addition to gonadotrophic stimulation, local testicular factors from the seminiferous tubules may stimulate Leydig cell growth.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0003-276X
    Keywords: Spermatogenesis ; Testosterone ; Germ cell degeneration ; Testis ; Rat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Rapid and complete withdrawal of intratesticular testosterone was achieved via the destruction of all Leydig cells with the specific Leydig cell cytotoxin ethane dimethanesulphonate (EDS). Restoration of testosterone levels was accomplished by administration of a single dose (25 mg) of testosterone esters (T) known to reverse the antispermatogenic effects of androgen withdrawal. Quantitation of the degenerating germ cells in cross sections of seminiferous tubules (ST) at stages IV-V, VII, IX, and X-XI of the spermatogenic cycle was used as a sensitive biological index of the effects of testosterone withdrawal and restoration upon the function of the Sertoli cells. Compared to control testicular tissues, the mean numbers of pyknotic germ cells per ST cross section at stages VII, IX and X-XI increased significantly (P 〈 0.01-0.001) between 4 to 8 days post-EDS treatment, but only in stage VII tubules was this trend reversed significantly (P 〈 0.005) within 2 days by T supplementation. In EDS-treated rats, stages VII, VIII, IX, and X-XI also exhibited significant (P 〈 0.05-0.001) increases (compared to controls) in the volumetric proportions by which intraepithelial vacuoles appeared within the seminiferous tubules. Again, in EDS+T supplemented rats, the appearance of vacuoles was significantly (P 〈 0.001) suppressed in stage VII and VIII. In contrast to tubules at stages VII-XI, those at stages IV-V were completely unaffected by testosterone withdrawal or replacement. The results show that at selected time intervals after EDS treatment, testosterone supplementation is capable of preventing/reversing these morphological changes within 2 days in stage VII tubules. It is suggested that the induction and subsequent prevention of seminiferous epithelial damage will serve as an important in vivo and in vitro approach for studies on the androgen-mediated changes in Sertoli cell biology during phases of impairment and recovery of their function. Manipulation of adult Sertoli cell function as provided by our model should permit identification of androgen-regulated gene products together with an understanding of their role(s) in normal and abnormal spermatogenesis. © 1993 Wiley-Liss, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...