Library

X
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
    Muscle fiber types in women athletes and non-athletes (1977)
    Springer
    Pflügers Archiv 371 (1977), S. 161-165 
    Details
    ISSN: 1432-2013
    Keywords: Human muscle ; Fiber types ; Women ; Exercise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle biopsies were obtained from the vastus lateralis muscle of 5 female collegiate field hockey players and 5 untrained female students. The fibers were classified histochemically as fast-twitchoxidative-glycolytic (FOG), fast-twitch-glycolytic (FG) and slow-twitch-oxidative (SO). The fibers were found to be similar to those of males in distribution and histochemical properties, but were smaller. In the women athletes all 3 fiber types were larger than the respective fibers in the controls. Also, the athletes had a much higher percentage of oxidative fibers (SO+FOG), 83% vs. 46%. A direct relationship between fiber size and oxidative activity was observed in fasttwitch fibers, whereas the reverse was found in slowtwitch fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580785
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Human muscle fiber types in power lifters, distance runners and untrained subjects (1976)
    Springer
    Pflügers Archiv 363 (1976), S. 19-26 
    Details
    ISSN: 1432-2013
    Keywords: Human muscle ; Fiber types ; Exercise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Muscle biopsies were taken from the vastus lateralis of 12 males: 5 control subjects, 4 power lifters and 3 distance runners. Three fiber “types” were distinguished by comparing serial sections for alkaline myofibrillar adenosine triphosphatase (ATPase) and succinic dehydrogenase (SDH) activities: 1. high ATPase and low SDH; fast-twitch-glycolytic (FG). 2. High ATPase and high SDH; fast-twitch-oxidative-glycolytic (FOG). 3. Low ATPase and high SDH; slow-twitch-oxidative (SO). In some cases the distinction between the FOG and FG classes was not clear and a group termed “transitional” was employed. A variation in percentage of fiber types and fiber area was found among individuals. The percentage of SO fibers varied from 19.6–60.1% within all 3 groups, with a mean of 40.5%. In the control group approximately 75% of the fibers were oxidative (FOG+SO). The major characteristics of the lifters were a decrease in the percentage of FOG fibers and a hypertrophy of FOG and FG fibers. The distance runners had a high percentage of oxidative fibers with few FG fibers. It is suggested that the fast-twitch fibers are mainly involved in the adaptation of muscle to exercise since the percentage of SO fibers varies greatly among individuals within and between the 3 groups studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587397
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural evidence of indirect and direct autonomic innervation of human Leydig cells: comparison of neonatal, childhood and pubertal ages (1992)
    Springer
    Cell & tissue research 269 (1992), S. 383-390 
    Details
    ISSN: 1432-0878
    Keywords: Autonomic innervation ; Leydig cells ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Recent physiological studies have indicated an autonomic influence on the secretion of testosterone from Leydig cells in humans and laboratory animals. Furthermore, a few studies have shown enhanced autonomic control of Leydig cell function in immature, relative to mature, laboratory animals. In the current ultrastructural study of the human testicular interstitium the morphology of autonomic components is described from neonatal, childhood and pubertal ages. Autonomic nerve fibers and varicosities with neurotransmitter vesicles are described in proximity to Leydig cells. The observed autonomic terminals are classified by vesicle morphology into three general types: (1) Type I with predominately small agranular vesicles (30–60 nm) and occasional larger granular vesicles (100 nm). This type is morphologically consistent with being cholinergic. (2) Type II with predominately small granular vesicles (30–60 nm), as well as sporadic large granular vesicles. These are morphologically consistent with adrenergic terminals. (3) Type III which exhibit numerous large granular vesicles of mixed size. Evidence of autonomic terminals is encountered most frequently in childhood biopsies, age 3 to 10 years. The neonatal specimen (4 months) is noteworthy in that many of the Schwann cells appear immature and no adrenergic terminals are observed. In contrast, terminals morphologically consistent with being adrenergic are common in the childhood series of biopsies. Although the vast majority of the autonomic terminals are associated with Leydig cells indirectly as “boutons en passant”, separated by approximately 150 nm to more than a μm, evidence of direct contact (20 nm) of autonomic terminals with Leydig cells is presented. These findings provide morphological evidence of frequent indirect and rare direct contact of autonomic nerve terminals with Leydig cells in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353893
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructure of immature leydig cells in the human prepubertal testis (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 209 (1984), S. 165-176 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The cellularity of the human prepubertal testicular interstitium has not been well studied at the ultrastructural level. In this study, testicular biopsies were obtained from 35 boys aged three to nine years and examined by electron microscopy to clarify and quantitate the cell types present during the prepubertal period.The prepubertal testicular interstitium is found to consist of immature Leydig cells (9%), primitive fibroblastic cells (63%) (intertubular in location), and attenuated peritubular fibroblasts (28%). The primitive fibroblastic cells and peritubular fibroblasts appear closely related, being distinguished mainly by shape and location. The immature Leydig cell type contrasts with the fibroblastic cell types by exhibiting an irregular nucleus with relatively little heterochromatin. The most impressive cytoplasmic feature is the moderate to extensive development of smooth endoplasmic reticulum in the form of anastamosing tubules. In contrast, the rough endoplasmic reticulum is not well developed. Other cytoplasmic characteristics are the highly developed Golgi elements and occasional lipid droplets and lysosomes. Glycogen is also often present and is generally found in those cells that do not contain a welldeveloped smooth endoplasmic reticulum. The ultrastructure of the immature Leydig cell is compared with that of the mature fetal and adult Leydig cells. Although generally found in small clusters between tubules, these cells are often attenuated and closely associated with the seminiferous tubules. Occasional intermediate cell morphologies suggest a relationship between the primitive fibroblasts and immature Leydig cells.The presence of small cells exhibiting a steroid-producing morphology, classified as immature Leydig cells, in the prepubertal testicular interstitium is an interesting finding and is in accordance with earlier studies on nonhuman mammals. It is unknown whether these cells are remnants of the fetal Leydig cell population or have differentiated neonatally from the primitive fibroblastic cells. It is suggested that the immature Leydig cells are the progenitors of the adult Leydig cell population.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092090204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructural evidence of mature Leydig cells and Leydig cell regression in the neonatal human testis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 228 (1990), S. 405-417 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The neonatal period in male development is characterized by an acute rise in serum testosterone, which peaks at 2 to 3 months of age. The purpose of this study is to examine the neonatal human testicular interstitium at 4 months for evidence of Leydig cell maturation, as well as any morphological criteria relating to the fate of Leydig cells during this period, specifically, for signs of cell regression.Leydig cells are described with impressive development of the steroid secreting apparatus, which are consistent with the mature Leydig cells found during early fetal development and in the adult. The outstanding feature of these cells is the “organelle association” of extensive, anastamosing tubules of smooth endoplasmic reticulum (SER), pleomorphic mitochondria with a component of tubular cristae, and abundant microperoxisomes associated with the SER. Well-developed Golgi elements, regionalized RER, and diverse cell inclusions are also characteristics of these cells. Reinke crystals and paracrystalline inclusions are absent. Gap junctions are common in this system and are notable in the asymmetric nature of the adjacent cytoplasmic components.These findings provide a morphologic correlate to the reported neonatal phase of testosterone production in man.Intermediate forms of Leydig cells are described with “organelle associations” including decreased SER with increased lipid droplets, and decreased SER with prominent cytoplasmic filaments and/or dramatic mitochondrial changes supportive of mitochondrial involution. Cells consistent with immature Leydig cells are also present. The rather impressive diversity in cell morphology present during this time frame of 4 months, slightly past the peak in testosterone production, provides evidence of Leydig cell regression and a continuity of the mature neonatal Leydig cells with the immature Leydig cells of childhood (Prince, 1984). There is also some evidence of cell degeneration.Although the developmental history of Leydig cells has been described for years as biphasic, it is time to view Leydig cell development in man as a triphasic event, fetal, neonatal, and pubertal.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092280406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The ultrastructure of the medial preoptic area of the rat (1974)
    Springer
    Cell & tissue research 153 (1974), S. 517-530 
    Details
    ISSN: 1432-0878
    Keywords: Medial preoptic area ; Hypothalamus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neuronal and glial cell bodies and the neuropil of the medial preoptic area of the rat hypothalamus were studied under the electron microscope. Two different types of neurons are identified on the basis of electron density. These two types differed in a number of ultrastructural features. Three types of nerve terminals based on vesicle morphology are also described, as well as the general structure of the axons, dendrites and synapses in the neuropil. The structure of oligodendrocytes and astrocytes is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231544
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...