Testicular Weight, Sertoli Cell Number, Daily Sperm Production, and Sperm Output of Sexually Mature Rabbits after Neonatal or Prepubertal Hemicastration1

Thompson, Terry L.; Berndtson, W. E.

doi:10.1095/biolreprod48.5.952

Cited by 26 publications

(19 citation statements)

References 35 publications

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“…Rabbits are sexually mature at the oldest ages studied by Bredman et al [1992a], but they continue to grow and testis weight continues to increase until the age of 6 months [Thompson and Berndtson, 1993]. In their studies of earlier developing animals, Bredman et al [1992a] have shown that some isoforms of MyHCs are transiently expressed during development, and that there seems to be a trend toward more fibers expressing cardiac alpha MyHC at older ages.…”

Section: Discussionmentioning

confidence: 99%

“…However, the largest animals studied (body weight 2,000 g, approximate age = 2 months) must be considered immature. Rabbits no longer express developmental MyHC isoforms at this age, but they continue to grow until they are at least 6 months old [Thompson and Berndtson, 1993], and their MyHC isoform content may change during this period [d'Albis et al, 1993]. Whether or not the same heterogeneity of phenotypes is found in fully mature rabbits is not known.…”

Section: Abbreviations Used In This Papermentioning

confidence: 99%

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Sexual Dimorphism in the Rabbit Masseter Muscle: Myosin Heavy Chain Composition of Neuromuscular Compartments

English

Eason²,

Schwartz³

et al. 1999

Cells Tissues Organs

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The myosin heavy chain (MyHC) isoform composition of six adult (>7 months old) male and female rabbit masseter muscles was studied using seven monoclonal antibodies. In matched serial tissue sections, muscle fibers in 10 different neuromuscular compartments were analyzed. Nearly all fibers were found to express one of five phenotypes. They either contained one of four different slow/beta MyHC phenotypes (I₁–I₄), nearly all of which co-express cardiac alpha MyHC, or they contained type IIa MyHC. Very few fibers contained slow/beta or cardiac alpha MyHC only or both the alpha/slow/beta and IIa isoforms. Most, but not all, of the compartments studied contained similar proportions of fibers of the five major phenotypes, at least within sex. For 7 of the 10 compartments studied, significant sex differences in the proportion of I₁ and IIa fibers were found. Males contained more IIa fibers and fewer I₁ fibers than females. Fibers of the IIa phenotype were significantly larger than fibers of all of the other phenotypes and larger in males than females.

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Section: Discussionmentioning

confidence: 99%

Section: Abbreviations Used In This Papermentioning

confidence: 99%

Sexual Dimorphism in the Rabbit Masseter Muscle: Myosin Heavy Chain Composition of Neuromuscular Compartments

English

Eason²,

Schwartz³

et al. 1999

Cells Tissues Organs

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“…Seven males and six females, all at least 6 months old, were used. Rabbits are sexually mature at 2 months old, but they continue to grow until they are 6 months old [Thompson and Berndtson, 1993]. All experiments were in accordance with NIH guidelines and the Institutional Animal Care and Use Committee of Emory University approved protocols for them.…”

Section: Methodsmentioning

confidence: 99%

Sex Differences in Rabbit Masseter Muscle Function

English

Widmer

2003

Cells Tissues Organs

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The proportions of fibers of different phenotypes in the rabbit masseter muscle differ strikingly in adult males and females. Muscles from females contain similar proportions of small fibers that express both the slow/β and cardiac α myosin heavy chain (MyHC) isoforms and larger fibers containing the IIa MyHC isoform. In muscles from males, nearly 80% of fibers are of the IIa phenotype. To evaluate the functional significance of these sex differences, we used finely graded intramuscular microstimulation to study the contractile properties of masseter motor units in >6-month-old male and female rabbits. Twitch forces and torques in males were significantly greater in magnitude than those of females. Greater proportions of units that produced larger forces/torques were encountered in the males. The same motor units produced force or torque more rapidly in males than in females, principally because units in which twitch rise times were >22 ms were found only in females. The forces applied to the mandible and the torques generated about the right mandibular condyle were studied during cortically evoked rhythmic activation of the masticatory muscles. The overall range of torque rise times and the magnitudes of the peak torques did not differ between sexes. The mean rise time was significantly shorter and the mean peak torque was significantly greater in males. We conclude that sex differences in fiber phenotype proportions are reflected in sex differences in motor unit properties and in the function of these motor units during rhythmic activation.

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“…Numbers of Sertoli cells in the seminiferous epithelia of knockout mice remain normal Given that testis size correlates with germ cell numbers, germ cell number depends on the number of Sertoli cells (Berndtson et al, 1987;Berndtson and Thompson, 1990;Thompson and Berndtson, 1993), and testicular enlargement can be accompanied by increased numbers of Sertoli cells (Hess et al, 1993), we next sought to determine whether Sertoli cell numbers were altered in Rbpj Fig. S8), but the overall number of Sertoli cells was not significantly different from that in the littermate control testes (Fig.…”

Section: Inactivation Of Rbpj In Sertoli Cells By Cell-specific Gene mentioning

confidence: 99%

RBPJ in mouse Sertoli cells is required for proper regulation of the testis stem cell niche

et al. 2014

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Stem cells are influenced by their surrounding microenvironment, or niche. In the testis, Sertoli cells are the key niche cells directing the population size and differentiation fate of spermatogonial stem cells (SSCs). Failure to properly regulate SSCs leads to infertility or germ cell hyperplasia. Several Sertoli cell-expressed genes, such as Gdnf and Cyp26b1, have been identified as being indispensable for the proper maintenance of SSCs in their niche, but the pathways that modulate their expression have not been identified. Although we have recently found that constitutively activating NOTCH signaling in Sertoli cells leads to premature differentiation of all prospermatogonia and sterility, suggesting that there is a crucial role for this pathway in the testis stem cell niche, a true physiological function of NOTCH signaling in Sertoli cells has not been demonstrated. To this end, we conditionally ablated recombination signal binding protein for immunoglobulin kappa J region (Rbpj), a crucial mediator of NOTCH signaling, in Sertoli cells using Amh-cre. Rbpj knockout mice had: significantly increased testis sizes; increased expression of niche factors, such as Gdnf and Cyp26b1; significant increases in the number of pre-and post-meiotic germ cells, including SSCs; and, in a significant proportion of mice, testicular failure and atrophy with tubule lithiasis, possibly due to these unsustainable increases in the number of germ cells. We also identified germ cells as the NOTCH ligand-expressing cells. We conclude that NOTCH signaling in Sertoli cells is required for proper regulation of the testis stem cell niche and is a potential feedback mechanism, based on germ cell input, that governs the expression of factors that control SSC proliferation and differentiation.

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Testicular Weight, Sertoli Cell Number, Daily Sperm Production, and Sperm Output of Sexually Mature Rabbits after Neonatal or Prepubertal Hemicastration1

Cited by 26 publications

References 35 publications

Sexual Dimorphism in the Rabbit Masseter Muscle: Myosin Heavy Chain Composition of Neuromuscular Compartments

Sexual Dimorphism in the Rabbit Masseter Muscle: Myosin Heavy Chain Composition of Neuromuscular Compartments

Sex Differences in Rabbit Masseter Muscle Function

RBPJ in mouse Sertoli cells is required for proper regulation of the testis stem cell niche

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