Staging equine seminiferous tubules by Nomarski optics in unstained histologic sections and in tubules mounted <i>in toto</i> to reveal the spermatogenic wave

Johnson, Larry; Hardy, Vince; Martin, Michael T.

doi:10.1002/ar.1092270205

Cited by 23 publications

(13 citation statements)

References 37 publications

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“…Daily sperm production is positively correlated with the number of Leydig cells (r = 0.76) in the horse (Johnson and Thompson, 1986) and the amount of Leydig cell smooth endoplasmic reticulum in humans ( Fig. 19; Johnson et al, 1990~).…”

Section: Leydig Cell Number and Organelle Contentmentioning

confidence: 98%

Efficiency of spermatogenesis

Johnson

1995

Microscopy Res & Technique

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Spermatogenesis is a process of division and differentiation by which spermatozoa are produced in seminiferous tubules. A measure of efficiency of spermatogenesis is the estimated number of spermatozoa produced per day per gram of testicular parenchyma. This measure is not influenced by species differences in testicular size; however, it is influenced by species differences in the numerical density of germ cells and in the life spans of these cells. Seminiferous tubules are composed of somatic cells (myoid cells and Sertoli cells), and germ cells (spermatogonia, spermatocytes, and spermatids). Activity of these three germ cells divide spermatogenesis into spermatocytogenesis, meiosis, and spermiogenesis, respectively. Spermatocytegenesis involves mitotic cell division to increase the yield of spermatogenesis and to produce stem cells and primary spermatocytes. Meiosis involves duplication and exchange of genetic material and two cell divisions that reduce the chromosome number and yield four spermatids. Spermiogenesis is the differentiation of spherical spermatids into mature spermatids which are released at the luminal free surface as spermatozoa. The spermatogenic cycle is superimposed on the three major divisions of spermatogenesis. Spermatogenesis and germ cell degeneration can be quantified from numbers of germ cells in various steps of development throughout spermatogenesis, and quantitative measures are related to number of spermatozoa in the ejaculate. Germ cell degeneration occurs throughout spermatogenesis; however, the greatest impact occurs during spermatocytogenesis and meiosis. Efficiency of spermatogenesis is related to the amount of germ cell degeneration, pubertal development, season of the year, and aging of humans and animals. Number of Sertoli cells and amount of smooth endoplasmic reticulum of Leydig cells (but not Leydig cell number) are related to efficiency of spermatogenesis. In humans, efficiency of spermatogenesis is reflected in number of spermatogenic stages per cross-section and number of missing generations within each stage; however, the arrangement of stages along the tubular length does not reflect differences in the efficiency of spermatogenesis. In short, spermatogenesis involves both mitotic and meiotic cell divisions and an unsurpassed example of cell differentiation in the production of the spermatozoon, and daily sperm production per g parenchyma is a measure of its efficiency.

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Section: Leydig Cell Number and Organelle Contentmentioning

confidence: 98%

Efficiency of spermatogenesis

Johnson

1995

Microscopy Res & Technique

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“…In the horse, as in other mammals, each tubular cross-section normally contains only one stage of the spermatogenic cycle. Consequently in the stage where sperm is released from the epithelium (stage I in the horse), no elongated spermatids can be detected (Johnson et al, 1990). In this case the Johnson score would be 7 for a normal tubule.…”

Section: Histological Evaluationmentioning

confidence: 99%

Effects of GnRH immunization in sexually mature pony stallions

Turkstra

Meer

Knaap³

et al. 2005

Animal Reproduction Science

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Immunization against gonadotrophin releasing hormone (GnRH) was studied as an alternative for the commonly used surgical castration in stallions. Two GnRH vaccines comprising non-mineral oil adjuvants were evaluated for their potential to induce high antibody titers directed against GnRH and subsequent effects on reproductive characteristics. Twelve sexually mature male hemicastrated Shetland ponies were assigned to three groups. Group 1 and 2 were injected with 1 mg peptide equivalent of G6k-GnRH-tandem-dimer conjugated to ovalbumin (OVA) in CoVaccine TM HT adjuvant (GnRH/CoVaccine) and in Carbopol (GnRH/Carbopol), respectively, and group 3 was injected with CoVaccine TM HT adjuvant without antigen (controls).After immunization no adverse effects were observed with respect to the injections sites or general health. Two weeks after the second vaccination antibody titers against GnRH increased rapidly in all animals of the GnRH/CoVaccine group, at the same time reducing serum testosterone levels maximally for the further duration of the experiment. In the GnRH/Carbopol group antibody responses and effects on testosterone levels were intermediate in two stallions and not apparent in the remaining stallions of this group. * Corresponding author. Tel.: +31 320 237212; fax: +31 320 238120.E-mail address: j.turkstra@pepscan.nl (J.A. Turkstra). J.A. Turkstra et al. / Animal Reproduction Science 86 (2005) 247-259Semen evaluation showed that from 2 weeks after the second immunization onwards, sperm motility was affected in all stallions treated with GnRH/CoVaccine and one stallion treated with GnRH/Carbopol. Seven weeks after the second immunization, no semen could be collected from two stallions, one of each group, due to suppressed libido. Histological examination of the testes, 15 weeks after the initial immunization, demonstrated reduction in seminiferous tubuli diameters in all stallions of the GnRH/CoVaccine group and one stallion of the GnRH/Carbopol group. Furthermore, spermatogenesis was extremely disorganized in these stallions, as indicated by absence of the lumen in the seminiferous tubules, the absence of spermatozoa and spermatids in the tubular cross-sections and the impossibility to determine the stage of the tubular cross-sections. Testis size was also substantially reduced in three out of four stallions treated with GnRH/CoVaccine.The results demonstrate that two immunizations with G6k-GnRH-tandem-dimer-OVA conjugate in a suitable adjuvant such as CoVaccine TM HT caused a rapid and complete reduction of serum testosterone levels in sexually mature stallions, subsequently leading to reduced sperm motility and affected testis function, while no adverse reactions were observed after immunizations.

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“…1974;Johnson et al 1990). This allows observation of more than one spermatogenic stage in a transverse section.…”

Section: Discussionmentioning

confidence: 99%

Immunolocalization of Aromatase in Stallion Leydig Cells and Seminiferous Tubules

Sipahutar

Sourdaine

Moslemi

et al. 2003

J Histochem Cytochem.

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S U M M A R Y High levels of plasma estrogens constitute an endocrine peculiarity of the adult stallion. This is mostly due to testicular cytochrome P450 aromatase, the only irreversible enzyme responsible for the bioconversion of androgens into estrogens. To identify more precisely the testicular aromatase synthesis sites in the stallion, testes from nine horses (2-5 years) were obtained during winter or spring. Paraplast-embedded sections were processed using rabbit anti-equine aromatase, followed by biotinylated goat antirabbit antibodies, and amplified with a streptavidin-peroxidase complex. Immunoreactivity was detected with diaminobenzidine. Immunofluorescence detection, using fluoroisothiocyanate-conjugated goat anti-rabbit antibodies, was also applied. Specific aromatase immunoreactivity was observed intensely in Leydig cells but also for the first time, to a lesser extent, in the cytoplasm surrounding germ cells at the junction with Sertoli cells. Interestingly, the immunoreactivity in Sertoli cells appears to vary with the spermatogenic stages in the basal compartment (with spermatogonia) as well as in the adluminal one (with spermatids). Relative staining intensity in Leydig and Sertoli cells and testicular microsomal aromatase activity increased with age. The present study in stallions indicates that in addition to Leydig cells, Sertoli cells also appear to participate in estrogen synthesis, and this could play a paracrine role in the regulation of spermatogenesis.

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Staging equine seminiferous tubules by Nomarski optics in unstained histologic sections and in tubules mounted in toto to reveal the spermatogenic wave

Cited by 23 publications

References 37 publications

Efficiency of spermatogenesis

Efficiency of spermatogenesis

Effects of GnRH immunization in sexually mature pony stallions

Immunolocalization of Aromatase in Stallion Leydig Cells and Seminiferous Tubules

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