Aspects of spermatogenesis in immature and mature specimens of the long-lived Greenland shark: Novelties concerning the germinal compartment's assembly, complement of Sertoli cells and demise.

Cystic spermatogenesis in the subadult, maturing and adult Greenland shark (Somniosus microcephalus) displays multiple novel features, characterized early on by an unorganized internal cellular environment of the spermatocysts (anatomically discrete follicle-like units containing a single germ cell stage and its complement of co-developing Sertoli cells). These typically show polar asymmetries due to asymmetrically distributed germ and Sertoli cells. These arise from several novel cellular rearrangements at the immature pole, including fusion of a cluster of somatic cells with newly formed cysts containing only one to three spermatogonia and that already display an excess of Sertoli cells.

Several routes of cell death to secondary necrosis in the elasmobranch testis.

The process of spermatogenesis features significant germ cell loss through apoptosis. Routine histology of the testes of well-studied animal models hardly discloses any trace of their phagocytic clearance by the supporting Sertoli cells. This review highlights lessons learnt from the cystic, diametric testes of some seasonally migrating elasmobranchs (e.

Multiple Sources for Sertoli Cells and Two Sertoli Phenotypes in the Adult Elasmobranch Testis: Insight from Two Species Belonging to Different Orders.

Findings presented here for the chondrichthyans Prionace glauca and Isurus oxyrinchus show that the assembly of the spermatocyst and it's attached collecting duct are seamlessly connected developmental phenomena. The cyst's somatic cell component (i.e.

The challenges of primary health care nurse leaders in the wake of New Health Care Reform in Norway.

Background: The local municipality, whose management style is largely inspired by the New Public Management (NPM) model, has administrative responsibilities for primary health care in Norway. Those responsible for health care at the local level often find themselves torn between their professional responsibilities and the municipality's market-oriented funding system. The introduction of the new health care reform process known as the Coordination Reform in January 2012 prioritises primary health care while simultaneously promoting a more collaborative and multidisciplinary approach to health care.

A Comparative Study of Intratesticular Ductules in the Spermatogenically Active Testes of Shortfin Mako and Thresher Sharks.

This comparative study of the radial testes of sexually mature thresher sharks (Alopias vulpinus) and shortfin mako sharks (Isurus oxyrinchus) describes the histology of the three-tiered network of sperm-carrying ductules in the testis and the lymphomyeloid tissue associated with it, namely the epigonal organ. In both species, a testis → epigonal gradient was evident regarding the thickness of the ductule epithelial lining and subepithelial investment of connective tissue. Ductules straddling the testis-epigonal border often displayed luminal leukocytes and various signs of regression, including the progressive thickening of the ductule epithelial lining, dissolution of the cytoplasm, and loss of normal histoarchitecture.

Sperm of Galeorhinus galeus (Elasmobranchii, Triakidae) Traverse an Excurrent Duct System Characterized by Pronounced Regionalization: A Scanning Electron and Light Microscopy Study.

The transport and subsequent maturation of spermatozoa in the vertebrate excurrent duct require the creation of a series of biochemically defined luminal milieus along the length of the duct. Such specialization is accomplished, among others, by changes in the epididymal histoarchitecture. Here we show that the intratesticular and extratesticular genital ducts of mating Galeorhinus galeus exhibit pronounced regionalization both in terms of epithelial histology and lumen diameter size.

The epigonal organ and mature pole of the testis in the recreationally fished blue shark (Prionace glauca): histochemico-functional correlates.

The exact role of the immune system in normal spermatogenesis is poorly understood. The attachment, however, of the lymphomyeloid epigonal organ specifically to the testis's mature pole in many shark species is a curious finding. Unlike the histology of the lymphomyeloid tissues of many other elasmobranchs, the epigonal organ leukocytes of wild-caught blue shark (Prionace glauca), besides exhibiting extensive nuclear heterogeneity, contain some of the largest known granules ever seen in vertebrate white blood cells.

Coordination of spermatogenic processes in the testis: lessons from cystic spermatogenesis.

A common observation in the vertebrate testis is that new germ cell clones enter spermatogenesis proper before previously formed clones have completed their development. The extent to which the developmental advance of any given germ cell clone in any phase of spermatogenesis is dependent on that of neighboring clones and/or on the coordinating influence of associated Sertoli cells in the immediate vicinity or of others further away remains unclear. This review presents an overall synthesis of findings in an ancient vertebrate, the spiny dogfish shark and shows that, even at this phyletic level, the developmental advance of a given germ cell clone is the outcome of various processes emanating from its spatiotemporal relationship with (1) its own complement of Sertoli cells in the anatomically distinct spermatocyst and (2) Sertoli cells associated with other germ cell clones that lie upstream or downstream in the spermatogenic progression and that secrete, among others, androgen and estrogen destined for target sites upstream.

On making nursing undergraduate human reproductive physiology content meaningful and relevant: discussion of human pleasure in its biological context.

The traditional presentation of the Reproductive Physiology component in an Anatomy and Physiology course to nursing undergraduates focuses on the broad aspects of hormonal regulation of reproduction and gonadal anatomy, with the role of the higher centres of the brain omitted. An introductory discussion is proposed which could precede the lectures on the reproductive organs. The discussion gives an overview of the biological significance of human pleasure, the involvement of the neurotransmitter dopamine, and the role of pleasure in the survival of the individual and even species.

Fetal bovine serum simultaneously stimulates apoptosis and DNA synthesis in premeiotic stages of spermatogenesis in spiny dogfish (Squalus acanthias) in vitro: modulation by androgen and spermatogenic activity status.

Using the simple cystic spermatogenesis in the shark testis as a model, we previously reported the relative resistance of immature spermatogonia (stem cell and early-stage spermatogonia) to apoptosis in the normal testis and after spermatoxicant exposure in vivo. Apoptosis was monitored by fluorescence image analysis of living cysts, using the validated acridine orange (AO) vital staining technique. Findings show that FBS simultaneously stimulates both apoptosis and [(3)H]thymidine incorporation in immature spermatogonial clones in a concentration-dependent manner in vitro.