A Seasonal Cycle in the Testis of the Spurdog, Squalus Acanthias, and the Sites of 3β-Hydroxysteroid Dehydrogenase Activity

Abstract

The histology of the spurdog (Squalus acanthias L.) testis was observed through a complete annual cycle. The maximum sperm accumulation coincided with the breeding time as defined by the biennial female cycle. Degeneration of spermatogonia was observed following breeding. The band of degenerate germinal ampullae was identical to that described as occurring in Scyliorhinus canicula (L.) following pituitary ventral lobectomy. This suggested a resting phase in the production of a specific pituitary gonadotrophin lasting for about four months. All spermatocytes were transformed to spermatozoa within 12 months. 3β-Hydroxysteroid dehydrogenase activity was located in semen, in Sertoli cell cytoplasm and in the lumens of mature germinal ampullae. A possible seasonal change in this activity due to the migration of the degenerate band is suggested. Interstitial cells of Leydig could not be observed.INTRODUCTIONThe Scottish-Norwegian stock of the spurdog, Squalus acanthias L., sampled for this study, was shown by Holden (1965) to make an autumn breeding migration from the region of the Orkney and Shetland isles to the breeding areas in the Minch off north-west Scotland. During January and February those females carrying embryos at the end of their second year of development move inshore and liberate their young in shallow water. At this time the ovaries of these fish contain from three to fifteen eggs ready for ovulation (Holden & Meadows, 1964), and observations suggest that copulation, ovulation and the commencement of a further pregnancy follow almost immediately. Following copulation, the spermatozoa must reach the oviducal gland at the head of the oviduct in order that the eggs may be fertilized before they are enclosed by the candle membranes.

Stage-dependency of apoptosis and the blood-testis barrier in the dogfish shark (Squalus acanthias): cadmium-induced changes as assessed by vital fluorescence techniques

“…that of the ZD, a finding that is consistent with the TUNEL analysis (McClusky 2005). The ZD, which is thus labelled by both the TUNEL and the AO techniques, represents the past winter's M-PrM cysts that ceased any further development (McClusky 2005), presumably as a result of a natural break in pituitary gonadotropin support during the winter months (Simpson and Wardle 1967;Dobson and Dodd 1977). AO-labelling varies from discrete punctate bright green labelling (in mid-stage PrM cysts), which indicates an early stage of germ cell apoptosis, to intense yellow-orange labelling observed in flattened ZD cysts, which indicates an advanced stage of apoptosis and labelling associated with the phagocytosed germ cell corpses in Sertoli cells.…”

Stage and season effects on cell cycle and apoptotic activities of germ cells and Sertoli cells during spermatogenesis in the spiny dogfish (Squalus acanthias)

“…Follow-up biochemical and in situ fluorescence analyses (McClusky et al 1996) to an initial report of Simpson & Wardle (1967), which described a zone comprising several layers of degenerating germinal tissue that first appears naturally in May in S. acanthias at the spermatogonia-spermatocyte transition, confirmed the mode of death in this tissue as apoptosis. Since it has always been assumed that the month of May also marked the onset of the spermatogenically active period in Squalus , Piferrer & Callard 1995, the observation of such a large stage-specific loss of testicular cells during presumed normal testicular recrudescence was indeed intriguing.…”

“…As summarized in Table 1, staging criteria were based on (a) position of the cyst in the testis cross-section relative to the germinal ridge (maturational order), (b) cyst diameter and (c) cyst organization with respect to relative numbers and positions of germ-cell versus Sertoli-cell nuclei, as Cell cycle and apoptosis in the shark testis 91 www.reproduction-online.org described in earlier studies of this and other dogfish species (Stanley 1966, Simpson & Wardle 1967, Holstein 1969. For example, based on actual cell counts per spermatocyst, Sertoli cells have been reported to undergo nine, and germ cells an additional four, mitotic divisions in Squalus (Holstein 1969).…”

Stage-dependent modulation of Sertoli cell steroid production in dogfish (Scyliorhinus canicula)

“…Histochemical data have shown that 3ß-hydroxysteroid dehydrogenase (3ß-HSD) activity is local¬ ized in the cytoplasm of the Sertoli cell of the dogfish (Simpson and Wardle, 1967;Collenot, 1969). Dubois and Callard (1989) have demonstrated 3ß-HSD, hydroxylase/lyase and aromatase activities in Sertoli cells of Squalus acanthias in vitro.…”