Light and electron microscopic studies of the acute and chronic toxic effects of N-nitroso compounds on the marine mussel, Mytilus edulis (L.). II. N-methyl-N-nitro-N-nitrosoguanidine

Circatidal variation in epithelial cell proliferation in the mussel digestive gland and stomach

“…This phenomenon, known as cell-type replacement (CTR), is clearly initiated after merely a few hours of environmental insult and constitutes a fully reversible process, with cell-type ratios returning to normal within a few days after the cessation of the stress (Marigómez et al 1998b). In early reports, CTR was believed to be caused by the enhanced proliferation of basophilic cells (Thompson et al 1974;Rasmussen et al 1983;Cajaraville et al 1990;Marigómez et al 1990Marigómez et al , 1998a. However, although the idea of the proliferation of basophilic cells cannot be totally discarded, recent experiments suggest that CTR rises because of digestive cell loss rather than by basophilic cell proliferation (Marigómez et al 1998b;Zaldibar et al 2001).…”

“…Indeed, the digestive epithelium has been proposed to be fully regenerated every feeding cycle, which lasts a few hours (Nelson and Morton 1979). Regardless of whether such rapid cell renewal occurs, diverse sources of environmental stress have been demonstrated to cause a reorganisation of the epithelium resulting in an increased proportion of basophilic cells (Thompson et al 1974;Rasmussen et al 1983;Cajaraville et al 1990;Marigómez et al 1990Marigómez et al , 1998aSyasina et al 1997). This phenomenon, known as cell-type replacement (CTR), is clearly initiated after merely a few hours of environmental insult and constitutes a fully reversible process, with cell-type ratios returning to normal within a few days after the cessation of the stress (Marigómez et al 1998b).…”

Responses of basophilic cells of the digestive gland of mussels to petroleum hydrocarbon exposure

“…Furthermore, quite distinct stress sources such as crowding of the larval stages of Schistosoma japonicum in the intertubular spaces of the digestive gland of the gastropod Oncomelania hupensis quadrasi resulted in a marked increase of pyramidal calcium cells (possibly equivalent to bivalve basophilic cells) together with vacuolation of digestive cells (Querubin & Enriquez 1989). This again seems to indicate that basophilic cells of molluscan digestive tissue respond to a variety of harmful conditions by increasing their numbers and that this response is usually associated with degenerative changes in digestive cells (Thompson et al 1974, Rasmussen et al 1983, Querubin & Enriquez 1989). Whether increased numbers of basophilic cells are simply due to concomitant reduction in digestive cell numbers or whether basophilic cell proliferation is a necessary step for digestive cell regeneration remains to be investigated.…”

“…Petroleun~ hydrocarbon exposure induces the accumulation of large quantities of lipids in basophilic cells of mussels together with the fragmentation and vacuolation of cisterns of the rough endoplasmic reticulum and Golgi bodies (Carles et al 1986, Lowe 1988. Further, Rasmussen et al (1983) note that 'chronic' treatment of mussels with a N-nitroso con~pound causes varying degrees of degeneration in cells comprising the digestive epithelium, and that some digestive tubules are only composed of basophilic cells exhibiting dilatation and condensation of the endoplasmic reticulum. Widdows et al (1984) found that exposure to petroleum hydrocarbons causes an 'apparent' increase in the numbers of basophilic cells in the prosobranch gastropod Littorina Littorea while they do not report similar changes in Mytilus edulis maintained under the same conditions.…”

Ultrastructural Changes in the Mantle of the Equilateral Venus, Gomphina veneriformis (Bivalvia: Veneridae) Exposed to TBTCl

“…특히, 동물의 생식관련 내분비계 장애를 유발시키고, 면역독성, 호르몬 분비 억제 및 먹이 섭이 율 저하 등의 문제를 야기 하는 것으로 알려져 있다 (Kannan et al, 1997;Gauthier-Clerc et al, 2002;Halldórsson et al, 2005). 또한 TBT가 기관계의 구조적 변화를 유도하여 기능적인 장애를 초래하였다는 사실 또한 여러 연구자들에 의 해서 보고되어 왔다 (Rasmussen et al, 1983;Hinch and Stephenson, 1987;Regoli and Orlando, 1994;Quinn et al, 2004).…”