Alterations of the eyes during ontogenesis inAporrhais pespelecani (Mollusca, Caenogastropoda)
- 37 Downloads
The cerebrally innervated eyes of metamorphically competent larvae, newly metamorphosed larvae, and adults ofAporrhais pespelecani are ultrastructurally investigated and compared. The eyes are composed of a lens, a cornea, and an everse retina. In adults, a humour is located behind the lens. The retina consists of two different types of cells: sensory cells and supportive cells. The present study confirms earlier results and demonstrates that the distal part of the sensory cells is altered during ontogenesis. In metamorphically competent larvae, the sensory cells are exclusively ciliary. In newly metamorphosed larvae and in adults, however, the sensory cells are of the mixed type, bearing both cilia and microvilli. Furthermore, the findings confirm that both the supportive and corneal cells, as well as the distal supportive cell processes which are restricted to the eyes of adults are involved in lens formation.
supportive cell process
Unable to display preview. Download preview PDF.
- Bartolomaeus T (1992) Ultrastructure of the photoreceptor in the larvae ofLepidochiton cinerus (Mollusca, Polyplacophora) andLacuna divaricata (Mollusca, Gastropoda). Microfauna Mar 7:215–236Google Scholar
- Crowther RJ, Bonar DB (1980) Photoreceptor ontogeny and differentiation inIlyanassa obsoleta. Am Zool 20:886Google Scholar
- Eakin RM, Brandenburger JL (1967b) Light-induced ultrastructural changes in the eyes of pulmonate snail,Helix aspersa. J. Ultrastruct Res 21:164Google Scholar
- Eakin RM, Brandenburger JL (1975) Understanding a snail’s eye at a snail’s pace. Am Zool 15:851–863Google Scholar
- Fretter V, Graham A (1962) British prosobranch molluscs Ray Society London, pp 449–476Google Scholar
- Mayes M, Hermans C (1973) Fine structure of the eye of the prosobranch molluscLittorina scutulata. Veliger 16:166–169Google Scholar
- Salvini-Plawen L (1980) Was ist eine Trochophora? Eine Analyse der Larventypen mariner Protostomier. Zool Jb Anat 103:389–423Google Scholar
- Salvini-Plawen L (1982) On the polyphyletic origin of photoreceptors In: Westfall J (ed) Visual cells in evolution. Raven Press, New York, pp 137–154Google Scholar
- Scheltema R (1989) Planktonic and non-planktonic development among prosobranch gastropods and its relationship to the geographic range of species. In: Ryland J, Tyler P (eds) Reproduction, genetics and distribution of marine organisms. 23rd European Marine Biology Symposium. Olsen and Olsen, Fre-131densborg, Denmark, pp 183–188Google Scholar
- Strathmann MF (1987) General procedures. In: Strathmann MF (ed) Reproduction and development of marine invertebrates of the northern Pacific coast. University of Washington Press, Seattle, pp 3–44Google Scholar