Radulaersatz und Zellproliferation in der r�ntgenbestrahlten Radulascheide der NacktschneckeLimax flavus L. Ergebnisse zur Arbeitsteilung der Scheidengewebe

Abstract

Head-shielded snails were irradiation with 50 000 R for controls. No effects of the body irradiation were found in the radula or in the radular gland epithelia. 5. Division of labour in the radular gland. The temporary elimination of the superior epithelium and the epithelial region above the odontoblasts-groups does not affect the tooth-formation and the radula transport into the oral cavity. Hence it follows: a) The odontoblasts-group is exclusively responsible for the definitive shape of the tooth (Fig. 8 and 9). b) The radula is transported into the oral cavity by the inferior epithelium (cf. Chap. E, II, b). On account of these results it is possible for the first time to described comprehensively the division of labour in the radular gland (cf. Chap. E, V). 6. Development of abnormal radular gland epithelia. After irradiation with 50 000 R an abnormal epithelial system develops from the 2nd week on in the tip of the radular gland (Fig. 10a, b;aEep). It encloses sphaeric or tube-like cavities. In many cases they communicate with the lumen of the radular gland. The light-microscopic appearence of the cells of this abnormal epithelium resembles those at the tip of a non-irradiated radular gland (Fig. 11 a, b).

Novel Genes, Ancient Genes, and Gene Co-Option Contributed to the Genetic Basis of the Radula, a Molluscan Innovation

“…The radula develops as a ventral outpocketing of the foregut ( Page 2002 ; Page and Hookham 2017 ) and is usually made up of numerous rows of teeth, which are situated on a cuticular ribbon, the radular membrane ( Runham 1963 ; Kerth 1973 ; Wiesel and Peters 1978 ; Mackenstedt and Märkel 1987) . Since the radula is worn down anteriorly, it is continuously produced by the odontoblast cell group, which is situated at the caudal end of the radular sack ( Runham 1963 ; Kerth 1973 ; Wiesel and Peters 1978 ; Mackenstedt and Märkel 1987) . Coordinated cyclical secretion of tooth matrix by groups of odontoblasts defines size and shape of the developing teeth ( Kerth 1973 ; Mackenstedt and Märkel 1987) .…”

“…Since the radula is worn down anteriorly, it is continuously produced by the odontoblast cell group, which is situated at the caudal end of the radular sack ( Runham 1963 ; Kerth 1973 ; Wiesel and Peters 1978 ; Mackenstedt and Märkel 1987) . Coordinated cyclical secretion of tooth matrix by groups of odontoblasts defines size and shape of the developing teeth ( Kerth 1973 ; Mackenstedt and Märkel 1987) . The tooth matrix mainly consists of densely packed chitin fibers and so far unexplored nonchitinous macromolecules ( Peters 1972 ; Sone et al.…”

Original molluscan radula: Comparisons among Aplacophora, Polyplacophora, Gastropoda, and the Cambrian fossil Wiwaxia corrugata

“…This process of radular formation has produced great variation and complexity in form and function (e.g., Hickman, 1984). Radular formation and organogenesis have been studied by Schnabel (1903), Runham (1961Runham ( , 1963aRunham ( ,b, 1966, Isarankura and Runham (1968), Kerth and Krause (1969), Kerth (1971Kerth ( , 1973Kerth ( , 1976Kerth ( , 1979aKerth ( ,b, 1981Kerth ( , 1983a, Sirenko and Minichev (1975), Kerth and Hä nsch (1977), Wiesel and Peters (1978), Peters (1978Peters ( , 1979, Kerth et al (1981), Mischor and Mä rkel (1984), Mackenstedt and Mä rkel (1987), Eernisse and Kerth (1988), Warén (1990), Wolter (1992), Guralnick and de Maintenon (1997), Padilla (1998), and Guralnick and Lindberg (1999).…”

The rhipidoglossan radula: Radular morphology and formation in Nerita litterata Gmelin, 1791 (Neritimorpha, Neritidae)

“…Odontoblasts are grouping correspondingly to the number of teeth probably in all groups of gastropods. The number of odontoblasts forming one tooth has a phylogenetic signal: multicellular teeth formation found in patellogastropods (Peters, 1979;, few cells (and even unicellular tooth formation) is characteristic for Heterobranchia (Kerth, 1973(Kerth, , 1979Mackenstedt & Märkel, 1987;Vortsepneva, 2020). In Vetigastropoda (for the teeth of the central field)…”

“…Previous morphological studies of the radula have identified varying structural patterns in the tooth formation zone associated with different gastropod groups (Kerth, 1973(Kerth, , 1979Kerth & Krause, 1969;Mackenstedt & Märkel, 1987;Mikhlina et al, 2018;Mischor & Märkel, 1984;Peters, 1979;Vortsepneva, 2020;Vortsepneva et al, 2020;Wiesel & Peters, 1978). In the formation zone of the vetigastropod radula, the following characters were identified: (1) the blind end of the radular sac is separated by connective tissue structure into two horns where the marginal teeth are formed; odontoblasts of the marginal teeth form a multilayered epithelium arranged along with the teeth;…”