Morphogenesis in the Heterotrich Ciliate Climacostomum virens. II. Oral Development During Regeneration¹

Abstract

The regeneration (RG) of the oral apparatus (OA) by Climacostomum virens (Ciliophora, Heterotrichida) is examined by estimation of the ability of live cells to ingest food as well as by Nomarski interference contrast microscopy, bright field microscopy of protargol‐stained specimens, and by scanning electron microscopy. When placed in a 6% (w/v) urea solution for ∼ 2 min 10 sec, populations of 10,000–100,000 cells shed a large part of their OA. In more than 90% of the cells that shed, the discarded segment is comprised of the apical membranelles, most of the adoral membranelles, and of a variable part of the buccal tube. After washing and incubation at 26°C, 50% of the cells regenerate a functional OA in 4 h 47 min, and after 5 h 26 min, 90% of the cells are able to ingest food. At any given moment during the process, 50–90% of the cells are morphologically in the same stage of RG. Seven stages (among which three are divided into two substages) of RG are defined. The process begins by the disorganization of the remnant oral structures. Concomitantly, kinetosomes multiply along the kineties of the zone of discontinuity and form the longitudinally oriented oral primordium. The latter gives rise to the adoral primordium, which rapidly produces the adoral zone of membranelles (AZM), and to the paroral primordium, which subsequently forms the apical membranelles, the buccal peristomial kineties, and the paroral kinety. Morphogenetic movements lead to incurvation of the AZM and the frontal field and to invagination of the buccal tube.

Changes in the organization of the microfilamentous cortical cytoskeletal system during oral regeneration in Climacostomum virens (ciliate)

“…The release of the OA was achieved according to the procedure described by Fahrni [7] which leads to a large number of synchronized regenerating cells.…”

Stomatogenesis during metamorphosis of Eufolliculina uhligi (Ciliophora, Heterotrichida)

“…Cross-sections through newly formed cilia (Figs. 8,9) suggest that the central microtubules grow out consecutively. Occasionally, cilia with two axonemes, one complete and one incomplete, can be observed.…”