The Structure and Formation of Cilia and Filaments in Rumen Protozoa

Abstract

The large oligotrich rumen protozoa Diplodiniurn ecaudatum and Ophryoscolex caudatus have been studied by electron microscopy during interphase and division. The structure of mature cilia is contrasted with that seen during their formation particularly in a tuft where development lags and is arrested. Here the shaft is only a few micra long and is composed of filaments that have circular cross-sections not in the typical circular arrangement. In their diameter and appearance the filaments are similar to filaments associated with the nuclei during division. The macronucleus has within it randomly directed filaments, while the micronuclcus contains well aligned filaments and other arrangements typical of an intranuclear mitotic process. An extranuclear filament system is also present and is elaborated during division. The infraciliary filament system is particularly elaborate in these organisms.Filaments ranging from 14 to 22 m# have been observed with some tendency for a bimodal distribution in diameters of 15 and 21 m#. Formation of such filaments has been observed and consists of an initial orientation of very fine elements followed by filament formation. The observations are discussed in relation to filament involvements in cell movements. The concepts are discussed that filaments are metastable structures and that the transitions from one state to another are functionally significant.

An Ultrastructural Study of Plant Spermatogenesis

“…The paired centrioles of most animal cells undergo replication at a specific time during division and apparently play a role in the architecture of the spindle (Amano, 1957;Inout, 1964;Roth and Shigenaka, 1964;Krishan and Buck, 1965;Murray et al, 1965).…”

A Structural Basis for How Motile Cilia Beat

“…Satir (1963Satir ( , 1965 reasoned that, after such a quick fixation, examining the fine structure of the axoneme of cilia captured in different positions would show how contraction occurred. What to examine was not obvious, but then Roth and Shigenaka (1964) showed that, in certain axonemes, the tips did not retain the 9+2 pattern; some of the doublets became singlets. One could imagine that if some of the doublets contracted to bend the cilium in-say-the direction of the effective stroke, the doublets that contracted would become singlets and would disappear from the tips before the doublets on the opposite side (that of the recovery stroke).…”

ELECTRON-MICROSCOPIC OBSERVATION ON NUCLEAR EVENTS DURING BINARY FISSION IN <i>BLEPHARISMA WARDSI</i> (CILIATA, HETEROTRICHIDA)

“…In Diplodium (Roth and Shigenaka 1964) they were found on the inside as well as on the outside of the macronucleus during division. In the present species, they are found only in the cytoplasm outside the nuclear envelope.…”

“…Microtubules were observed in the stage of the macronuclear division in several species of ciliate (Roth and Minick 1961, Roth and Shigenaka 1964, Raikov 1965, Carasso and Favard 1965, Suganuma and Inaba 1967.…”