Slipper Animalcule

Paramecium (caudatum) (par-a-mee-see-um) is a very familiar genus of ciliates. They eat bacteria and have the mouth recessed in a buccal cavity, and the cell is often shaped with a scoop leading to the mouth. There are cilia all over the body with a caudal tuft of longer cilia at the back of the body. Usually with a layer of extrusomes (trichocysts) under the cell surface and a large oval macronucleus. Contractile vacuoles star-shaped. This species is P. caudatum, and was photographed with the cell pushing itself into some debris. This is the normal feeding behaviour of this genus. Phase contrast.

Paramecium (caudatum) (par-a-mee-see-um) is a very familiar genus of ciliates. They eat bacteria and have the mouth recessed in a buccal cavity, and the cell is often shaped with a scoop leading to the mouth. There are cilia all over the body with a caudal tuft of longer cilia at the back of the body. Usually with a layer of extrusomes (trichocysts) under the cell surface and a large oval macronucleus. Contractile vacuoles star-shaped. Most species are elongate, although this particular individual has been squashed so that we can see the nuclei. The (morpho)species are distinguished by morphology of the nuclei. This species is P. caudatum, which a single rather globular macronucleus lying alongside (4 o clock) the macronucleus. Phase contrast.

Paramecium (caudatum) (par-a-mee-see-um) is a very familiar genus of ciliates. They eat bacteria and have the mouth recessed in a buccal cavity, and the cell is often shaped with a scoop leading to the mouth. This cell has been compressed so that we can see various organelles. There are cilia all over the body with a caudal tuft of longer cilia at the back of the body. Usually with a layer of extrusomes (trichocysts) under the cell surface and a large oval macronucleus. Contractile vacuoles star-shaped. Phase contrast.

Detail of the oral apparatus and surrounding infraciliature (anterior ventral aspect) of the hymenostome ciliate Paramecium caudatum (Ehrenberg, 1833). The preoral and postoral sutures (lines of convergence of kinetal fields) can be clearly seen. The kinetids with their kinetodesmal fibers are clearly visible. The kinetodesmal fibers are periodically striated bundles of fibrils arising near the base of somatic kinetids (the posterior one if kinetids are paired) in ciliates. The kinetodesmal fibers extend anteriorly and to the right of their kinety (this is the Law of desmodexy). This provides a means of determining an anterior, posterior and right/left orientation in ciliates. Here the kinetodesmal fibers are longer than the interkinetal distance and therefore overlap giving the appearance of a longitudinal interkinetal line. The macronucleus and the single large micronucleus are seen anterior to the oral aperture. Silver carbonate stain (see Foissner, W.Europ. J. Protistol.27,313-330;1991). Specimen collected from freshwater pond near Boise, Idaho July 2004. Brightfield.

These two individuals have fused toigether and wille xchange haploid nuclei as part of a process of sexual activity. Ciloiates can divide asexually with mitotic division of the micronuclei and an a-mitoitic division of the macronucleus. Periodically, the cells go through a sexual process in which cells join at the mouth region, the macronucleus breaks down, micronuclei undergo meiosis, haploid nuclei are exchanged, they then fuse and the resulting product divides to create new micronuclei and macronuclei.

In this stained preparation, the nuclei are red. There is a single normal cell, a pair of cells joined in conjugation and two cells in the process of asexual division - which involves a division furrow cutting through the middle of the cells.

This single cell has been fixed and stained with a dye that shows up the nuclei. The image clearly shows the large macronucleus and the smaller, but still substantial. micronucleus. The arrangement of the nuclei is one of the criteria used to distinguish the species in this genus.

Passion. This image goes with the one of Eufolliculina. In this case this is a knitted contractile vacuole with the radiating canals, ampullae, vacuole and vacuolar pore. Knitted by June Hornby.

Higher magnification that shows the bilayer nature of the ciliary membrane (cm), plasma membrane (pm) and the outer (oam) and inner (iam) alveolar sac membranes of the alveoli (al). The 9-doublet + 2-singlet microtubular axonemal system of the cilium is seen in cross section (also see Figure 8). Two dynein arms (arrowheads) extend from each doublet. Cacodylate buffered fixative. EM taken on 9/27/68 by R. Allen with Philips 300 TEM. Neg. 60,400X. Bar = 0.1 micron. This image is available in Richard Allen's collection.  

Detail of the oral apparatus and surrounding infraciliature (anterior ventral aspect) of the hymenostome ciliate Paramecium caudatum (Ehrenberg, 1833). The kinetodesmal fibers are periodically striated bundles of fibrils arising near the base of somatic kinetids (the posterior one if kinetids are paired) in ciliates. The kinetodesmal fibers extend anteriorly and to the right of their kinety (yellow arrowheads). This is the Rule of Desmodexy which states "true kinetoodesmata,when present, lie to or extend (anteriad) to the 9organism's) right of the kinety (line of kinetosomes) with which they are associated". This provides a means of determining an anterior, posterior and right/left orientation in ciliates. Here the kinetodesmal fibers are longer than the interkinetal distance and therefore overlap giving the appearance of a longitudinal interkinetal line (blue arrowhead). The macronucleus and the single large micronucleus are seen anterior to the oral aperture. Silver carbonate stain (see Foissner, W.Europ. J. Protistol.27,313-330;1991). Specimen collected from freshwater pond near Boise, Idaho July 2004. Brightfield.

Detail of the oral apparatus and surrounding infraciliature (anterior ventral aspect) of the hymenostome ciliate Paramecium caudatum (Ehrenberg, 1833).between the two sets of yellow arrowheads are the four loosely spaced kineties of the "quadrulus" (M3). The pink and light blue arrowheads mark the first (M1) and second (M2) adoral membranelles.Silver carbonate stain (see Foissner, W.Europ. J. Protistol.27,313-330;1991). Specimen collected from freshwater pond near Boise, Idaho July 2004. Brightfield.