Corbiculacean Gill Morphology - The Eu-latero-frontal Cells
Eu-latero-frontal (ELF) cells are situated on the upper portion
of the gill filament and form part of the arch of the filament.
The ELF cirri, sometimes referred to as "plates," are
thought to be part of the filtering mechanism of the gill. The
mechanism is composed of apposed ELF cirri extending toward one
another to form a "net" of sorts (McMahon, 1991). Water
is driven through this "net" by lateral
cilia and the suspended particles are trapped and transferred
to the frontal cilia where they are
conducted to the food groove. There
is some debate as to whether secreted mucous plays a significant
role in the capture of particles.
Below are some images of eu-latero-frontal cells and cirri.
An SEM of the ELF cirri of Musculium partumeium. Also
visible are one frontal cirrus (upper
left quadrant). Approximate magnification of the original photo
Detail of 1. The distal portions of many of the ELF cirri
are visible, giving the cirri a "feathery" appearance.
Approximate magnification of the original photo - 2.8kx.
A closeup of the ELF cirri of M. partumeium. Note
that the dual sets of fused cilia that compose each "plate"
are visible. Approximate magnification of the original photo
A closeup of the ELF cirri of M. partumeium. Again
visible are the dual sets of fused cilia that compose each "plate."
Also visible in this micrograph are the distal, finger-like portions
of the ELF cirri, the individual cilia that compose the cirrus,
and the lateral cilia (bottom right quadrant). Approximate magnification
of the original photo - 5.2kx.
- 5. A TEM
section through the gill filament of C. fluminea at the
level of the ELF cells. This micrograph shows that the pairs
of fused cirri that compose the "plates" issue from
a single cell. A;so visible within this photo are the lateral
cilia (a mass of cilia in cross section on the right side of
the phto) and what appears to be a mucous strand (dark material
running between the lateral cilia and the ELF cirri. Approximate
magnification of the original photo - 3kx.
Detail of 5. This micrograph shows the pairs of cilia issuing
from a single cell. In addition, this image shows that between
each of the two "plates" of the ELF cirri, there is
a single microvillus. Lastly, the image shows the ciliary rootlets
that are bound to each cilium of the ELF. Also note that the
rootlets on a given side of each of a pair of cilia cross to
that side of the cell and end near the cells' membrane.
A TEM of a section through the gill filament whose plane
is at an approximate right angle to that shown in 5 and 6. In
the lower half of the micrograph, at least one ciliary rootlet
can be traced from the base of one of the cilia, across the cell,
to the cell membrane. The roolets are visible as dark lines in
A TEM of a section in nearly the same plane as 6. This photo
shows the fused cilia that compose the ELF cirrus.
McMahon, RF. 1991. Mollusca:Bivalvia. Pp315-399. in</>
Ecology and Classification of North American Freshwater Invertebrates.
JH Thorp and AP Covich,eds.. Acedemic Press, Inc. New York.
Back to image of gill.