First published online July 2, 2004
Journal of Experimental Biology 207, 2835-2844 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01089
Extracellular H+ dynamics during oogenesis in Rhodnius prolixus ovarioles
C. S. Bjornsson1 and
E. Huebner2,*
1 Laboratory of Nervous System Disorders, Wadsworth Center, Albany, NY
12201-0509, USA
2 Department of Zoology, University of Manitoba, Winnipeg, MB, Canada R3T
2N2
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Fig. 1. An illustration depicting the positions along adult ovarioles of different
stages measured during a scan. As the connective stalk (see stage 4) and the
anterior region of the T and T-1 follicle (stages 8–9) became more
complex, additional points were introduced to include measurements of these
dynamic and potentially interesting regions.
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Fig. 2. Examples of H+ influx and efflux. 2-D vectors were calculated
from measurements taken near the ovariole and 10 µm away in the x-
and y-axis, and superimposed over an image of the ovariole. Vectors
were classified as influx if the vector traveled over the ovariole image
(left), or as efflux if the vector traveled away from the ovariole (right).
Ion concentration gradients are shown as red gradients representing influx
(left) or efflux (right).
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Fig. 3. Mean extracellular H+ fluxes along adult Rhodnius
ovarioles. (A) H+ flux magnitude and direction (influx/efflux)
relative to position along ovariole and ovariole stage
(N=10–18, shown in parentheses). The data for each ovariole
stage, represented by fluctuating black lines running through the coloured
region of the plot, are superimposed on each other making it difficult to show
stage differences. However these are clearly discerned in a top view as seen
in (B). The colour coding indicates H+ flux magnitude and
direction, which is calibrated in B. Each vertical column on the surface plot
corresponds to a specific point along the ovariole as indicated by the
ovariole images. The leftmost column displays background noise. Horizontal
rows display the average H+ flux for each ovariole stage (see
Materials and methods). Prominent efflux occurs near the interfollicular
stalks on either side of the T follicle. H+ efflux at the anterior
stalk is greatest around stage 4 (early vitellogenesis) and declines gradually
until stage 8 (late vitellogenesis) when it is significantly diminished.
Stage-8 ovarioles were also characterized by the appearance of H+
influx along the anterior columnar epithelium of the T follicle.
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Fig. 4. Light micrograph of a stage-9 ovariole with corresponding extracellular
H+ fluxes superimposed. H+ flux is indicated by red
vectors, with length proportional to the flux magnitude. Vector angles are the
result of summing x- and y-axis measurements. Vectors
traveling away from the ovariole surface represent H+ efflux;
vectors traveling over the ovariole are influx. The noise measurement is in
the bottom left corner. Of interest is the H+ efflux near the
forming chorion rim in late vitellogenic oocytes (asterisk), which remains
throughout choriogenesis. Red scale bar, 100 fmol cm–2
s–1; black scale bar, 100 µm.
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Fig. 5. Light micrograph of a recently ovulated follicle with corresponding
extracellular H+ fluxes superimposed. The chorionated oocyte was
loosely contained by the follicular epithelium, and fell away from the
ovariole during dissection. H+ efflux in the region of the rim is
still present after ovulation (asterisk), suggesting follicle cells generate
this H+ flux. Red scale bar, 100 fmol cm–2
s–1; black scale bar, 100 µm.
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Fig. 6. Light micrograph of the anterior portion of a T-1 follicle from a stage-9
ovariole with corresponding extracellular H+ fluxes superimposed.
Additional measurements near the H+ efflux along the T-1/T-2
junction reveal that the efflux extends to the anterior pole of the T-1
follicle (asterisk). These follicle cells presumably are also involved in
interfollicular stalk morphogenesis, and will ultimately form the columnar
cells at the anterior pole of the follicle. Red scale bar, 100 fmol
cm–2 s–1; black scale bar, 100 µm.
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Fig. 7. Light micrograph of a longitudinal section through the interfollicular
stalk separating T-1 (top) and T follicle (bottom). The ovariole sheath is
still intact. The three positions measured along the stalk are shown as red
dots, from anterior (top) to posterior (bottom). Two groups of cells are
present near the posterior stalk position: the stalk cells which are not
dye-coupled to either adjacent follicle (a), and follicle cells which are
coupled to the T oocyte (b). Semi-thin section stained with 1% Toluidine Blue
in 1% Borax. Scale bar, 20 µm.
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© The Company of Biologists Ltd 2004
