Nurse cell-oocyte interaction in the telotrophic ovarioles of an insect, Rhodnius prolixus.

Microinjection of intracellular tracers fluorescein, Procion Yellow, Lucifer Yellow and horseradish peroxidase unequivocally showed the syncytial structure of the tropharium and its interaction with the oocytes. The tropharium tip is a separate isolated compartment. Finger-like nurse cell projections comprising the syncytial tropharium interact via gap junctions along their abutting membranes and also via large cytoplasmic continuities at the central trophic core. The trophic cords connecting the tropharium to oocyte vary in diameter relative to oocyte stage. Continuity of the tropharium with the oocytes is lost at approximately 1000 micron oocyte length and the severed cords then regress from the oocyte to the tropharium base. Variation in cord diameters and timing of cord closure may account for the highly regulated sequential oocyte growth.