ABSTRACT
Differentiation of the tissues of the telotrophic ovarioles from the embryonic primordium occurs gradually throughout larval development of bugs. All tissues are established already at the beginning of the last larval stage as ob-served by Wick & Bonhag (1955) in Oncopeltus fasciatus. During the last instar, when the corpora allata are morphogenetically inactive, the synthetic activity of the cells of first ovarian nutritive system, the trophocytes, takes place. The nutrients released by trophocytes at the final emergence activate the oocytes, starting previtellogenesis (Masner, 1966). The function of this nutritive system is known to be independent of any humoral control (Wigglesworth, 1936, and others). Food intake seems to be the only inductor of trophocyte growth. The developing oocyte grows into the prefollicular syncytium. The surrounding tissue starts to organize into a unilayered epithelium.