Woo-Kap Kim

HEMOCYTIC DIFFERENTIATION IN HEMOPOIETIC ORGAN OF BOMBYX MORI LARVAE

Abstract Bombyx mori L. (Lepidoptera: Bombycidae) larva was investigated with a transmission electron microscopy to determine hemocytic differentiation in the hemopoietic organ located in the prothorax. Three and/or four types of stem cells in compact islets of the organ were observed. Immatured hemocytes in loose islets of the organ were more differentiated and developed than in compact islets. Four types of hemocytes such as prohemocyte, plasmatocyte, granulocyte and oenocytoid were observed in loose islets. Each type of hemocyte was differentiated from each type of stem cell. However, none of spherulocyte was observed. Each type of hemocytes matured in loose islets was discharged into hemolymph by the tearing of acellular membrane covering the islets. These observation strongly suggests that the four kinds of hemocytes except for spherulocytes first appeared in islets and then moved to the region of loose islets in matured form. The more detailed pathway of hemocytic differentiation in B. mori was represented here.

Axonal pathfinding in developing labial palps of the butterflies, Pieris rapae and Pieris brassicae

SummaryElectron microscopy was used to study the developmental changes in the pupal labial palp of Pieris rapae L. and P. brassicae L. prior to axogenesis of the peripheral receptor organs. Two cells emigrate from the anlage of the labial palp-pit organ (LPPO). They develop growth cones and filopodia, which are directed distally. The filopodia insert into stem cells of the LPPO. The perikarya of the cells proceed into the hemolymph space of the palp such that, eventually, these cells bridge the gap between the LPPO and the apical scolopidial organ (ASO) of the labial palp. This bridge is established at about 11% of total pupal development. Only 6 h later, at 15% of pupal development, the cells are no longer visible. We suggest that these cells are luminal neurons and name them pit-organ luminal (POL) cells. These POL cells may act as primary guiding structures for the axons of the sensory cells of the LPPO, which are assumed to orientate along this structure once they reach the ASO.