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Programmed cell death of the ovarian nurse cells during oogenesis of the silkmoth Bombyx mori
Author(s) -
Mpakou Vicky E.,
Nezis Ioannis P.,
Stravopodis Dimitrios J.,
Margaritis Lukas H.,
Papassideri Issidora S.
Publication year - 2006
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.2006.00878.x
Subject(s) - nurse cell , cytoplasm , bombyx mori , microbiology and biotechnology , vacuole , biology , vitellogenesis , programmed cell death , cell , autophagy , apoptosis , oogenesis , oocyte , genetics , gene , embryo
In the present study, we describe the features of programmed cell death of the ovarian nurse cells occurring during vitellogenesis of the silkmoth Bombyx mori . At developmental stage 5, the nurse cells occupy one‐half of the follicular volume and obtain a rather spherical shape, while the nurse cell nuclei appear large and elongated, forming impressive projections. At the following stage, stage 6, the nurse cells decrease in size and their shape becomes elliptic. The nuclei remain elongated, being also characterized by large lobes. The lobes of the ramified nurse cell nuclei seem to retain the nucleus in the center of the cell during the dumping of the nurse cell cytoplasm into the growing oocyte. At stage 7, membrane enclosed vacuoles can be easily detected into the nurse cells cytoplasm. Ultrastructural analysis and fluorescent microscopy using mono‐dansyl‐cadaverine staining of these vacuoles also reveal that they represent autolysosomes. Caspase activity is detected during stage 7, as it is demonstrated by using the Red‐VAD‐FMK staining reagent. At developmental stages 8 and 9, the nurse cells exhibit chromatin condensation, DNA fragmentation and caspase activity. Finally, during the following stage 10, the nuclear remnants are assembled into apoptotic vesicles, which, after being phagocytosed, are observed in the cytoplasm of adjacent follicle cells. We propose that apoptosis and autophagy operate synergistically during vitellogenesis of B. mori , in order to achieve an efficient and rapid clearance of the degenerated nurse cell cluster.