REORGANIZATION OF MICROTUBULE ARRAYS IN THE TELOTROPHIC OVARIES OF HEMIPTERAN INSECTS - CORRELATION WITH MEIOTIC REINITIATION

We have shown that, in the ovaries of hemipteran insects, microtubule reorganisation and depolymerisation in the oocytes, and in the nutriti ve tubes supplying them, correlate with the activation of M-phase prom oting factor (MPF) and mitogen-activated protein kinase (MAP kinase) a s the oocytes proceed to arrest at the first meiotic metaphase. The ap plication, however, of Xenopus egg extracts with high MPF activities t o isolated nutritive tube microtubules failed to result in their depol ymerisation, suggesting that a novel factor may be required for the br eakdown of these highly stable microtubule arrays in vivo.