S. Akhtar et Hf. Vanemden, ULTRASTRUCTURE OF THE SYMBIONTS AND MYCETOCYTES OF BIRD CHERRY APHID (RHOPALOSIPHUM-PADI), Tissue & cell, 26(4), 1994, pp. 513-522
As is known for other aphids, the symbiont cytoplasm in Rhopalosiphum
padi is differentiated into a central eccentric and a cortical region
which contains electron-lucent nucleoplasm and DNA fibrils. The cytopl
asm is surrounded by a plasma membrane, cell wall and perisymbiotic me
mbrane which are separated by periplasmic spaces. The periplasmic spac
e between tile cell wall and perisymbiotic membrane contains small ves
icles. The symbionts are packed into mycetocyte cells which contain a
large nucleus and all the normal cell organelles. For the first time,
however microtubules and microfilaments have been identified, but only
at high magnification and evidence has been found which makes it poss
ible to propose a mechanism of vesicular transport.