germ cell cluster formation and ovariole structure in viviparous and oviparous generations of the aphid stomaphis quercus. | the developing ovaries of s. quercus contain a limited number of oogonial cells which undergo a series of incomplete mitotic divisions resulting in the formation of clusters of cystocytes. ovaries of viviparous generations contain 6 to 9 clusters, containing 32 cystocytes each, whereas ovaries of oviparous generations contain 5 clusters containing 45-60 cystocytes. during further development, clusters become surrounded by a single layer of follicular cells, and within each cluster the cystocytes ... | 2008 | 18311716 |
the structure of extremely long mouthparts in the aphid genus stomaphis walker (hemiptera: sternorrhyncha: aphididae). | scanning electron microscopy and light microscopy were used to elucidate the morphology of labium and mandibular and maxillary stylets of the aphids stomaphis quercus (l.) and s. graffii cholodkovsky. the mechanism of labium shortening associated with feeding process was described as well. stomaphis quercus and s. graffii have cone-shaped labium of 13 and 10 mm in length, respectively, that strongly extend behind the abdomen. the stylets bundle comprises a pair of mandibular and maxillary stylet ... | 2017 | 26346957 |