Christopher's stages of ovarian development are redefined in Culex pipiens quinquefasciatus to provide a more useful description of mosquito physiology. During this ovarian development, seven growing stages of the oocyte are observed in the adult stage. Two distinct periods of egg follicle growth, the previtellogenesis and vitellogenesis, are seen first. The gradual increase in the oocyte size during these phases is attributed to yolk deposition. During vitellogenesis, the oocyte and nurse cell nucleus are similar in size (stage I). Then, the oocyte enlarges and occupies one third of the egg follicle, while the nurse cell (NC) occupies the remaining two thirds. At this phase, the yolk granules (stage III) enlarge, occupying about half of the egg follicle, while the NC contain the other half (stage IV). An increase and accumulation of yolk granules leads to the filling of about three fourths of the egg bulk and makes the oocyte nucleus hardly visible during stage V. The oocyte undergoes a remarkable growth, occupying nine tenth of the length of the follicle in stage VI. Stage VII corresponds to a mature cigar-shaped egg and contains two kinds of yolk globules: a large one and a small one. The oocyte and the NC at all stages are surrounded by a single layer of epithelial cells which increase in number and form the vitelline membrane and the chorion. The mitochondria in the NC, oocyte, and follicular epithelium appear in light microscopy as granules of different sizes. The Golgi apparatus appears in different sizes and shapes, since in the early stages of development, it is restricted to the perinuclear zone. When the development proceeds, it enlarges in size, spreads over the whole cytoplasm, and participates in the formation of the yolk.

Age determination technique of mosquitoes was described for An. pharoensis Theobald from Egypt by observing the ovarian changes before and through the gonotrophic cycles. During this ovarian development cycle, seven growing stages of the oocyte were observed in the adult stage. Two distinct periods of egg follicle growth, the previtellogenesis and vitellogenesis, were seen first. The gradual increase in the oocyte size during these phases was attributed to yolk deposition. During vitellogenesis, the oocyte and nurse cell nucleus were similar in size (stage I). Then, the oocyte enlarged and occupied one third of the egg follicle, while the nurse cell (NC) occupied the remaining two thirds. At this phase, the yolk granules (stage III) enlarged, occupying about half of the egg follicle, while the NC contained the other half (stage IV). An increase and accumulation of yolk granules led to the filling of about three fourths of the egg bulk and made the oocyte nucleus hardly visible during stage V. The oocyte undergone a remarkable growth, occupying nine tenth of the length of the follicle in stage VI. Stage VII corresponded to a mature cigar shaped egg and contained two kinds of yolk globules: a large one and a small one. The oocyte and the NC at all stages were surrounded by a single layer of epithelial cells which increased in number, forming the vitelline membrane and the chorion. The mitochondria in the NC, oocyte, and follicular epithelium appeared in light microscopy as granules of different sizes. The Golgi apparatus appeared in different sizes and shapes, since in the early stages of development, it is restricted to the perinuclear zone. When the development proceeded, it enlarged in size, spread over the whole cytoplasm, and participated in the formation of the yolk.

Since Culex pipiens quinquefasciatus is the main vector of lymphatic filariasis in tropics and subtropics, the identification and quantification of this mosquito is an important task. Scanning electron microscopy reveals that morphological changes during larval development as the number of comb scale varies greatly and their complexity increases from first to the fourth instar. Also, their structures are more complex with a varying number of subapical denticles. The amount of pecten shows modifications at different larval instars with regard to the number and complexity of their spines. The pecten teeth increase in their number and complexity during development. The number of lateral palatal brush filaments increases during larval development from the first to the fourth instar. The ventral brush of the abdominal segment X in the first and second instars is composed of two respectively three pairs of setae while the third and fourth instars have four pairs of sturdy setae.

The formation and uptake of the yolk protein in the oocyte of the Asian Tiger, Aedes albopictus mosquito was investigated. Light and electron microscopy of the ovaries at early resting stage as well as the structural changes associated with yolk formation were described 16 h after blood meal. The deposition of the yolk protein in the oocyte was correlated with a 15-fold increase in 138-μm pit-like depressions on the oocyte surface. These pits result by invagination of the oocyte cell membrane. They have a 20-μm bristle coat on their convex cytoplasmic side and a layer of protein on their concave extraoocyte space. The pits, by pinching off from the cell membrane become bristle coat vesicles which carry the adsorbed protein into the oocyte. These vesicles lose the coat and then fuse to form small crystalline yolk droplets, which subsequently coalesce to form the large protein yolk bodies of the mature oocyte. Preliminary radioautographs and certain morphological features of the fat body, ovary, and midgut, suggest that the midgut is the principal site of the yolk protein synthesis in A. albopictus.

Dengue fever is a worldwide health problem transmitted mainly by Aedes albopictus.The ability of female mosquitoes to transmit disease depends on their behavioral responses to locate their host. The presence of different types of sensory sensilla with different morphological characteristics is the most distinctive feature of Ae. albopictus, in addition to the main sensory organs. The sensory sensilla are chemosensory contacts that Ae. albopictus uses to locate long-distance hosts and oviposition sites by receiving well-defined cues such as changes in temperature and humidity, mechanical impact, and odors. As a result, it is crucial to study the sensory sensilla of Ae. albopictus. Although the sensory sensilla of Ae. aegypti have been extensively studied, but there is still a lack of knowledge about the sensory sensilla of the Asian tiger mosquito, Ae. albopictus. This study aimed to investigate the different types of sensory sensilla