Using time-lapse video microscopy, we found that ooplasmic inclusions in the fertilized medaka egg displayed two types of movement during ooplasmic segregation. The first manifested itself as the movement of many inclusions (diameter = 1.5-11 μm) toward the animal pole at about 2.2 μm min-1; this type of movement appeared to be streaming. The second type of movement was faster (about 44 μm min-1) and saltatory; inclusions displaying this type of movement were smaller (diameter ≤1.0 μm) and moved toward the vegetal pole. The movement of oil droplets toward the vegetal pole of the egg may represent a third type of motion. All these movements began only after a strong contraction of the ooplasm toward the animal pole, which at 25°C began 10-12 min after fertilization and <3 min after formation of the second polar body. In eggs treated with microtubule poisons--colchicine, colcemid, or nocodazole--oil droplets did not move toward the vegetal pole, saltatory motion toward the vegetal pole was absent, and the growth of the blastodisc was slowed. Eggs treated with β-lumicolchicine, an inactive derivative of colchicine, showed normal movements. Colchicine, while not inhibiting formation of the second polar body, did inhibit pronuclear migration. These results suggest that microtubules are involved in the movement of some ooplasmic inclusions, including oil droplets, toward the vegetal pole; the movement of ooplasmic inclusions toward the animal pole; and pronuclear migration.

Accurate identification of Anopheles using different techniques is essential for having effective malaria control strategies. Present study describes the eggs of species belonging to subgenus Cellia of genus Anopheles collected from North India using scanning electron micrographs. An. annularis are sympatric with major malaria vectors like An. culicifacies, An. stephensi and An. maculatus. The eggs of the Anopheles species described so far are boat-shaped with rounded anterior and posterior ends. However, they can be easily distinguished by the shape of the deck present on the ventral (upper) surface of the egg. In An. annularis the deck is continuous along the length of the egg. The restricted deck in some species is due to presence of chorionic cells on the upper surface of the eggs. The floats (structure present on the lateral side of the eggs) in some Anopheles species are located in the middle of the egg and are limited to the lateral sides. In An. annularis the floats extends up to anterior and posterior frills(slight wavy structures present on both the ends of an egg). The eggs are compared with related species of genus Anopheles, notably An. culicifacies, An. splendidus and An. stephensi. It was found that An. annularis can be easily distinguished from other sympatric species by egg morphology study. How to cite this article: