Instar Females Research Articles

Oscillations of oocyte nuclei in the ovarioles of the grasshopper Melanoplus differentials differentials (Orthoptera, Acrididae)

1. 1. Oscillatory movements of the nucleus of the grasshopper oocyte have been observed directly and recorded cinematographically. 2. 2. In young oocytes from first and second instar grasshopper nymphs, independent movements of the chromosomes occur. Arrhythmic movements of the nucleus are first observed in oocytes from third instar females. In older oocytes these movements become rhythmic and oscillatory with a period of from 5 to 45 seconds at 28 °C and with an excursion of from 5 to 20 degrees. The motion resembles that of the balance wheel of a watch. The axis of rotation lies perpendicular to the long axis of the egg. 3. 3. The nuclear oscillations are affected by temperature and pressure but the plane of oscillation is not influenced by natural gravitational forces.