3H]Uridine incorporation during previtellogenesis and early vitellogenesis in the oocytes of the chick (Gallus gallus)

Abstract

ABSTRACT During the weeks following hatching of poultry, oocyte differentiation is most advanced in the central part of the ovarian cortex. For instance, in the 5-day-old chicken, oocytes surrounded by a ring of cuboidal cells (constituting early follicles) are appearing in the central part of the cortex. At the extreme periphery of the same cortex one occasionally can find a few germ cells which are still in the late preleptotene, and often all the intermediate stages can be seen at inter-mediate localizations. D’Hollander (1904) has described the different types of oocytes that can be found during the days following hatching. His investigations indicate that during the so-called extrafollicular phase the nucleus probably passes out of pachytene and into a stage when the chromatin is found in heavy filaments split longitudinally in places. Later the cells go through a pseudo-reticular stage in which the nucleoli and the nuclear membrane have reappeared. Between the fifth and the twentieth day after hatching, the intrafollicular phase sets in and the chromatin may also be found in the form of chains (chiasmata), clearly indicating the diplotene stage. From this stage it passes through a granular stage and becomes progressively retracted from the nuclear wall, finally giving ‘barbed’ or lampbrush chromosomes. In the 20-day-old chick, numerous oocyte nuclei with a lampbrush configuration and a large nucleolus can be seen.