KINETIC ANALYSIS OF ENTIRE OOGENESIS IN XENOPUS LAEVIS

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Abstract
Without artificial hormonal stimulation, 2 yr after metamorphosis are necessary for a X. laevis female to produce mature oocytes. Four periods of different growth rates are distinguished in this 1st wave of oogenesis: oocytes reached 120 .mu.m in diameter (early stage I according to Dumont) in a few weeks after metamorphosis; growth slows down and the size of 250-300 .mu.m (late stage I) is obtained 6-7 mo. later; a rapid growth resumes during vitellogenesis (stages II, III and IV) and a 1000-1100 .mu.m diameter is reached in 2-3 mo.; the last period lasts for a year and the oocyte grows up to 1200 .mu.m. This phase covers many physiological changes and it should be critical to size carefully the oocytes for biochemical investigations and comparisons. Most oocytes in a young female do not proceed through this entire oogenesis; they are stopped at the end of the 2nd growth phase (.apprx. 250 .mu.m in diameter).