Life and Medical Sciences
Cell & Developmental Biology
Wiley InterScience Backfile Collection 1832-2000
The diploid number of twenty-six chromosomes was found in the mature parthenogenetic female-producing eggs and also in the somatic cells of the female embryos developing from such eggs. In the maturation stages of a few of these eggs the chromosomes were markedly larger than in the corresponding stages of the majority of the eggs. Whether this size difference of the chromosomes is correlated with male- and female-producing individuals has not been determined. The mature parthenogenetic male-producing eggs contain the haploid number of thirteen chromosomes, and this number was found also in the somatic cells of the young male embryos. The mature sexual eggs contain thirteen chromosomes.In spermatogenesis the secondary spermatocyte divisions are usually omitted and the secondary spermatocytes develop directly into the motile spermatozoa containing thirteen chromosomes. A few, however, of the secondary spermatocytes divide, forming spermatids containing fewer than thirteen chromosomes. These cells develop into the non-motile and rudimentary spermatozoa.The motile spermatozoa containing thirteen chromosomes unite with the parthenogenetic male-producing eggs containing thirteen chromosomes, thus producing the fertilized eggs with the diploid number of twenty-six chromosomes. These fertilized eggs develop into female-producing females which reproduce parthenogenetically.
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