Gonomery

Gonomery, the phenomenon of more or less prolonged retention of independence by both sexual nuclei—the male and female—after the copulation of two sex cells. Usually the male and female nuclei of a fertilized egg (Metazoa) or zygote (Protozoa) soon merge and form a single and complete syncaryon, which then begins to divide. However, in some groups of organisms, cases of incomplete merging of both sexual nuclei have been described. As a result, when the syncaryon of the fertilized egg (or zygote) and the nuclei of subsequent generations derived from it divide, traces of the dual origin of these nuclei from the male and female gamete nuclei are preserved. Thus, Conklin (1902) in the mollusk Crepidula established that during the first division of the egg syncaryon, two groups of chromosomes—male and female—are observed in the nuclear spindle. The two daughter nuclei resulting from the division of the syncaryon turn out to be double, consisting of two halves, or gonomers—male and female. Gonomery is preserved for a very long time, up to the adult state, in some copepods (Cyclops and others) according to the data of Rücker (1895) and especially Haecker (1896). Here the dual nature of the animal's nuclei is excellently proven by the fact that the nuclei of its cells initially always have two nucleoli (of male and female origin), which only merge together over time. Similar cases have also been described for Protozoa. Thus, in Amoeba diploidea, according to Hartmann and Naegler (1908), both sexual nuclei remain independent throughout the period of asexual reproduction and merge only before the next copulation. V. Dogel observed long-term isolation of gonomers during the conjugation of some infusorians (Cycloposthium). Examples of gonomery are also known from the plant kingdom, namely among Ascomycetes, Basidiomycetes and Conjugatae.