title: The behavior during pachynema of a normal and an inverted Y chromosome in Microtus agrestis.
abstract: The pachytene behavior of the chromosomes of Microtus agrestis (L.) (Rodentia, Arvicolidae) males carrying either the standard, or the pericentrically inverted Lund Y chromosome have been examined by electron microscopy of microspread spermatocytes. There is no synapsis between the X and either the standard or the Lund Y chromosomes during any substage of pachynema. Since synapsis is generally considered a prerequisite for crossing over, there appears to be no opportunity for crossover or chiasma formation between the X and Y in this species. The G-, C- and NOR-banded mitotic karyotypes of animals carrying the standard and Lund Y are also presented.
authors.forename: T
authors.initials: T
authors.lastname: Ashley
authors.forename: M
authors.initials: M
authors.lastname: Jaarola
authors.forename: K
authors.initials: K
authors.lastname: Fredga
mesh_terms: D000818:Animals; D003411:Arvicolinae / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D008540:Meiosis; D008854:Microscopy, Electron; D008938:Mitosis; D014998:Y Chromosome / Q000502:physiology*