Fig. 7
Male meiosis of Panstrongylus howardi (2n = 20 A + X1X2Y) (a–d) and male interspecific hybrids resulting for the crosses between P. howardi (♀) and P. chinai (♂) and the reverse cross (e–h). a–c C-banding technique. d Fluorescent in situ hybridization (FISH) with 45S ribosomal DNA probe. e–h Giemsa stain. a Diplotene. The ten autosomal bivalents are clearly observed and showing heterochromatic C-blocks in both chromosomal ends. The three sex chromosomes remain associated (arrowhead). b Metaphase I. The ten autosomal bivalents and the three sex chromosomes (univalents) appear clearly separated. c Metaphase II. Typical chromosome configuration seen in Triatominae species: the three sex chromosomes in the center of a ring formed by the autosomes. The X1 and X2 chromatids segregate to the same pole, while the Y chromatid migrates to the opposite one. d Metaphase I. The 45S rDNA signals are located in one of the largest autosomal bivalent. e Paquitene stage. Chains of bivalents, univalents and even chromosomal fragments are observed, products of the alteration of chromosomal pairing. f Late diplotene. Associated bivalents (arrowheads) and univalents (arrows) can be observed. Metaphases I (g) and Metaphases II (h) altered, with deficiency or excess of autosomes and sex chromosomes