In the following example a pericentric inversion generates a metacentric chromosome from an acrocentric chromosome. Inversions are not easily detected in homozygotes of other species, unless as with humans, distinct chromosomal banding patterns have been established for normal members of that species. Heterozygotes derived from a cross of a normal individual and an individual with an inversion in one chromosome will have specific patterns that occur because of pairing problems. In Drosophila, polytene chromosome will contain loops, evidence that one of the synapsed chromosomes contains an inversion. The appearance of meiotic chromosomes also will be affected if one of the chromosomes has an inversion.
Loops appear and define the region in which the inversion has occurred.
Furthermore, if recombination occurs in a paracentric inversion region, then one-half of the gametes will be normal and the other half will contain deleted chromosomes. If the recombination involves a pericentric inversion then one-half of the gametes will be normal with respect to the initial chromosomal arrangements and the other gametes will contain chromosomes that contain both additions and deletions. These abnormalities can generate unbalanced gametes and in general, individuals with pericentric inversions are reproductively inferior. In general, inversions do not change the phenotype of the individual unless an excision site of the inversion is within the regulatory or structural region of a gene. The primary change that is seen with inversions is a change in linkage relationships.