GONOMERY MEETS ANLAGEN: ON THE ETIOLOGY OF BILATERAL GYNANDROMORPHY IN INSECTA

Abstract

Gynandromorphy is the phenomenon in which an organism exhibits both full male and female characteristics. Gynandromorphy results from genetic mosaicism where two or more cell lineages within an individual have different genotypes, often occurring on left and right sides of the body. It has been observed that a longitudinal line dividing a gynandromorph body into symmetrical left and right sections, corresponding to the division between male and female halves, is heavily preferred. Since most gynandromorphy is due to the loss of a sex chromosome in the first cell division, it is expected that the first division plane would divide the embryo into bilaterally symmetrical left and right sides. However, cytological evidence shows that the plane of the first division of cells is randomly determined during embryogenesis. If the first division plane is truly random, then there should be no preference for a longitudinal dividing line of sex in gynandromorphs. To resolve this contradiction, I hypothesize that the gynanders (gynandromorphic organisms) observed in a population are only a portion of those that occur, leading to a bias. To address this, I used a lineage tracing system to identify which cells came from either side of the first division plane, so that I could relate those to observable gynandromorphs. However, after my experiments, I concluded that the activation of the lineage tracing system occurs too late in development to detect the first division plane, so the question remains unanswered. However, I was able to use the lineage tracing to shed light on the development of salivary gland anlagen early in embryogenesis.