Figure 3.

Schematic representations of the centriole architecture in Drosophila somatic cells (A), primary spermatocytes (B) and sensory neurones (C). Ciliary projections of both spermatocytes and sensory neurons are also depicted. (A) The somatic centrosome of Drosophila, such as vertebrate centrosome, consists of two centrioles, one mother and one daughter, arranged orthogonally to each other, and the pericentriolar material around them (PCM, light blue). Even then both centrioles show a proximal-distal organization, the centriole wall is composed of nine microtubule doublets, each of which presents the complete tubule A, and the tubule B. (B) In Drosophila male gametogenesis, mother and daughter centrioles act both as basal bodies for the ciliary projections. Both the centrioles are composed of nine microtubule triplets and have a distinct cartwheel in their proximal region. The axoneme of the ciliary projections is composed of nine microtubule doublets and the C-remnants. The cell cytoplasm is represented in light yellow. PCM, pericentriolar material in light blue. (C) In Drosophila sensory neurons, the distal and the proximal centrioles are coaxial and lack a distinct cartwheel. The ciliary rootlet (in blue) emerges from the proximal end of the distal centriole and form a cage enclosing the proximal centriole. The proximal centriole consists of mixed singlet and doublet microtubules and it is smaller than the distal centriole that is built by doublet microtubules. The DBB forms an elongated transition zone (TZ) characterized by short lateral projections (in grey) and Y-like structures. The axoneme nucleated by the distal centriole is composed of nine microtubule doublets. The cell cytoplasm is represented in light yellow. PCM, pericentriolar material in light blue.