GSCs give rise to mitotic precursors of oocytes, called oogonia. Oogonia divide multiple rounds with incomplete cytokinesis, retaining cytoplasmic bridges between sister-cells and forming a cellular organization, called the germline cyst. The induction of meiosis transform oogonia to differentiating oocytes, which continue to develop in the cyst before leaving to form the primordial follicle. The cyst harbors critical processes during those stages, including meiotic chromosomal pairing, the bouquet and zygotene cilium, as well as oocyte symmetry breaking. Thus, the germline cyst serves as a hub for follicle production.
The cyst is conserved from insects to mammals, and is well characterized in drosophila. In contrast, the vertebrate cyst is poorly understood. The number of cells in the cyst and their pattern of division which construct it, its cell connectivity, and importantly – the function of the cyst, are all unclear. We have developed methodologies to investigate this cellular hub, by advanced microscopy and automated deep-learning segmentation and analyses, cutting-edge 3D electron microscopy (SBF-SEM), and live manipulations (Kumar and Elkouby, 2023, Development).
Equipped with this toolkit, we are now working to resolve the cell division mechanisms the underly cyst construction, identify developmentally relevant cell-cell communication in the cyst, and extract biologically relevant physical parameters of cyst cells by automated algorithms. Cyst-like organizations also form outside the germline in various morphogenetic and embryonic contexts.
Our work will advance our understanding of the structure and function of such cellular organizations in development. For example, our data already begin to uncover that the cyst architecture contributes to guiding the early regulation of the oocyte centrosome MTOC machinery towards bouquet formation in meiosis and oocyte polarity.
