Dev Biol. 2022 Jan;481:188-200. doi:10.1016/j.ydbio.2021.10.009

Nishida H, Matsuo M, Konishi S, Ohno N, Manni L, Onuma TA.

Germline development during embryogenesis of the larvacean, Oikopleura dioica.

Identified a CAB (centrosome-attracting body) “for the following reasons. (1) There was a clear boundary between the CAB-like region and the general cytoplasm, but the membrane structure did not surround the CAB. (2) It contained an electron-dense matrix that resembled a germplasm. (3) The region was devoid of mitochondria but contained ER. (4) It was present beneath the cell membrane, and the cell surface exhibited microvilli. (5) It was present in the germline lineage cells.” ”The longest diameter of the CAB was approximately 10 ​μm.“ It was observed between the late 8-cell stage and some 1.5-h embryos, but not after 2h. It was stained by the H3S28p rat monoclonal antibody (Abcam ab10543) but not by DAPI. The snail mRNA also colocalises with the CAB's H3S28p staining. A germ body (GB) “appeared [in PGCs] 13 ​min after the 5th cleavage [and] disappeared 1.5 ​h after fertilization at 20 ​°C. It is discussed whether the GB and the CAB are or are not the same structure.