In subsequent grafting experiments, we observed that antibodies raised against this protein detected a type of sponge stem cell, the archeocyte
, that accumulated in the contact zone of allografts (between tissue from different individuals), but not of isografts (between genetically identical tissues).
The large archeocyte in Figure 9 has, however, neither minute ellipsoid granules nor residual axonemes.
In contrast, when sufficient numbers of choanocytes are supplied by larval flagellated cells, the archeocyte differentiation to choanocytes is probably unnecessary.
In the latter view, choanocytes are thought to derive from archeocytes.
Figure 8 shows the distribution of diameter of the nuclei of nucleolated amoeboid cells and archeocytes in the metamorphs.
The cells that remain, primarily archeocytes, become encased in relatively dense supporting tissue that offers protection from adverse conditions (1).
non-apoptotic) cells, which we interpret as archeocytes or stem cells.
However, we were unable to differentiate between the cell types in the mesohyl (between the pinacocyte layers) including rhabdiferous cells, archeocytes
, and gray cells.
This effect is especially pronounced on the larger cell forms, probably archeocytes
A mixed pattern of stained and nonstained cells was found, with the most intense staining present intracellularly and on surface membranes of the larger cell population, including cells interpreted as archeocytes
The spermatozoa appear to develop from archeocytes [ILLUSTRATION FOR FIGURE 1 OMITTED].
As in the present study, the development of sperm from archeocytes has been documented among other sponges as well, although spermatozoids are generally thought to develop from choanocytes (Reiswig, 1983).