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 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.
Like archeocytes, some of the amoeboid cells have a nucleolus, but these cells are smaller and have fewer phagosomes than the archeocytes.
During growth and differentiation, sponge presents a variety of cell types derived from stem cells (archeocytes) and organized in the context of a fibro-silicaceous framework.
Winter sections displayed large fragments of apoptotic debris intermingled with an almost uniform population of large counterstained (i.e., 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
. Peroxidase staining was less intense in cell preparations that had not been desulfated (1A), indicating that sulfate is masking HA binding sites.
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).