Histological observation on the mantles in some freshwater mollusksindicate that the connective tissue of the mantle originate from cell-polymerized-mass(CPM). The cytogenesis of CPM usually take place in a kind of sac structureand the reproduction of cells inside the sac can form many 3 to 20 GPM that dissi-milar in size, each are made up of a large number of cells with no intercellular sub-stance. As CPM develops, the sac wall breaks and CPM get out of the sac. Finally,the cells of CPM disperse into the connective tissue surroundings. There are otherkind of quasi-cell-polymerized-mass(QCPM) distributed over the marginal mantle.The process of cytogenisis and development of QCPM are observed and are compar-ed with OPM, and indicate that QCPM made the formation of both histocyte andhisto--structure of the connective tissue of the marginal mantle. As the CPM develops, some different cells such as fibroblastes and granule cellsare formed. The transformation between these two kinds of cells are constantly occu-rred: fibroblasts gradually accumulate the granule slime uacuoles and finally developinto spherelike granule cells. Sphere-Like granute cell revert to the original stateafter the slime vacuoles were released. Therefore, as the new connective tissue for-med from the developments of the CPM or QCPM, two kinds of secretory materialare produced, ie. fibrous material and granule slime vacuoles, the former constitutesthe fundamentals of the connective tissue while the latter is related to the formationof the shell.