To seize the aspect of microinvasive carcinoma in relation to C.I.S., graphic reconstruction of 37 cases, comprising 31 cases of Stage Ia and 6 cases with confluent invasion to a depth of 5mm or less, were represented in detailed schematic drawings. From a new approach to analysis, the following conclusions could be drawn. Only 1/37 cases (2.7%) revealed the transition from C.I.S. to Stage Ia. Configurations of the remaining 36 cases were quite different from those of C.I.S. Their distinctive features were represented in transversal linear spread, parallel to the S.C.J. line. Their extent and multiple foci regulated ramified lesions. According to the degree of ramification, 36 cases were divided into zonal type (33 cases) and multiple type (3). Inceptive foci of invasion from glandular involvement were noticed in 28/33 cases (84.8%). In 17/33 cases (51.5%), lesions were limited to the columnar epithelia region. They provided evidence of the origin of a sub-opening cleft area. The ratio of numbers of early stromal invasion to those of glandular involvement indicated the speed of progression. Early stromal invasion from surface epithelial lesion was discernible in 9/33 cases (27.3%). In the 5 cases without any early stromal invasion from glandular involvement, they might originate from surface epithelia.