At embryonic stages 8-9 CycE transcript is expressed in three columns of neuroblasts per segment, forming a series of segmentally repeated stripes.

CycE transcripts disappear from the cells of the dorsal epidermis just before they go through their final division (mitosis 16). They are present in the region of the dorsal epidermis that goes through an extra division and disappear during additional cycle 17. CycE transcripts are present in the proliferating cells of the CNS and PNS. They are also observed in endoreplicating tissues.

Type 1 CycE transcripts are first detected after cellularization in a striped pattern along the anterior-posterior axis of the embryo. During gastrulation, high levels of CycE transcripts are seen in the neurectoderm. Expression is seen in the primary neuroblasts as they delaminate from the ectoderm. During germ band extension, a dynamic pattern of staining is seen in the CNS and PNS. Later expression occurs in cells of the ventral nerve cord and in the proliferative centers of the brain lobes. This pattern is consistent with the pattern of proliferation of neural cells in the CNS.

Type 2 CycE transcripts are expressed at the earliest stage where embryos are undergoing rapid nuclear divisions in a syncytium (0-2hrs). At the stage of pole cell formation, transcripts are more concentrated at the posterior pole where the pole cells are forming.

Expression intensity of CycE varies as the cell cycle progresses, with greatest intensity found in the latter part of phase G2.

CycE protein is present throughout the early embryonic cycles. It is predominantly nuclear during interphase and becomes dispersed in the cytoplasm during mitosis. Two types of CycE protein are observed by immunoblotting. The form with the lower mobility is maximal during mitosis. The higher mobility form is abundant in G₂ and is nearly absent during M and early S phases.

High levels of CycE protein are detected in histoblasts in third instar larvae before histoblasts initiate divisions. Stored CycE declines progressively during the first cell cycles and is depleted by the third prepupal cycle a 4hr APF.

CycE protein is expressed at varying levels (suggesting cycling) in both nurse cells and follicle cells. Within individual egg chambers, nurse cell nuclei with high, intermediate or low (to undetectable) levels of CycE protein are observed. Levels are always high in the germinal vesicle and increase as egg chambers develop.

CycE protein is present in embryos in mitotically proliferating and endoreplicating cells. In larval optic lobes, the pattern of CycE protein expression is similar to the pattern of S phases. It is present in the outer optic anlage, the inner optic anlage, and in a band corresponding to the S phase lamina precursor cells. It is absent in G₁ phase lamina precursor cells. It is also present in a region of the lamina where only a portion of the cells are in S phase. In the eye imaginal disc, CycE protein is present in a subset of the asynchronously proliferating cells and in a band of cells just posterior to the morphogenetic furrow that are in S phase but not in G₁ cells within and anterior to the furrow. In summary, CycE protein is absent in G₁ phase cells but appears at the onset of S phase in proliferating cells of the larval optic lobe and eye imaginal disc.