Specialized follicle cells also make the micropyle, the egg's terminal structure through which sperm pass into the egg. Mature eggs ovulate one at a time and pass into the uterus. Once mated, females are able to release stored sperm from their seminal receptacles. Sperm enter the micropyle while the egg is still in the uterus. The first meiotic division has begun and is still in progress when fertilization and ovulation occur.
Males contribute more than just DNA to the zygote.
The zygotic centrosomes, essential for cell division, are derived from the male. For information about the establishment of oocyte axes, messenger RNA localization in the oocyte, and the basis of polarity in the developing embryo, see posterior group genes, anterior group genes, dorsal group genes and terminal genes mRNA localization and translational control during oogenesis RNA localization is often combined with local translational control. This allows simultaneous spatial and temporal control of protein synthesis within a particular region of the cell. In the case of neurons it is speculated that localized mRNAs may be regulated translationally in response to synaptic activity. The combination of translational control with RNA localization can also serve to restrict protein activities to defined regions in the cytoplasm, thereby preventing deleterious interactions from occurring elsewhere in the cell.