Practice question

Human oocyte centrioles degenerate during oogenesis, leaving mature egg lacking functional centrosome. Fertilizing sperm introduces proximal centriole, often with atypical structure, which recruits maternal pericentriolar material to reconstitute active centrosome in zygote. This centrosome nucleates microtubules and organizes first mitotic spindle, ensuring accurate segregation of parental genomes during cleavage. Mitochondria, ribosomes, Golgi and endoplasmic reticulum are predominantly maternal due to oocyte cytoplasmic abundance and active degradation of paternal mitochondria via ubiquitin-proteasome and autophagy, establishing maternal inheritance pattern for mitochondrial DNA and ooplasm.