Translational regulation is seen in several of these steps. The products of meiotic divisions are connected by cytoplasmic connections. The functions of these connections may differ between those cells producing sperm and those producing eggs. 19.7 Gene expression during spermatogenesis. Transcription occurs both from the diploid spermatocyte nucleus and from the haploid spermatid nuclei.
Posttranscriptional control is also important in regulating sperm gene expression.
Sperm mitochondria are often highly modified to fit the streamlined cell. The mitochondria of flies fuse together to form a structure called the Nebenkern, and this fusion is controlled by the fuzzy onions gene. 19.9 Hormonal control of yolk production. Vitellogenesis in amphibians is mediated primarily by estrogen. Estrogen instructs the liver to express and secrete vitellogenin, and this protein is absorbed from the blood by the young oocyte.