<P> Spermatids are connected by cytoplasmic material and have superfluous cytoplasmic material around their nuclei . </P> <P> When formed, early round spermatids must undergo further maturational events to develop into spermatozoa, a process termed spermiogenesis (also termed spermeteliosis). </P> <P> The spermatids begin to grow a living thread, develop a thickened mid-piece where the mitochondria become localised, and form an acrosome . Spermatid DNA also undergoes packaging, becoming highly condensed . The DNA is packaged firstly with specific nuclear basic proteins, which are subsequently replaced with protamines during spermatid elongation . The resultant tightly packed chromatin is transcriptionally inactive . </P> <P> In 2016 scientists at Nanjing Medical University claimed they had produced cells resembling mouse spermatids artificially from stem cells . They injected these spermatids into mouse eggs and produced pups . </P>

Name the term used in metamorphosis of spermatids