How do transcriptionally inert spermatids differentiate into spermatozoa?
Spermatids are spherical cells with centrally located nuclei. How are they transformed into functional spermatozoa? The morphological events during spermiogenesis are discussed in your textbook, and you should read them carefully. We shall focus here on nuclear modifications and their consequences. The major events in nuclear modification are: chromatin condensation and morphological changes. Chromatin condensation helps to streamline the cell by reducing volume. It also may serve a protective function, reducing the susceptibility of the DNA to mutation or physical damage. Condensation is facilitated by formation of specific DNA-protein complexes. Proteins that may be involved include protamines (small, highly basic, arginine-rich proteins), histone-like proteins or other sperm-specific proteins. Replacement may be gradual, with somatic histones being replaced by sperm-specific proteins, or it may involve discrete steps in which transitional proteins interact with the DNA after the his
