Page 812 - Atlas of Histology with Functional Correlations

The principal cells in the ductus epididymis are lined with long

microvilli, or stereocilia, that absorb testicular fluid that was not absorbed in
the ductuli efferentes during sperm passage from the testes. In addition, the
principal cells phagocytose abnormal or degenerating sperm cells and
residual bodies that were not removed by the Sertoli cells in the seminiferous
tubules. The principal cells in the ductus epididymis also produce a

glycolipid decapacitation factor that binds to the surface of the sperm
membrane. Decapacitation factor inhibits capacitation, or the fertilizing
ability of the sperm, until the sperm are deposited into the female

reproductive tract and this factor is removed.

The sperm are activated within the female reproductive tract by a process
called capacitation. This action increases the sperm’s affinity for fertilizing
an oocyte by allowing the sperm to bind with sperm receptors on the zona
pellucida of the ovulated oocyte. This produces an acrosomal reaction that

releases the acrosomal enzymes, which disperse the cells that surround the
ovulated oocyte, digest and penetrate the zona pellucida around the oocyte,
and fertilize the ovum.

Summary

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