When young sperm are not just sperm anymore

You know that in your first hours of life, cells in the nascent embryo mature into skin, heart, gut, or any type of cell - called totipotency.

New research shows that that totipotency is a step-wise process, manifesting as early as in precursors to sperm - called adult germline stem cells (AGSCs) which reside in the testicles.

Typically, sperm precursors live a mundane life.

They divide, making more cells like themselves, until they receive the signal instructing them to mature into sperm.

There is evidence now that these cells have the potential to do more.

"Under the unusual conditions that promote the cells to form dense cancerous masses called testicular teratomas, the young sperm transform into precursors of skin, muscle and gut cells," said Bradley Cairns, a professor of oncological sciences at University of Utah.

This prompted the investigators to examine the gene programme within sperm precursors.

They wondered, would it be like that of a cell that is destined to become a single cell type, or like that of a cell with the potential to become anything?

The answer, they found, is that the sperm precursors are somewhere in between.

In other words, these young sperm have the potential to become totipotent.

Once fertilisation occurs, Cairns explains, cells have to become fully totipotent in a short amount of time.

"Then, when the sperm and egg come together, all you have to do is complete the job that you had already started," he added.

The research was published in the journal Cell Stem Cell.