INSL6

Where it comes from

Made in

Germ cells of the testis, spermatocytes and spermatids

Sent out by

Within the seminiferous tubule

Acts on

• Developing sperm, presumably

What it does

• Found in the human and rat testis and made by male germ cells, switching on as the first wave of sperm production reaches the pachytene stage ¹
• Mice without it arrest sperm development in late meiotic prophase, lose most of their mature sperm, and the majority of males are subfertile ²
• After muscle injury it is induced in the damaged muscle and acts there as a regenerative factor, again in mice ³

In medicine

• Nothing in people: no assay in care, no disease firmly tied to it, nothing given
• Its place in human fertility is untested, and with no receptor known there is no way to probe it directly ¹

Beyond the body’s own use

• The open question is whether the mouse result carries across. Human INSL6 variants have not been linked to infertility, and the peptide has never been given to anyone
• The muscle finding has drawn separate interest in regeneration, still only in animals ³