In which we inform you that the term "sneaker sperm" does not mean what you probably thought it does: And we suspect that you'll be happy to hear it. In this case, "sneaker" refers to the mating style of a male squid. Female squid find large males appealing enough that they allow them to transfer sperm directly to the place where the females store it. Small squid, in contrast, tend to just glop a packet of sperm onto a female's exterior in the right general area (which, unfortunately for the female squid, is right near the mouth).
All of this seems to have exerted some evolutionary pressure on the size of sperm. The weird thing (well, one of the weird things) is that the authors can't figure out why. They suggest that it has something to do with the difference between the internal and external environments where the sperm ends up, but they haven't yet managed to test this.
As if scientists aren't anal enough already: You'd think the title of this one about says it all: "Successful Implantation of Bioengineered, Intrinsically Innervated, Human Internal Anal Sphincter." And yet we here at Weird Science find that there are still things to say. For starters, these sphincters weren't entirely human; instead, they were a hybrid of human muscle cells (isolated from actual sphincter tissue—ouch) and nerve cells from a mouse. Not just any mouse, mind you, but a specific, genetically engineered strain that's marketed under the trade name "Immortomouse."
The replacement sphincters were grown in culture for a bit, and then implanted under the skin of mice for a few weeks. Even though they had nothing to retain in this position, they established a blood supply and exhibited normal responses to various stimuli. The researchers hope this is the first step toward engineering useful replacement tissue for those who are no longer retentive.
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