Basics: Guest Post 3: Sperm maturation and ejaculation

What you all were waiting for has finally come! Yeah.
Sperm maturation and ejaculation
OK!! So the last time I was over here at Neurotopia we were talking about sperm in their infancy. We discussed spermatogenesis — how we got from a diploid spermatogonial stem cell to a haploid spermatid — and then spermiogenesis — the process by which the spermatids acquire the features of spermatozoa: tails, acrosomes and the like.
We stopped there when the sperm had just graduated from diapers to their big kid undies, and we’ll pick up where we left off.

Continue reading

Friday Weird Science: the swimming of the sperm

Sci will admit that the sperm paper she picked for this week really is an excuse to use this image:
michael phelps sperm.png
(heeheehee)
But really, sperm swimming is an important questions in terms of fertility. An ovum is only viable for about 24 hours, and a female only produces one per month. Sperm are viable for a little longer than that, but still, timing is rough. And once you get past the timing, you get into sperm getting lost, sperm swimming in circles, sperm getting stuck in the vaginal mucosa, and sperm getting to the egg only to be thwarted by the zona pellucida and corona radiata (the corona radiata is a group of cells surrounding the egg, while the zona pellucida is a tough, thick protein lattice on the outside of the egg, inside the corona radiata. Tough barriers).
sperm shapes.png
(Who’s betting on the double-headed one?!)
So when it comes down to it, it takes more than a straight swimmer to make it to the egg. But what, exactly, does it take?
ResearchBlogging.org Force, et al. “Membrane fluidity and lipid content of human spermatozoa selected by swim-up method”. International Journal of Andrology, 2001.

Continue reading

Friday Weird Science: Scooping Semen

I owe this entry to Scientific American, where they have a great article up on this very subject. Imitation being the most sincere form of flattery, I’m getting me some of this action! Jesse Bering has an excellent write up over there, far more in depth than mine, but I flatter myself that mine has better pictures.
And it’s a great subject. I mean, we all probably know, deep down (or not so deep down), that penises are some funny looking things. All bulbous at the top and weird. You know it’s true. But what if the penis was shaped all funny…for a reason?
ResearchBlogging.org Gallup, GG. “The human penis as a semen displacement device.” Evolution and Human Behavior, 2003.
(WARNING: pictures of penises below the fold. Mostly not human, but you’re still warned.)
And the best thing about this paper, it’s another example of those not afraid to develop a coital simulator in the name of SCIENCE!
And this is a great theme for the First of May (NSFW, like everything else in this post…):

Continue reading