So…the end of the weekend. I spent almost every moment of it studying or sleeping. It wasn’t all that fun.
Tonight there was a review session for the bio exam. I usually hate it when people say things like this, but I am going to say it – this test is on what seems to be an insane amount of material. It is covering big topics, in a *lot* of detail, and some of the topics have absolutely NOTHING to do with each other. See: immune system, and hormones (ok, those are similar enough), and kidneys and not being cold or hot (ok, those are close enough), and…evolution. (Huh?) And then back to…embryos. Specifically, like, fertilization and the first oh, say, 10 cell divisions of an embryo (zygote). In humans, birds, frogs, and…sea urchins. Yeah, sea urchins. So vitally important to know how *they* start out.
But in any case, so we get to learn about sperm and eggs and how they find each other and set up shop. Great. Well, one of the (many) things we need to know about is what is called the “fast block” to polyspermy (mulitple sperm going into the egg) (ie, preventing that from happening) and the “slow block” to polyspermy. The fast block is something that sea urchins have, because their eggs are floating everywhere and surrounded by sperm everywhere and they need to be sure to only have one sperm get in that egg, right? And the slow block is something that *everyone* – mammals, sea urchins, frogs, you, me…has. (The fast block happens…faster…than the slow block. As the name might imply.)
See where I’m going with this?
So I have learned all of the blocking polyspermy stuff. I feel rather up-to-speed on these things, if only because hey – it is relevant to me (see previous post re: toaster magic, and peeing), and it was interesting. It came up today in the review.
Volunteer former student running the review session: “So the fast block is… and the slow block is… and they are in all animals”.
Dude in the class: “Wait, I thought the fast block wasn’t in mammals?”
Volunteer dude running session: “It isn’t? [Fumble.] Hmm…”
Another dude in the class: “So few sperm get to the mammal egg that they don’t NEED the fast block…by the time you need to block the sperm, the slow block is in place.”
(Me…thinking about how I WISHED mammals had a fast block and a slow block.)
(Some ensuing discussion about whether mammals had fast blocks or not, and why polyspermy is a Bad Thing.)
Someone in the room: “Because what a MESS it would be if there were more than one sperm in the egg!!”
Everyone…laughs. All I was thinking was, “It’s not that funny when it actually happens…” I was just short of breaking down, thinking about what a MESS our kid was.
Yes, that’s exactly how I think of him. A mess.
Anyway, part of me thinks I am being too sensitive. (A big part.) But the other part? Wishes that mammals really DID evolve with both the fast block and slow block, because then I bet we wouldn’t have had the eager-beaver sperm problem. Damn sperm.
Damn ineffective slow block.
And…back to studying. Some more.