Tag Archives: sex

Having sex to become pregnant: Why it is necessary?

15 Aug

The gorgeous plumes of a peacock are a classic example of a trait that emerged solely for sex appeal.

“Some are fancy on the outside.  Some are fancy on the inside.  Everybody’s fancy.  Everybody’s fine.  Your body’s fancy, and so is mine.”  –Fred Rogers (♫ listen here)

“Some mollusks (not many) can have children merely by sitting around and thinking about it.”   — E.B. White, Is Sex Really Necessary?

As it turns out, snail sex (a snail is a type of mollusk) is really far out:  Some can self-fertilize, some stab their mates during foreplay with harpoon-like “love darts,” and most snails have two sex organs, so they can do it both ways at the same time.  As E. B. White observed, “mollusks are infinitely varied in their loves, their hates and their predilections.”  See snails doing it!

Scrambled eggs, mutant sperm

4 Oct

MEIOSIS: A cell with 46 chromosomes becomes four sperm, each with 23 chromosomes. Shown here, the "Chromosome 1" pair (top left) gets duplicated, shuffled, and divided into sperm cells (bottom).

In other posts, we’ve discussed meiosis and mitosis, the two little cellular dances that need to be considered on the way to a basic understanding of genetics.

Meiosis affords genes the opportunity to recombine.  Mitosis affords genes the opportunity to replicate, and replication gives genes the opportunity to mutate.

Both processes are involved in the production of eggs and sperm, but eggs recombine more than sperm, and sperm replicate more than eggs.  Hence the title of this post, in which we will describe how sperm and eggs are made inside of the testicles and ovaries of two randomly chosen celebrities.

Spermatogenesis

Bob Saget’s body will, over his lifetime, create billions of sperm.  Right now, inside of his testes, the sperm-making factory is running. (We invoke Bob Saget here as an example; we could have chosen any person with testicles.)

Inside of Bob Saget’s testicles are little tubes that are lined with spermatogonia, the germ cells that can divide and develop into sperm.  These cells proliferate through a process called mitosis, where one cell divides into two cells, each with the same set of chromosomes as the original. Continue reading