The Snuggling Blastocyst
Michelle Malkin believes Henry Waxman is waging war on abstinence education. In support of her belief, she points us to John Bambenek's quick takedown of the report. The takedown raises four objections, two of them being:
Of course, Ms. Malkin is a writer, so a basic knowledge of biology is apparently not a necessity for her. However, there's no need for you to be in the dark. I'll address the "when life begins" topic in a separate post, so let's focus on implantation today.
Implantation is the burrowing of the blastocyst into the uterine lining (the endometrium). What is a blastocyst? It's a bunch of cells with some fluid between them. Initially, you have a mature egg + sperm = a zygote. The zygote cleaves, and the resulting cells are called blastomeres. As the blastomeres continue to divide, they produce a solid, mulberry-like ball of cells. A 16-cell ball is called a morula.
The morula enters the uterine cavity approximately 3 days after fertilization, and floats around in the cavity for a few more days. During this time, fluid gradually accumulates between the morula's cells, and, once a fluid-filled cavity is formed, the morula becomes a blastocyst. There are about 107 to 256 cells in a blastocyst. The blastocyst begins to implant about 6 days after fertilization.
Blastocysts do not snuggle; they burrow into the uterus. This is not nit-picking ... I say burrowing, you say snuggling. Describing implantation as snuggling is incorrect.
Implantation is an extremely aggressive process, involving the destruction of maternal tissue. First, the blastocyst sticks to the uterine wall, and gradually erodes the uterine lining. It does that by secreting substances that destroy the matrix keeping the uterine cells together. Then it invades those empty spaces, in between the uterine cells.
The processes used by the blastocyst to implant are indistinguishable from those used by metastasizing (spreading) cancer cells.
[Just to be clear. I'm not a writer, so what I wrote above is not a fancy description of implantation, or a value judgment. It's a more or less direct* quote from the scientists who actually observed the process.]
Moreover, once inside, the blastocyst invades the mother's blood vessels, and destroys the walls of these vessels. [This process is essential for establishing an uteroplacental blood flow.]
In fact, because the tissue involved in implantation is so aggressive, if something goes wrong with the mechanism that normally limits its invasive growth, the blastocyst can "snuggle" [WARNING, graphic picture] a hole right through the uterus (or, for that matter, through any organ its cells happen to seed.]
Returning to the topic of abstinence education, granted, there's no expectation of an in-depth discussion of reproductive biology in a general sex-ed class. However, a minimum of scientific accuracy should be expected. Hence, anyone with a basic knowledge of biology will take issue with describing implantation as a "snuggling" of the blastocyst, since it's a false description; it contradicts reality.
Let me end with an interesting aside. The uterine tissue is not essential for implantation. The blastocyst can implant in the fallopian tube, ovary, spleen, and even the testicle (this was done in experimental studies, of course). So, gentlemen, pay attention, for soon it might be possible for you to carry a pregnancy to term in your scrotum. [OK, you men can stop hyperventilating now. I'm exaggerating for effect.]
* The actual quote is:
These functions of cytotrophoblasts [a layer of cells in blastocysts] invading the endometrium [the lining of the uterus] are indistinguishable from those of metastasizing malignant [cancer] cells.
Williams Obstetrics, 21 ed., p 89