Now another unique thing with the equids is, and, and you know, don't see this in a
lot other species is, that they get this
endometrial cup formation between day 25 and day 35.
And it's really, really important because this is
again, you know, trying to, you know, the normal
process of a pregnancy in the equids and if
anything goes wrong here, then they lose the pregnancy.
And we see most of our pregnancy losses, you know, about day 40 and before.
So, you know, if you looked at a young mare, the
research has shown, you know a mare between three and eight years
old, as soon as you detect a pregnancy on day 14, about
82%, a little less than 82% of those will carry to term.
So you'll lose about 18% of those pregnancies in those young mares.
And we see most of that happening when all of these important processes are going on.
So, before day forty.
So these cups form.
And I'm going to show you some pictures of
these, and they are important because they secrete this
hormone, we call it eCG or equine chorionic
gonadotropin, and it's really, really critical in maintaining pregnancy.
So you can see in this, this early embryo, because this is still an embryo.
It's before day forty.
And it forms these girdle cells and it's
a discontinuous ring, so you can see it here,
and then up around here, you know, that discontinuous
ring that kind of forms all the way around it.
And for those that are Star Wars fans, I'm showing my age, I always say it
looks like the Death Star, because you have
this circle around, you know, with the embryo.
And again they're, they secrete this, this
equine chorionic gonadotropin, and it acts like LH.
So if we go back to our estrous cycle, we
still remember when progesterone is high we still have FSH circulating.
So we're still having follicles develop, and that's normal for the horse.
You know, progesterone's high, that's going on.
Well what this ECG does is, it acts like a luteinizing hormone and it causes these
follicles to either ovulate or luteinize and it secretes more progesterone.
So it's really important to maintaining pregnancy.
And then this continues 'til about, you
know, mid-gestation, day 180, when the, the fetal
gonads and the placenta take over and the,
the ovaries are done, you know maintaining pregnancy.
So if you looked at all the hormones, so we're
talking this process happening here, and here you can see eCG.
So as that spikes, you can see, progesterone goes
down a little bit, and then goes way back up.
So that's what's going on during this
process is, you're getting those endometrial cups forming,
signaling to the mare, produce more progesterone, so
her ovaries respond and then she maintains pregnancy.
Now, what's not on this graph, you know, yeah
you have estrogens here, but you have these progesterones, or
what we call pregnanes that would spike there, that
pretty much take over on maintaining pregnancy for the horse.
And the dog.
So, the official placenta doesn't really
start forming until later, around day forty.
You know, so endimetrial cups form before
then and then you have the placenta forming.
So, you know, that, that early embryo still dependent, or that
early fetus, still dependent on those
nutrients being secreted by the endometrium.
Now this lasts until about day 120 and then
you can see in this image, you know, the placenta
grows up, grows up and out into both horns
and the uterine body, where it houses that young fetus.
And if you are not really aware of it, the placenta is, it's organ in its own right.
It's made up of a bunch of cells.
They need oxygen.
They need nutrients.
So, they actually get first shot at Mom's
blood that they're, they're taking in, Mom's nutrients.
And then they pass whatever's left over to the fetus, so, you know,
the placenta is, is, is, is, is a pretty dynamic organ in itself.
Pretty cool.
Pretty cool stuff.
