Galena is
one-third through gestation – yes, ALREADY!
We’ve been
so caught up with getting Topaz’s breeding accomplished that we’ve hardly had
head-space for Galena’s progress, but it goes quickly when gestation is only
nine weeks long. I’m not sure where these first three weeks have gone!
Puppy
development starts quite slowly. The eggs are released on the day of ovulation
(duh) and take two days to “ripen” so that fertilization can occur. That’s why
we wait until two days post-ovulation to breed, especially when doing
artificial insemination, as the fresh-chilled sperm don’t last as long as the
sperm in a natural mating.
Once
breeding has taken place, it apparently takes another couple days for the sperm
to get to and fertilize the egg, and another several days for the fertilized
ova to reach the uterus where they will attach to the uterine wall. During that
period the egg begins to divide – again this begins slowly. Three days post
fertilization is when the first division, into two cells, occurs. A day later it’s
four cells, then another day to get to eight cells (total of three divisions).
By day 7 the ovum it’s still only at the fourth division (16 cells). During the
second week it divides only twice more, to reach 64 cells and form the morula
(early stage embryo of as yet undifferentiated cells) and find a place in the
uterine wall to embed itself. By the end of the second week, the cells begin to
differentiate, at first only into an outer shell and inner cell mass. During
the third week the placentas are formed and development of the basic structure
of the puppy begins in earnest. With the power of exponential growth, those 64
cells present at the edn of week two have formed over a thousand cells by the
end of week three, and the beginnings of the nervous system are in place. At 20
days the ovules have finally changed shape, elongating to begin to form a
puppy.
