My understanding
>is that the fat globules cling to the inside of the aveolar cells.

Actually they are outside the cells, but inside the lumen of the alveolus.

 With
>release of oxytocin the cells squeeze and push the fat cells out into the
>ducts.  Breast compression possibly helps with stripping the fat out of
>these cells.  It does increase volume taken with very little work on baby's
>part. Foremilk is present in the sinuses when feeding starts.  Let down
>causes the fat to move into the ducts and more milk is produced while baby
>is nursing.  There are probably many little let downs that aren't even
>perceived by mom, that keep pushing fat cells out. I think I've read that
>approximately 30 % of milk is present when baby starts to feed and more is
>made "on demand".

I'm not sure where this idea of most of the milk for a feed being suddenly
produced during the feeding time came from. Perhaps from the old idea that
it was just the prolactin stimulation that resulted in a sudden surge of
milk production? In actual fact, the breast is *continually making milk*,
the rate being determined at any one point in time by the degree of breast
emptiness. Nearly all the milk available to a baby at one feed was there
before he started. Synthesis continues, of course, during the time he is
sucking, but not at a particularly increased rate, at least not until the
breast partially empties, the inhibitor level drops (autocrine control) and
the breast responds by increasing the synthesis rate. This actual change in
rate depends a lot on how much the baby actually takes. Babies almost never
take all the milk available - they stop when they have had enough. The
resulting changed synthesis rate will depend on how much has been left
behind. The less left behind, the greater the increase in synthesis rate.

This also explains why the two breasts can have vastly differing synthesis
rates and supply - each is controlled by the inhibitors in the milk. If
hormones (like prolactin) were entirely responsible for milk production,
they would both be the same, as endocrine systems work via the bloodstream
and go everywhere.

I hope I have been able to explain this well enough.

BTW, Heather Welford Neil's description of the sponge analogy is really
very good. What she wrote about what happens in the breast sounds correct
to me.

******************************************************************
Joy Anderson B.Sc. Dip.Ed. Grad.Dip.Med.Tech. IBCLC
Nursing Mothers' Association of Australia Breastfeeding Counsellor
Perth, Western Australia.   mailto:[log in to unmask]
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