> 
Thanks Jean, I think you have made an excellent and concise summary of
currently accepted principles in regard to milk supply. Your comments
regarding advice to women suffering problems associated with oversupply are
also very important. It is essential to address these issues for women when
they arise.

I would however like to suggest that based on what we know of breast anatomy
(or probably more precisely what we don¹t know) I don¹t think we can assume
because a women has a larger sized breast that she will have a more
extensive ductal system to carry the milk. Someone may correct me on this
but I'm not aware of any research that tells us how glandular tissue is
distributed within the breast in regard to - if you have a larger breast
most of the alveoli will be be situated at the very back of the breast which
would necessitate "longer tubes". It's possible that large breasted women
may predominantly have most of their milk producing tissue in the middle of
the breast or at the front or in a combination of all three.  It may also
vary widely between breasts and between individuals. The thing is we just
don¹t know.

Just as an example of how much we don¹t know - Donna Ramsay who is the
ultrasonographer conducting research into let down, ductal size and
placements etc told me she has in one of her mothers isolated a duct (using
ultrasound) that appears to initiate in a certain part of the breast and
found that it meanders over to the other side of the breast and comes back
again before draining into a nipple pore. I for one have always visualised
this very neat diagrammatic arrangement that we see so often depicted - of
the alveoli, grouping into lobules and draining straight to the nipple. I
believe the morphology that we currently base our knowledge on was done on
cadavers a very long time ago. It's probably time we started to review this
"knowledge". Certainly this finding of Donna's has made me think a little
differently about duct placement and perhaps for some women may provide a
clue as to why they experience repeated blockages in specific areas.

Rachel reported:
>In the course I took on maternal-child nutrition in 1979 at University of
>Washington, our teacher, Bonnie Worthington, said that only 20% of the milk
>drunk at a meal was actually in the breast already and the rest was
>synthesized during suckling and drunk as it was produced.

Rachel, I'm not aware of the research that this was based on but the
research done recently does not support these findings. For example:
 "It has been shown that on average, over a 24 hour period, infants only
removed 76% of available milk at a breastfeed and the breast can rapidly
change the rate of milk synthesis from one interfeed interval to the next"

Daly, SEJ; Kent JC; Owens RA & Hartmann PE. 1996 Frequency and degree of
milk removal and short term control of human milk synthesis. Exploratory
Physiology 81:861-75

There is also a couple of excellent papers by Stephen Daly and Peter
Hartmann in JHL 1995. 11:pp20 (? Not sure of the first page) to 37.
Infant Demand and Milk Supply. Part I & II.

For those interested in extended lactation:
Kent JC, Mitoulis L, Cox DB, Owens and Hartmann. Breast Volume and milk
production during extended lactation in women. Experimental Physiology. 84:
435 -47.


Regards
Cathy Fetherston CM MSc IBCLC
Perth Western Australia

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