Thanks Jean for your well considered reply to my comments and thoughts -
just wanted to briefly respond to a couple of things
> "Lobule" is the histological name of the smallest clusters of alveoli
> plus their collection area. This newly secreted milk must exit through a
> very tiny ductule, the first tube off of the lobule, leading into the
> collecting ducts.
>
> The tininess of the ductule, I think, is the reason the skim milk can
> trickle on through it, but the largeness and generally spherical shape of
> the fat globules requires the force of the MER to change their shape
> enough to force them through the ductules to the collecting ducts.) But
> this, too, would then have a shorter distance to go before reaching the
> nipple in a B cup breast
Alveoli are about 100 -200 microns and fat globules are around 2-3 microns
in size - the ductules exiting the alveoli easily accommodate the fat
globules so I donšt think we should think of them having to change shape or
be forced through - although there is certainly a filtration effect during
drainage from the alveoli where the aqueous component of milk will drain
more quickly into the ductules than the bigger molecules such as fat, cells
and casein micelles - and certainly MER will expedite the movement of the
larger molecules and cells.
>Let's say someone with a B cup has 20 lobes in each breast. That would
>probably mean 20 ducts joining into about 10 milk sinuses, with 10 holes
>in the nipple. (I believe this convergence of ducts is something emerging
>from Donna's ultrasound research with Dr. Hartmann.) This mother would
>have a large storage capacity, but in 20 different shorter ducts.
Donna is only able to isolate ducts 1.5mm or larger in diameter on
ultrasound so has not been able to trace the ducts back to the lobular
systems. Although I think in one women she has seen a duct this size go back
almost as far as the chest wall. The ductal branching she has been
commenting on is very close to the nipple/areola area.
>"Consequently it is not surprising to find that the amount of milk that
>potentially can be stored increases with breast size. Indeed, although we
>were not able to quantify the relationship, we observed that the
>measured storage capacity of a breast increased with breast size." (p.
>32.)
>"Infant Demand and Milk Supply. Part 2: The Short-term Control of Milk
>Synthesis in Lactating Women", Steven E.J. Daly, PhD and Peter E.
>Hartmann PhD, J Hum Lact 11 (1) 1995 , p. 27-37.
Later work by Jackie Kent et al. (extended lactation paper, 1999) and David
Cox et al. (Breast growth paper,1999) has refuted this and found that
"storage capacity was independent of breast size" (Cox, p432). Full
references given in previous posts.
Warm regards
Cathy Fetherston RM MSc IBCLC
Western Australia
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