"wouldn't that mean that letdown only occurs after oxytocin wears off?"

Because there's never been any real *need* to break an MER into smaller components, we don't generally do it.  But there's a whole chain of events and locations:  prior production of oxytocin (OT) in the hypothalamus, prior delivery of OT to the posterior pituitary, prior storage in the posterior pituitary, emission from the posterior pituitary (the start of an MER), OT traveling to certain parts of the brain as a neurotransmitter, OT getting into the blood stream, traveling to the breasts, hitting the receptors there, alveoli contracting in response, milk squeezing out of the alveoli and down the ducts and out the nipple, milk or swallowing becoming visible.  

All we've ever really focused on is the tingle in the breasts and the milk/swallowing.  But I'm quite sure that what we're "seeing" with the D-MER mothers is the neurotransmitter part of the sequence, and that would begin - unfelt by the majority of us - before the breast involvement can begin, just because the OT is going to spread via nerves within the brain faster than it's going to get through our relatively sluggish circulatory system to our breasts.

But all of the above is just an ignorant LC's rough understanding, readily changed by additional knowledge!!

Diane Wiessinger, MS, IBCLC, LLLL  Ithaca, NY  USA
www.normalfed.com

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