uterine milk

deinonychus commented on the word uterine milk

"In sharks and rays, the term ovoviviparity has recently been deprecated in favor of aplacental viviparity. Authors may regard the two terms as synonymous, or equate ovoviviparity only with aplacental yolk-sac viviparity, in which the embryos are solely sustained by yolk (as opposed to secondary provisioning by their mother in the form of 'uterine milk', such as in the stingrays, or unfertilized eggs, such as in the mackerel sharks; the latter is referred to as intrauterine oophagy).

There is a wide range of forms of intrauterine provisioning however, which could complicate the classification. In at least some sharks the routine intrauterine oophagy is not limited to unfertilised or trophic eggs, in various forms and in in some the principle extends to actual intrauterine cannibalism."

(Wikipedia)

September 26, 2012