Reference for Niddah 53:7

מעשה ותלו את השליא בולד עד כ"ג ימים

Rabbah b. Shila citing R. Mattena who had it from Samuel stated: It once happened that a placenta was attributed to an embryo as late as<span class="x" onmousemove="('comment',' Lit., 'until'. ');">⁶</span>

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