לֹא־נִכְחַ֥ד עָצְמִ֗י מִ֫מֶּ֥ךָּ אֲשֶׁר־עֻשֵּׂ֥יתִי בַסֵּ֑תֶר רֻ֝קַּ֗מְתִּי בְּֽתַחְתִּיּ֥וֹת אָֽרֶץ׃
Os meus ossos não te foram encobertos, quando no oculto fui formado, e esmeradamente tecido nas profundezas da terra.
Mishnah Keritot
Some women [after childbirth] bring an offering which is eaten; some bring one which is not eaten, and some bring no offering at all. These bring an offering which is eaten: If a woman miscarries a fetus which has the shape of beast, or a wild animal or a bird, the words of Rabbi Meir; but the sages say: only if it has a human shape. Or if a woman miscarries a sandal-like fetus or a placenta or a fully formed fetus, or one that comes out in pieces. Similarly, if a female slave miscarries, she brings an offering which is eaten.
Mishnah Bekhorot
There is one who is [counted as] a firstborn [with respect to] inheritance but not with respect to redemption from a priest; a firstborn with respect to redemption from a priest but not a firstborn [with respect] to inheritance; a firstborn [with respect to both] inheritance and redemption from a priest; and a firstborn [in respect] to neither inheritance nor redemption from a priest. Which is a firstborn [with respect] to inheritance but not to redemption from a priest? One which follows one which was not viable whose head came forth alive, or one born in the ninth month whose head came out dead, or when a woman aborts something that looks like an animal, beast or bird, the words of Rabbi Meir. But the sages say: [it is not considered an opening of the womb] until [the abortion] has the form of a human being. If [a woman] aborts a sandal or a placenta or a fetus having an articulated shape, or if an embryo came out by pieces, [the infant] which follows after them is a first-born [with respect] to inheritance but not a first-born for redemption from a priest. If one who never had children married a woman who had already given birth, even if she had given birth when she was a slave but is now free, or [had given birth] when she was a non-Jew but has since converted, if after coming to the Israelite she gave birth, [the infant] is considered a first-born [with respect] to inheritance but not a first-born for redemption from a priest. Rabbi Yose the Galilean says: [the infant] is a firstborn [with respect] to inheritance and for redemption from a priest, as it says: “Whatever opens the womb in Israel” (Exodus 13:2), meaning only if it opens the womb in Israel. If one had children already and married a woman who had never given birth previously Or if she converted when pregnant, or if she was freed when pregnant, and she gave birth; If she and a priestess gave birth, she and a Levite’s daughter, she and a woman who had already given birth; And similarly [if a woman] who did not wait three months after her husband's death, married and gave birth and it is not known if the infant was born in the ninth month since the death of the first [husband] or in the seventh month since she married the second, it is a firstborn for redemption from a priest but not a first-born [with respect] to inheritance. Which is a firstborn both [in respect] of inheritance and for redemption from a priest? If [a woman] miscarries a sac full of blood or full of water or full of pieces of flesh; or if [a woman] miscarries something with the shape of fish or locusts or reptiles, or creeping things, or if she discharges on the fortieth day [of conception], [the infant] which follows after [these discharges] is a firstborn both [in respect] of inheritance and for redemption from a priest.
Mishnah Chullin
The egg of a sheretz in which there has formed an embryo is clean. If it was pierced, however small the hole was, it is unclean. A mouse which is half flesh and half earth, if a man touched the flesh he becomes unclean, but if he touched the earth he remains clean. Rabbi Judah says: even if he touched the earth that is over against the flesh he becomes unclean.