OPINIONS: The Gemara explains that we see from the Mishnah that any part of
the animal that hardens as the animal matures, but could be eaten by being
boiled well, is considered meat (Basar) of the Korban Pesach and one can
fulfill his obligation to eat the Korban Pesach by being allocated those
parts.
The Beraisa states that soft sinews (Gidin) are also considered Basar. On
the other hand, we know that the sinews of the neck are not considered Basar
(Rav's statement, on 83b).
We see, then, that there are two different types of Gidin -- one type which
the Beraisa permits as Basar, and another type which is not considered
Basar.
The Gemara then brings an argument between Rebbi Yochanan and Reish Lakish
concerning sinews which are soft now but will become hard later ("Gidin
she'Sofan l'Hakshos"). To which sinews does this refer? If it is referring
to the sinews of the neck, everyone agrees that they are not Basar! If it is
referring to the soft sinews, everyone agrees that they *are* Basar, as the
Beraisa itself states; even if those soft sinews are going to become hard,
they are permitted since they can be cooked and softened. Where, then, does
the argument between Rebbi Yochanan and Reish Lakish apply?
(a) RASHI explains that the argument involves the sinews of the neck. Even
though Rav said that they are *not* considered Basar, Rebbi Yochanan
apparently argues with Rav and says that they are considered Basar. He
apparently holds that although they are hard, since they could be softened
through boiling they are considered Basar -- just like the ligaments
mentioned in our Mishnah. Why does Reish Lakish (and Rav) argue that they
are not considered meat, if they can be softened through cooking (as the
Gemara makes clear)? Apparently, they hold that cooking the sinews of the
neck will not soften them *sufficiently*, and thus they are not comparable
to the Gidin mentioned in the Beraisa which may be completely softened
through cooking.
(b) TOSFOS, citing the RI (DH Gidin and DH Ho'il), explains that Reish
Lakish and Rebbi Yochanan argue over a third type of Gidin, the Gidin of the
spinal column. He suggests that these Gidin -- although they can be softened
by being cooked -- are still not considered Basar according to Reish Lakish,
because they do not *taste* at all like meat. In this respect, they are not
similar to the cartilage mentioned in the Mishnah, which not only can be
softened by cooking after it hardens, but it also has the taste of meat.
Alternatively, Tosfos suggests that these Gidin become hard even while the
animal is *young*. Therefore, the fact that they could be cooked and made
soft cannot make them into "meat." The cartilage mentioned in the Mishnah,
on the other hand, only hardens after the animal gets older.
Both types of Gidin, according to both explanations, differ from the sinews
of the neck, which are hard from the start, Tosfos asserts, and are
therefore not considered to be meat according to anyone, even if they can be
softened by cooking.