We move on to Mishnah 5 in Chapter 6 of Tractate Bechoros, which deals with blemishes in the reproductive organs and the tail.
Blemishes in the Reproductive Organs:
A male ox or sheep has a reproductive organ like all animals, but it is somewhat of an internal organ: even though it extends outward, it is usually contained within a protective pouch called the orlah - skin that surrounds and protects the organ. Therefore, if the organ itself is damaged, it is not a blemish, because it is internal. However, "nifgam hazovan" - if the orlah, the skin that protects the pouch from the outside, is impaired and is missing a piece, it does not heal, and it is a permanent blemish.
"O ervah shebanekevos bamukdashin" - this refers to female consecrated animals, and it is understood that this is not in a bechor but in other types of offerings, such as shelamim (peace offerings). 'Ervah' means the reproductive organs. If a piece of flesh is missing from the external reproductive organs, which are somewhat visible from the outside, she too is blemished and may be slaughtered.
Blemishes in the Tail:
The tail is composed of about twenty bones connected to each other and surrounded by muscle and skin, while at its tip there is only flesh without bone. Based on this, the Mishnah lists several blemishes:
"Nifgam hazanav min ha'etzem" - a piece is missing from the tail, and the impairment reaches the bone, such that a part of one of the tail vertebrae is missing: this is a permanent blemish.
"Aval lo min haperek" - if the missing part is from the joint between the bones, between the links of the chain of about twenty tailbones, this is not a permanent blemish, because it heals.
"O shel rosh hazanav mafzil etzem" - if the tip of the tail is torn or peeled so that the bone is exposed at its end, it is blemished.
"O sheyesh basar bein chulya lechulya melo etzba" - if a gap of flesh the width of a finger, like the width of a thumb, is created between the vertebrae of the tail, this is a defect visible from the outside, and the bechor becomes permanently blemished, does not heal, and may be slaughtered.
In summary: In this Mishnah we learned about the blemishes in the reproductive organs - an impairment of the zovan in a male and an impairment of the ervah in consecrated females - and the blemishes in the tail: an impairment that reaches the bone, a tail tip where the bone is exposed, and a gap of flesh the width of a finger between one vertebra and another. In contrast, an impairment in the joint between the bones is not a permanent blemish, because it heals.