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Thanks for the. Mammaries. Breasts, udders, teats, nipples, etc. etc. etc.
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Thanks for the . . . . . Mammaries Breasts, udders, teats, nipples, etc. etc. etc.
During the fifth week of human development, the embryo develops a milk line that extends from the armpit to the groin. This usually disappears, forming the breast tissue. In 2-6% of women however this band persists and accessory breast tissue can occur anywhere along this line. This accessory tissue may be in the form of accessory nipples to fully developed and functioning breast tissue.
Lactation: providing mammal offspring with preventive health, curative medicine, and oh yes, food, too • . . . . We might expect that litter-bearing species (that have multiple offspring) would have glands all along the ventral surface (along the milk line), while species bearing only singles or twins would have glands located in only one area of the underside. This is generally the case. Below are several examples of species that reflect the range of anatomical location and number of glands.
Naked Mole Rats A breeding female from a Cornell laboratory colony of naked mole-rats offers proof that biologists' "one-half rule" for mammary glands does not apply to all mammals. Unlike humans and most other mammals, nursing naked mole-rats often have many more pups than mammary glands. (12 mammae and 28 pups at a time; they take turns; they share)
“Glands” vs. “teats” or “nipples” • A cow has 4 teats and 4 glands • A sow may have 12 teats and 24 glands • A mare has 2 teats and 4 glands • A feline queen has eight nipples and 32 glands • A woman has 2 nipples and 30 glands
Definitions • Perhaps some definitions will help. With the exception of monotremes that do not have nipples, mammals with teats or nipples may have one or more openings per teat. The milk collecting system, including the alveoli and ducts, is interconnected and continuous through to the opening in the nipple. A simple mammary gland includes those alveoli and ducts that empty via one teat opening. Many mammals have multiple simple glands that lead to separate openings in the nipple and empty independently.
The “milk line” – two parallel lines running from armpits to groin. Evenly spaced pairs of mammary glands. Some animals have many, some have two, some have four; some, such as the elephant, have only the first pair (in armpits); humans have only the second pair, on our chests; some animals have only the last pair (or pairs) coalesced into an udder.
First signs of breast development in a pre-adolescent/adolescent girl “Breast buds”
Normal but not common variations: Hairs at circum-areolar margins
Normal but not common variations: Inverted nipples (usually come out on their own in response to baby’s suckling).
Normal breast: Nursing mother Note development of improved blood supply to the breast.
Normal breast Indistinct edge of areola.
Same woman, post-partum, perfectly adequate for breastfeeding
Normal breast Large pale areolas.
Normal variation Downward facing areolas/nipples in large-breasted woman.
Normal breast Variation in nipple form
Normal breasts Protruding nipples
Asymmetrical Breasts • Overall size • Overall shape • Areolas • Nipples
“Virginal” hypertrophy Overgrowth (hypertrophy) of one breast during puberty.
Most women have asymmetrical breasts; which one is bigger/smaller may change over the course of your lifetime.
Tubular Breasts: Insufficient Glandular Tissue Also, in this woman, little differentiation between breast, areola, and nipple. Flat nipples.
Tubular breasts Nipple and areola formation normal, but little/no glandular tissue. Very unlikely to be successful at breastfeeding.
