Biologists link sexual selection and placenta formation

Sexual selection refers to species' selection for traits that are attractive to the opposite sex. This special type of natural selection enhances opportunities to mate, the tail of male peacocks being an iconic example.

Scientists watch evolution in action

(PhysOrg.com) -- The yellow-bellied three-toed skink (Saiphos equalis) is one of only three reptiles known to have different methods of reproduction in different places. In the coastal areas of New South Wales (NSW), near ...

Nanoparticles may cause DNA damage across a cellular barrier

(PhysOrg.com) -- Scientists have shown in the laboratory that metal nanoparticles damaged the DNA in cells on the other side of a cellular barrier. The research, by the University of Bristol, is published online this week ...

Cause of oversized placentas in cloning found after two decades

One reason a technique for cloning animals often results in oversized placentas, and hence failed births, has been uncovered in mice by an all-RIKEN team. This finding will help improve the success rate of the cloning method ...

Study shows placenta truly is a bacteria-free zone

A team of researchers at the University of Cambridge has found evidence indicating that the human placenta is a sterile environment. In their paper published in the journal Nature, the group describes their study of the placental ...

Marsupial moms express placental genes in milk

Modern mothers, whether they be human or mouse, might be forgiven for envying marsupial mamas. Rather than enduring a long pregnancy and the birth of a relatively well-developed—and comparatively large—baby, kangaroos, ...

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Placenta

The placenta is an organ unique to mammals that connects the developing fetus to the uterine wall. The placenta supplies the fetus with oxygen and food, and allows fetal waste to be disposed of via the maternal kidneys. The word placenta comes from the Latin for cake, from Greek plakóenta/plakoúnta, accusative of plakóeis/plakoús - πλακόεις, πλακούς, "flat, slab-like", referring to its round, flat appearance in humans. Protherial (egg-laying) and metatherial (marsupial) mammals produce a choriovitelline placenta that, while connected to the uterine wall, provides nutrients mainly derived from the egg sac. The placenta develops from the same sperm and egg cells that form the fetus, and functions as a fetomaternal organ with two components, the fetal part (Chorion frondosum), and the maternal part (Decidua basalis).

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