Crick evolutionary biologist Margarida Cardoso Moreira is working with conservation charity ZSL to investigate an enduring mystery: how the placenta has evolved with incredible variation across species.
Margarida with Timba, part of the herd of reticulated giraffes at Whipsnade Zoo, contributing to her research on how organs and cell types emerge during evolution.
Shortly after Leoni, a reticulated giraffe, was born at Whipsnade Zoo, keepers recovered the placenta that had sustained her for 15 months in the womb, allowing it to be studied at the Crick.
“I’m following in the footsteps of the naturalists of the 18th and 19th centuries, who went into the wild to describe the diversity of life they saw,” says Margarida Cardoso Moreira. “But I’m returning to nature with the help of ZSL, bringing cutting‑edge tools to analyse the placenta at the molecular level.”
The placenta first evolved in mammals around 160 million years ago. “We know less than we should” about this vital collaboration between mother and embryo.
“The Zoo fills a huge gap for us”, explains Margarida. “We can study farm animals, and small laboratory animals, but they’ve been carefully bred over generations. By studying placentas recovered at the zoo, we can access a much broader range of natural diversity.”
The Whipsnade herd's newest arrival – four-and-a-half-week-old Leoni and her mother Luna. Credit: Fiona Hanson
A key question for Margarida is, why are placentas from different mammalian species made up of different types of cells? Other organs, such as the liver or heart, are made up of the same cell types across mammalian species. But the human placenta has fewer cell types than that of a mouse.
“The placenta is the site of cell-type innovation,” says Margarida, “which makes it uniquely well suited to understand how cell types evolve.”
“Placentas from different species are incredibly diverse,” says Margarida.
Across the surface of a 5kg giraffe placenta are numerous cotyledons which attach to the wall of the mother’s uterus. Each is rich in tiny blood vessels which absorb nutrients and oxygen from the mother’s blood and carry them to the fetus, and return waste.
“The giraffe placenta is a large membrane with more than a hundred attachments. In dogs and cats the placenta forms a band around the embryo and attaches continuously, while in humans it is disc-shaped with a single area of attachment.”
Leading the analysis of data from the project is postdoctoral research assistant Marcin Falis. “Comparing the molecular make-up of individual cells from placentas of different species allows us to reconstruct the history of how placentas have evolved and how different cell types originated,” he explains.
One area Margarida is particularly eager to understand is how certain placental cells infiltrate the mother’s uterus, coming in to direct contact with cells from her immune system. “It’s the only time when our immune system doesn’t kill non-self cells it encounters. Understanding how this happens could ultimately help us develop ways of helping the body accept, rather than reject, organ transplants.”
Along with the placenta sample from Leoni and Luna, and others from rhinos, elephants and other giraffes Margarida has already analysed, she hopes to add more from other species at Whipsnade and London Zoo.
“The zoo fills a huge gap for us”, says Margarida, “creating a rare opportunity to study life at its most extraordinary.”
As an evolutionary biologist, this collaboration offers a valuable opportunity to study the “endless forms most beautiful” that Charles Darwin saw in evolution.
“Partnering with ZSL opens doors to species we could never study otherwise – creating a rare opportunity to explore life at its most extraordinary,” says Margarida.
“These animals may hold the key to unlocking some of biology’s greatest mysteries, and through this partnership, we’re bringing those discoveries within reach.”
