The evolution of epitheliochorial placentation.
Abstract: Epitheliochorial placentation is a derived condition and has evolved separately in strepsirrhine primates and laurasiatherians (pangolins, whales, and hoofed mammals). Usually it is associated with a long gestation period, small litters, and precocial young. Oxygen transfer is facilitated by indenting of the uterine and trophoblast epithelia by maternal and fetal capillaries, respectively. Histotrophic nutrition is important, and adaptations include areolas and hemophagous regions. In pigs and horses, for example, iron is transported as uteroferrin secreted from the uterine glands and taken up by areolas. In the horse, invasive trophoblast cells form cups within the endometrium that are the source of equine chorionic gonadotropin. In ruminants, binucleate trophoblast cells fuse with uterine epithelial cells to form trinucleate cells or plaques that secrete pregnancy hormones. There is evidence of immunosuppression in connection with these more invasive types of trophoblasts. The epitheliochorial condition may be advantageous for long pregnancies in large animals.
Publication Date: 2013-01-03 PubMed ID: 25387027DOI: 10.1146/annurev-animal-031412-103653Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Review
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research article focuses on the evolutionary history and adaptive features of epitheliochorial placentation, a type of placentation observed in certain mammals like strepsirrhine primates, pangolins, whales, and hoofed mammals.
Understanding Epitheliochorial Placentation
- This form of placentation involves the interaction between the epithelial layer of the maternal uterus and the trophoblast cells (fetal cells) of the placenta, without any damage to the maternal tissue or cellular invasion.
- It’s generally associated with long gestation periods, small litters (number of offspring per pregnancy), and precocial young (offspring that are relatively mature and mobile from the moment of birth).
- It’s a distinct form of placentation that emerged separately in two different mammalian lineages: strepsirrhine primates (like lemurs and lorises) and laurasiatherians (which include mammals like pangolins, whales, and hoofed animals).
Oxygen Transfer and Histotrophic Nutrition
- In this type of placentation, oxygen transfer between the mother and fetus is facilitated by the indenting of the uterine and trophoblast epithelia by maternal and fetal capillaries, respectively.
- Epitheliochorial placentation is also characterized by histotrophic nutrition, where nutrients are derived from uterine secretions and maternal blood rather than directly through the placenta.
- Adaptations observed in this context include areolas (local thickenings in the placenta) and hemophagous regions (areas involved in the absorption of maternal blood).
Specific Features in Pigs and Horses
- In pigs and horses, iron transportation to the fetus is facilitated by a protein called uteroferrin, secreted from the uterine glands and absorbed by areolas.
- In horses, invasive trophoblast cells form structures called ‘cups’ within the endometrium (lining of the uterus), which secrete the hormone equine chorionic gonadotropin.
Features in Ruminants
- In ruminants like cows, sheep, and deer, another unusual feature is observed where binucleate trophoblast cells (containing two nuclei) fuse with uterine epithelial cells to form trinucleate cells or plaques. These structures can secrete pregnancy hormones.
- Studies indicate immunosuppressive activity in the context of these more invasive types of trophoblasts, likely aiding in preventing maternal immune rejection of the fetus.
Advantages of Epitheliochorial Placentation
- The study concludes by suggesting that the epitheliochorial form of placentation may confer certain advantages for species with long pregnancies, particularly large animals. The precise nature of these benefits, however, requires further research.
Cite This Article
APA
Carter AM, Enders AC.
(2013).
The evolution of epitheliochorial placentation.
Annu Rev Anim Biosci, 1, 443-467.
https://doi.org/10.1146/annurev-animal-031412-103653 Publication
Researcher Affiliations
- Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense DK-5000, Denmark; email: acarter@health.sdu.dk.
MeSH Terms
- Animals
- Biological Evolution
- Female
- Mammals / genetics
- Mammals / physiology
- Placenta / physiology
- Pregnancy
Citations
This article has been cited 23 times.- Sawyer S, Stas MR, Lagumdzic E, Stadler M, Kreutzmann H, Knecht C, Dolezal M, Saalmüller A, Rümenapf T, Mair KH, Buzanich-Ladinig A. Investigating the functional capacity of porcine uterine natural killer cells during a porcine reproductive and respiratory syndrome virus infection of pregnant gilts. Vet Res 2025 Oct 7;56(1):189.
- Kandil B, Turgut AO, Koca D, Isbilir F, Atli MZ, Guzel BC. Comprehensive Evaluation of Changes in Placentomes in the Second and Third Trimesters of Pregnancy in Cross-Bred Hamdani Sheep. Vet Med Sci 2025 Jan;11(1):e70208.
- Satué K, Fazio E, La Fauci D, Medica P. Hematological indexes and iron status in pregnant mares. Arch Anim Breed 2023;66(3):197-205.
- Navarrete Zamora MB, da Silva TS, da Silva MD, Almeida GHDR, da Silva-Júnior LN, Horvath-Pereira BO, Baracho Hill AT, Acuña F, Carreira ACO, Barreto RDSN, Sato AS, Miglino MA. Term alpaca placenta glycosylation profile and its correlation with pregnancy maintenance and fetal survival. Front Cell Dev Biol 2023;11:1193468.
- Orellana-Guerrero D, Uribe-Salazar JM, El-Sheikh Ali H, Scoggin KE, Ball B, Daels P, Finno CJ, Dini P. Dynamics of the Equine Placental DNA Methylome and Transcriptome from Mid- to Late Gestation. Int J Mol Sci 2023 Apr 11;24(8).
- Rebollada-Merino A, García-Seco T, Pérez-Sancho M, Domínguez L, Rodríguez-Bertos A. Histopathologic and immunohistochemical findings in the placentas and fetuses of domestic swine naturally infected with Brucella suis biovar 2. J Vet Diagn Invest 2023 May;35(3):258-265.
- Siriwardena D, Boroviak TE. Evolutionary divergence of embryo implantation in primates. Philos Trans R Soc Lond B Biol Sci 2022 Dec 5;377(1865):20210256.
- Tan C, Huang Z, Xiong W, Ye H, Deng J, Yin Y. A review of the amino acid metabolism in placental function response to fetal loss and low birth weight in pigs. J Anim Sci Biotechnol 2022 Mar 2;13(1):28.
- Carlson J, Kammerer R, Teifke JP, Sehl-Ewert J, Pfarrer C, Meyers G. A double deletion prevents replication of the pestivirus bovine viral diarrhea virus in the placenta of pregnant heifers. PLoS Pathog 2021 Dec;17(12):e1010107.
- Green JA, Geisert RD, Johnson GA, Spencer TE. Implantation and Placentation in Ruminants. Adv Anat Embryol Cell Biol 2021;234:129-154.
- Antczak DF, Allen WRT. Placentation in Equids. Adv Anat Embryol Cell Biol 2021;234:91-128.
- D' Fonseca NMM, Gibson CME, van Doorn DA, Roelfsema E, de Ruijter-Villani M, Stout TAE. Effect of Overfeeding Shetland Pony Mares on Embryonic Glucose and Lipid Accumulation, and Expression of Imprinted Genes. Animals (Basel) 2021 Aug 26;11(9).
- Brown JA, Niland ES, Pierce NL, Taylor JB. Validation of fetal microchimerism after pregnancy in the ovine using qPCR. Transl Anim Sci 2021 Apr;5(2):txab100.
- Carter AM. Unique Aspects of Human Placentation. Int J Mol Sci 2021 Jul 28;22(15).
- Stefanetti V, Pascucci L, Wilsher S, Cappelli K, Capomaccio S, Reale L, Passamonti F, Coletti M, Crociati M, Monaci M, Marenzoni ML. Differential Expression Pattern of Retroviral Envelope Gene in the Equine Placenta. Front Vet Sci 2021;8:693416.
- Alberio R, Kobayashi T, Surani MA. Conserved features of non-primate bilaminar disc embryos and the germline. Stem Cell Reports 2021 May 11;16(5):1078-1092.
- Carter AM. Evolution of placentation in cattle and antelopes. Anim Reprod 2020 May 22;16(1):3-17.
- Weström B, Arévalo Sureda E, Pierzynowska K, Pierzynowski SG, Pérez-Cano FJ. The Immature Gut Barrier and Its Importance in Establishing Immunity in Newborn Mammals. Front Immunol 2020;11:1153.
- Laird MK, Hansen VL, McAllan BM, Murphy CR, Thompson MB. Uterine epithelial remodelling during pregnancy in the marsupial Monodelphis domestica (Didelphidae): Implications for mammalian placental evolution. J Anat 2020 Jun;236(6):1126-1136.
- Lindeberg H, Burchmore RJ, Kennedy MW. Pulse of inflammatory proteins in the pregnant uterus of European polecats (Mustela putorius) leading to the time of implantation. R Soc Open Sci 2017 Mar;4(3):161085.
- Hansen VL, Schilkey FD, Miller RD. Transcriptomic Changes Associated with Pregnancy in a Marsupial, the Gray Short-Tailed Opossum Monodelphis domestica. PLoS One 2016;11(9):e0161608.
- Carter AM, Enders AC, Pijnenborg R. The role of invasive trophoblast in implantation and placentation of primates. Philos Trans R Soc Lond B Biol Sci 2015 Mar 5;370(1663):20140070.
- Garrels W, Holler S, Taylor U, Herrmann D, Niemann H, Ivics Z, Kues WA. Assessment of fetal cell chimerism in transgenic pig lines generated by Sleeping beauty transposition. PLoS One 2014;9(5):e96673.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
