Related Experiment Video
Updated: Jun 24, 2026

Isolation of Primary Human Decidual Cells from the Fetal Membranes of Term Placentae
Published on: April 30, 2018
The cytoplasmic 60 kDa progesterone receptor isoform predominates in the human amniochorion and placenta at term
Anthony H Taylor1, Penny C McParland, David J Taylor
1Preterm Birth Research Group, Reproductive Sciences, Department of Cancer Studies and Molecular Medicine, University of Leicester, Leicester, Leicestershire, LE2 7LX, UK. aht3@le.ac.uk
Background:
The mechanism that initiates human parturition has been proposed to be 'functional progesterone withdrawal' whereby the 116 kDa B-isoform of the progesterone receptor (PR-B) switches in favour of the 94 kDa A-isoform (PR-A) in reproductive tissues. Recently, other PR isoforms, PR-S, PR-C and PR-M generated from the same gene have been identified and partially characterised.
Methods And Results:
Using immunohistochemical, western blotting and RT-PCR techniques, evidence is provided that indicates the major PR isoform present in human term fetal membranes (amnion and chorion) and syncytiotrophoblast of the placenta is neither of the classical nuclear PR-B or PR-A isoforms but is the N-terminally truncated 60 kDa PR-C isoform. Evidence is also provided that this 60 kDa isoform resides in the cytoplasm of the expressing cell types. Data are also presented to show that PR-B, PR-A and PR-S isoforms are essentially absent from the amnion and chorion, whereas PR isoforms A, B, C and S are all present in the decidua, with PR-A being the major isoform. The syncytiotrophoblast of the placenta contains the cytoplasmic 60 kDa isoform, but not isoforms PR-A, PR-B or PR-S.
Conclusion:
The major PR isoform in the amnion, chorion and placenta is a 60 kDa protein that could be PR-C, suggesting that the cytoplasmic isoform has a specific role in extra-embryonic tissues and may be involved in the regulation of human parturition.
Related Concept Videos
Gonadal and Placental Hormones
In males, testosterone is the primary gonadal androgen. It plays a central role in the maturation of male reproductive organs — the penis and testes. Additionally, testosterone is instrumental in the development of secondary sexual characteristics — a deep voice as well as facial and pubic hair growth — and...
Transcytosis of IgG
IgG molecules from a mother undergo transcytosis starting around 13 weeks of gestation. The amount of IgG transferred and entering the fetal blood circulation increases with...
Ovarian Cycle
Intracellular Hormone Receptors
Types of Receptors: Internal Receptors
Similar to membrane-bound receptors, the binding of a ligand to the intracellular receptor of causes a conformational change in the...
Internal Receptors
