# Peg cell
A **peg cell** is a non-ciliated [secretory cell](https://www.edgepedia.org/secretory-cell) of the oviduct (fallopian tube) epithelium, wedged between the more numerous ciliated cells. The name traces to the German *Stiftchenzellen*, a rare third cell type identified over a century ago that appeared like slender pegs driven between the other cells; it has also been called an intercalary cell because the small cells were often found intercalated between adjacent ciliated and secretory cells.[1](https://pmc.ncbi.nlm.nih.gov/articles/PMC4442093/)
| Key fact | Detail |
|---|---|
| Definition | Non-ciliated secretory cell of the oviduct epithelium, wedged between ciliated cells[2](https://sites.tufts.edu/histologyimages/female-reproductive-system/670/epithelium-of-ovdicut-mucosa/) |
| Function | Secretes nutrient material for the ovum; secretion lubricates the tube and provides nourishment and protection to the traveling ovum[3](https://histology.leeds.ac.uk/home/female/oviduct/) • [4](https://www.medcell.org/histology/female_reproductive_system_lab/oviduct_epithelium.php) |
| Secretion | Nonciliated cells that secrete a glycoprotein film covering the epithelium[5](https://www.uomus.edu.iq/img/lectures21/MUCLecture_2025_51935988.pdf) |
| Timing | Particularly prominent at day 14 of the menstrual cycle, around the time of ovulation[3](https://histology.leeds.ac.uk/home/female/oviduct/) |
| Markers | Marked with EPCAM, CD44, and ITGA6; peg cell markers include LGR5, NOTCH2, COL1A2, and SERINC5[1](https://pmc.ncbi.nlm.nih.gov/articles/PMC4442093/) • [6](https://pmc.ncbi.nlm.nih.gov/articles/PMC11954873/) |
| Regenerative role | Peg cells can expand and form organoids containing both ciliated and secretory cells, indicating potential stem cell or progenitor properties[7](https://www.mdpi.com/2073-4409/15/3/269) |
## Structure and identification
The oviduct is lined by a simple columnar epithelium containing ciliated cells and non-ciliated secretory cells, with peg cells wedged between the ciliated cells.[2](https://sites.tufts.edu/histologyimages/female-reproductive-system/670/epithelium-of-ovdicut-mucosa/) Histologically, peg cells have darker nuclei that lie closer to the lumen than those of the ciliated cells.[2](https://sites.tufts.edu/histologyimages/female-reproductive-system/670/epithelium-of-ovdicut-mucosa/) They have an extensive [Golgi apparatus](https://www.edgepedia.org/golgi-apparatus) above the nucleus, toward the apical surface, consistent with their secretory function.[3](https://histology.leeds.ac.uk/home/female/oviduct/)
Some authorities classify the peg cell as a third epithelial cell type alongside ciliated and secretory cells, describing it as either an undifferentiated state or an altered, functionally depleted form of ciliated or secretory cells.[8](https://www.sciencedirect.com/topics/medicine-and-dentistry/oviduct) In the rat, an electron microscopic analysis reported that peg cells appear to be the morphological image of necrobiotic cells, either ciliated or secretory.[9](https://pubmed.ncbi.nlm.nih.gov/6114052/) Other work characterizes peg cells as a distinct cell type: in human fallopian tube, a basally located population marked with [EPCAM](https://www.edgepedia.org/epcam), CD44, and ITGA6 lacks both the ciliated marker TUBB4 and the secretory marker PAX8, and this cell was identified as the peg cell.[1](https://pmc.ncbi.nlm.nih.gov/articles/PMC4442093/)
## Function
Peg cells secrete fluid that provides nutrients for the ovum or fertilized zygote, and their secretion lubricates the tube and provides nourishment and protection to the traveling ovum.[4](https://www.medcell.org/histology/female_reproductive_system_lab/oviduct_epithelium.php) • [10](https://www.histologyguide.org/slideview/MHS-220-oviduct/18-slide-1.html) Together with ciliated cells, which move the ovum toward the uterus, they make the microenvironment of the oviduct suitable for gamete transport, fertilization, and zygote transport.[2](https://sites.tufts.edu/histologyimages/female-reproductive-system/670/epithelium-of-ovdicut-mucosa/) Their secretion has also been described as a glycoprotein film covering the epithelium.[5](https://www.uomus.edu.iq/img/lectures21/MUCLecture_2025_51935988.pdf)
The cells vary with the reproductive cycle. They are particularly prominent at day 14 of the menstrual cycle, around the time of ovulation.[3](https://histology.leeds.ac.uk/home/female/oviduct/) In a study of human oviducts, mature ciliated and secretory cells were observed only at mid-cycle, while atrophy, deciliation, and loss of secretory activity coincided with elevated serum progesterone.[11](https://onlinelibrary.wiley.com/doi/abs/10.1002/aja.1001560405)
## Stem-like properties and disease relevance
When separated from other tissue using a characteristic set of surface antigens, peg cells act as the fallopian tube's regenerative cells in vitro; such stem-like cells cluster at the tube's fimbriated far end and occur in greater numbers in tubal samples taken from patients with serous carcinoma.[1](https://pmc.ncbi.nlm.nih.gov/articles/PMC4442093/) [In vitro](https://www.edgepedia.org/in-vitro) studies have shown that peg cells can expand and form organoids containing both ciliated and secretory cells, indicating potential stem cell or progenitor properties.[7](https://www.mdpi.com/2073-4409/15/3/269)
Regional variation has been reported at the transcript level: markers of OVGP1-producing secretory cells identified as peg cells, including [LGR5](https://www.edgepedia.org/lgr5), NOTCH2, COL1A2, and SERINC5, were enriched approaching the ampulla, with highest expression in the ampulla and infundibulum and lower expression in the fimbria (fringed, finger-like open end of the fallopian tube) and isthmus in one dataset, though these trends were not replicated in a validation dataset.[6](https://pmc.ncbi.nlm.nih.gov/articles/PMC11954873/)
## References
1. [Paik et al. (2012). Stem-like epithelial cells are concentrated in the distal end of the fallopian tube: a site for injury and serous cancer initiation. STEM CELLS / PMC.](https://pmc.ncbi.nlm.nih.gov/articles/PMC4442093/)
2. [Epithelium of oviduct mucosa, Collection of Histology Images, Tufts University](https://sites.tufts.edu/histologyimages/female-reproductive-system/670/epithelium-of-ovdicut-mucosa/)
3. [Oviduct, The Histology Guide, University of Leeds](https://histology.leeds.ac.uk/home/female/oviduct/)
4. [Oviduct Epithelium, MedCell Histology](https://www.medcell.org/histology/female_reproductive_system_lab/oviduct_epithelium.php)
5. [Oviduct microscopic structure lecture, University of Al-Muthanna](https://www.uomus.edu.iq/img/lectures21/MUCLecture_2025_51935988.pdf)
6. [Spatial transcriptomic profiling of the human fallopian tube epithelium reveals region-specific gene expression patterns, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC11954873/)
7. [Functional Changes in the Fallopian Tube: Environmental Factors, Lifestyle, Pathological Conditions and Pharmacological Agents, Cells (MDPI)](https://www.mdpi.com/2073-4409/15/3/269)
8. [Oviduct, an overview, ScienceDirect Topics](https://www.sciencedirect.com/topics/medicine-and-dentistry/oviduct)
9. [Ultrastructure of the oviductal mucosa of the rat. III. Basal and peg cells. Int J Fertil 1980, PubMed](https://pubmed.ncbi.nlm.nih.gov/6114052/)
10. [Oviduct, Histology Guide slide MHS 220](https://www.histologyguide.org/slideview/MHS-220-oviduct/18-slide-1.html)
11. [Verhage 1979, Cyclic changes in ciliation, secretion and cell height of the oviductal epithelium in women, American Journal of Anatomy](https://onlinelibrary.wiley.com/doi/abs/10.1002/aja.1001560405)
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