Biology subjects

McKey, J.

Publications and source records attributed to McKey, J..

7 recordsLinked to original sources

bioRxiv2025

Rete Ovarii Epithelial Cells as an Unappreciated Cell of Origin for Pelvic and Ovarian High-Grade Serous Carcinoma

Over the past two decades, converging clinicopathologic, molecular, and evolutionary evidence has established that pelvic and ovarian high-grade serous carcinoma (HGSC) originates predominantly from tubal-type epithelia rather than the ovarian surface epithelium. Consequently, Fallopian tube secretory epithelial cells are widely recognized as the principal cell of origin for HGSC. However, the female reproductive tract contains additional tubular epithelial networks whose potential contributions to HGSC pathogenesis remain unexplored. Here, we identify the rete ovarii (RO), a complex network of intra- and extra-ovarian tubules located within the ovarian hilus and mesovarium, as an alternative candidate tissue of origin for HGSC. We demonstrate that genetic and genomic alterations in rete ovarii epithelial cells (ROECs) can drive their malignant transformation, giving rise to tumors that closely recapitulate the histologic and molecular characteristics of human HGSC. Spatially resolved single-cell transcriptomic analyses of tumors derived from Brca/Trp53/Pten-deficient ROECs (BTP-RO) reveal distinct invasive and immunosuppressive molecular programs. These findings establish ROECs as a previously unrecognized cell of origin for HGSC, expanding the landscape of potential precursor populations beyond the Fallopian tube. The RO-based HGSC model provides a powerful framework for developing origin-informed prevention strategies, early detection approaches, and targeted therapeutics.

cancer biology↗

bioRxiv2025

Ovarian development is driven by early spatiotemporal priming of the coelomic epithelium

Ovarian organogenesis relies on the coordinated specification of supporting and steroidogenic lineages from multipotent coelomic epithelium (CE) progenitors. However, it remains unclear how ovarian cellular diversity arises and whether CE progenitors are fate-biased before or after ingression into the gonad. We show that CE cells in fetal mouse and human ovaries are transcriptionally heterogeneous and spatially organized into subdomains already primed toward supporting or steroidogenic identities. CE priming is dynamic, influenced by proximity to the mesonephros, with a transient coexistence of both progenitor types before resolution toward a predominantly supporting-biased CE. In mice, delamination of primed CE cells seeds intragonadal niches that generate pre-granulosa and steroidogenic progenitors. We further demonstrate that fetal steroidogenic progenitors give rise to adult stromal and theca cells, and that granulosa cells have a dual origin from CE-derived and supporting-like cells. Together, these findings reveal a conserved, spatially encoded program of ovarian lineage specification.

developmental biology↗

bioRxiv2025

Single-cell-scale spatial transcriptome of the developing and adult mouse ovary

Mammalian ovary development is essential for female fertility, involving the complex spatial patterning of diverse cell types to establish the finite reserve of ovarian follicles. To uncover molecular mechanisms driving regionalization of the ovary while maintaining its native cellular architecture, we used Visium HD spatial transcriptomics. Our study captures all ovarian cell types at eight timepoints, generating a near single cell resolution library of spatial gene expression across development. Our analysis identified a previously uncharacterized "medullary core" domain that emerges by E16.5. Pre-granulosa cells (PGs) within this core express genes typically restricted to growing follicles in the postnatal ovary (Nr5a2, Slc18a2, Ephx2) suggesting core PGs are poised for activation while still in the fetal environment. This study provides a comprehensive architectural and molecular blueprint of the ovary, representing a fundamental resource for the investigation of regulatory mechanisms driving spatial patterning of the ovary and opens new avenues to explore the spatial determinants of female fertility and reproductive longevity. TeaserVisium HD provides a comprehensive blueprint of the mouse ovary, revealing a medullary core of activation-poised pregranulosa cells.

developmental biology↗

bioRxiv2024

OoCount: A machine-learning based approach to mouse ovarian follicle counting and classification

The number and distribution of ovarian follicles in each growth stage provides a reliable readout of ovarian health and function. Leveraging techniques for three-dimensional (3D) imaging of ovaries in toto has the potential to uncover total, accurate ovarian follicle counts. However, because of the size and holistic nature of these images, counting oocytes is time consuming and difficult. The advent of deep-learning algorithms has allowed for the rapid development of ultra-fast, automated methods to analyze microscopy images. In recent years, these pipelines have become more user-friendly and accessible to non-specialists. We used these tools to create OoCount, a high-throughput, open-source method for automatic oocyte segmentation and classification from fluorescent 3D microscopy images of whole mouse ovaries using a deep-learning convolutional neural network (CNN) based approach. We developed a fast tissue-clearing and spinning disk confocal-based imaging protocol to obtain 3D images of whole mount perinatal and adult mouse ovaries. Fluorescently labeled oocytes from 3D images of ovaries were manually annotated in Napari to develop a machine learning training dataset. This dataset was used to retrain StarDist using a CNN within DL4MicEverywhere to automatically label all oocytes in the ovary. In a second phase, we utilize Accelerated Pixel and Object Classification, a Napari plugin, to classify labeled oocytes and sort them into growth stages. Here, we provide an end-to-end protocol for producing high-quality 3D images of the perinatal and adult mouse ovary, obtaining follicle counts and staging. We also demonstrate how to customize OoCount to fit images produced in any lab. Using OoCount, we can obtain accurate counts of oocytes in each growth stage in the perinatal and adult ovary, improving our ability to study ovarian function and fertility. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/593993v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@8d7257org.highwire.dtl.DTLVardef@4dbe73org.highwire.dtl.DTLVardef@1283aaorg.highwire.dtl.DTLVardef@1822baf_HPS_FORMAT_FIGEXP M_FIG C_FIG Summary sentenceThis protocol introduces OoCount, a high-throughput, open-source method for automatic oocyte segmentation and classification from fluorescent 3D microscopy images of whole mouse ovaries using a machine learning-based approach.

developmental biology↗

bioRxiv2023

Rediscovering the Rete Ovarii: a secreting auxiliary structure to the ovary

The rete ovarii (RO) is an appendage of the ovary that has been given little attention. Although the RO appears in drawings of the ovary in early versions of Grays Anatomy, it disappeared from recent textbooks, and is often dismissed as a functionless vestige in the adult ovary. Using PAX8 immunostaining and confocal microscopy, we characterized the fetal development of the RO in the context of the ovary. The RO consists of three distinct regions that persist in adult life, the intraovarian rete (IOR), the extraovarian rete (EOR), and the connecting rete (CR). While the cells of the IOR appear to form solid cords within the ovary, the EOR rapidly develops into a convoluted tubular epithelium ending in a distal dilated tip. Cells of the EOR are ciliated and exhibit cellular trafficking capabilities. The CR, connecting the EOR to the IOR, gradually acquires tubular epithelial characteristics by birth. Using microinjections into the distal dilated tip of the EOR, we found that luminal contents flow towards the ovary. Mass spectrometry revealed that the EOR lumen contains secreted proteins potentially important for ovarian function. We show that the cells of the EOR are closely associated with vasculature and macrophages, and are contacted by neuronal projections, consistent with a role as a sensory appendage of the ovary. The direct proximity of the RO to the ovary and its integration with the extraovarian landscape suggest that it plays an important role in ovary development and homeostasis.

developmental biology↗

bioRxiv2023

Transcriptome analysis of the mouse fetal and adult rete ovarii and surrounding tissues

The rete ovarii (RO) is an epithelial structure that arises during fetal development in close proximity to the ovary and persists throughout adulthood in mice. However, the functional significance of the RO remains elusive, and it has been absent from recent discussions of female reproductive anatomy. The RO comprises three distinct regions: the intraovarian rete (IOR) within the ovary, the extraovarian rete (EOR) in the periovarian tissue, and the connecting rete (CR) linking the EOR and IOR. We hypothesize that the RO plays a pivotal role in maintaining ovarian homeostasis and responding to physiological changes. To uncover the nature and function of RO cells, we conducted transcriptome analysis, encompassing bulk, single-cell, and nucleus-level sequencing of both fetal and adult RO tissues using the Pax8-rtTA; Tre- H2B-GFP mouse line, where all RO regions express nuclear GFP. This study presents three datasets, which highlight RO-specific gene expression signatures and reveal differences in gene expression across the three RO regions during development and in adulthood. The integration and rigorous validation of these datasets will advance our understanding of the ROs roles in ovarian development, female maturation, and adult female fertility. Short narrativeThis study employs comprehensive bulk, single cell and single nucleus transcriptome analysis to uncover gene expression signatures of the fetal and adult rete ovarii (RO).

developmental biology↗

bioRxiv2021

Integration of mouse ovary morphogenesis with developmental dynamics of the oviduct, ovarian ligaments, and rete ovarii.

Morphogenetic events during development of the fetal ovary are crucial to the establishment of female fertility. However, the effects of structural rearrangements of the ovary and surrounding reproductive tissues on ovary morphogenesis remain largely uncharacterized. Using tissue clearing and lightsheet microscopy, we found that ovary folding correlated with regionalization into cortex and medulla. Relocation of the oviduct to the ventral aspect of the ovary led to ovary encapsulation, and mutual attachment of the ovary and oviduct to the cranial suspensory ligament likely triggered ovary folding. Development of the rete ovarii correlated with events of ovary morphogenesis. Using genetic mouse models in which the oviduct and rete ovarii are perturbed, we found the oviduct is required for ovary encapsulation. This study reveals novel relationships among the ovary and surrounding tissues and paves the way for functional investigation of the relationship between architecture and differentiation of the mammalian ovary.

developmental biology↗