The ovary is a female reproductive organ that plays a key role in fertility and the maintenance of endocrine homeostasis, which is of great importance to women’s health. It is characterized by a high heterogeneity, with different cellular subpopulations primarily containing oocytes, granulosa cells, stromal cells, endothelial cells, vascular smooth muscle cells, and diverse immune cell types. Each has unique and important functions. From the fetal period to old age, the ovary experiences continuous structural and functional changes, with the gene expression of each cell type undergoing dramatic changes. In addition, ovarian development strongly relies on the communication between germ and somatic cells. Compared to traditional bulk RNA sequencing techniques, the single-cell RNA sequencing (scRNA-seq) approach has substantial advantages in analyzing individual cells within an ever-changing and complicated tissue, classifying them into cell types, characterizing single cells, delineating the cellular developmental trajectory, and studying cell-to-cell interactions. In this review, we present single-cell transcriptome mapping of the ovary, summarize the characteristics of the important constituent cells of the ovary and the critical cellular developmental processes, and describe key signaling pathways for cell-to-cell communication in the ovary, as revealed by scRNA-seq. This review will undoubtedly improve our understanding of the characteristics of ovarian cells and development, thus enabling the identification of novel therapeutic targets for ovarian-related diseases.

Background: Gastric-type endocervical adenocarcinoma (GAS) is an aggressive, human papillomavirus-independent cervical adenocarcinoma, whereas lobular endocervical glandular hyperplasia (LEGH) is considered a potential precursor. Molecular and immune microenvironment differences between Peutz–Jeghers syndrome-associated LEGH (PJS-LEGH) and GAS (PJS-GAS) remain poorly characterized. This study aimed to characterize these differences through integrated transcriptomic analysis. Methods: Bulk RNA sequencing was performed on tissues from 7 PJS-LEGH and 8 PJS-GAS cases. Differential expression and functional enrichment analyses were integrated with weighted gene co-expression network analysis (WGCNA), molecular interaction network analysis, and machine learning. Immune-related transcriptional patterns were assessed using single-sample gene set enrichment analysis (ssGSEA) and xCell, with CD45/CD4 multiplex immunofluorescence for preliminary tissue-level assessment. Results: We identified 1794 differentially expressed genes, including 976 upregulated and 818 downregulated genes in PJS-GAS. Functional and network analyses highlighted differences involving ciliary biology, epithelial differentiation, chemokine signaling, and immune regulation. ssGSEA revealed higher scores for selected T-cell, dendritic-cell, monocyte, and myeloid-derived suppressor cell signatures in PJS-GAS. xCell provided complementary evidence of higher scores for selected immune-cell populations, together with activation- and inhibition-associated transcriptional signatures. Integrated analyses converged on PTPRC, encoding the pan-leukocyte marker CD45, as a prominent leukocyte-associated feature of PJS-GAS. Multiplex immunofluorescence showed higher CD45⁺ and CD4⁺ cell densities in the sampled PJS-GAS tissues. Conclusions: This study provides the first transcriptomic comparison of PJS-LEGH and PJS-GAS and identifies distinct molecular features and increased immune-cell-associated transcriptional signatures with coexisting activation- and inhibition-associated expression patterns in PJS-GAS.