Anatomic characteristics of epididymis based on histology, proteomic, and 3D reconstruction

Abstract

Background The epididymis is a popular research topic in urology and reproduction. Objectives To explore and identify the anatomical characteristics of the epididymis based on histology, proteomics, and 3D reconstruction of epididymal tubules. Materials and methods A 3D reconstruction of epididymal tubules was generated based on 7‐μm‐thick transverse serial sections of an epididymis. The proteins in the subcompartments of the epididymis were obtained and analyzed by non‐labeled sequential window acquisition of all theoretical fragment ion spectra mass spectrometry (SWATH MS). Protein function, signaling pathways, protein expression, and the histology in different subcompartments were analyzed. Results The caput (Cap), corpus (Cor), and cauda (Cau) of the epididymis were divided into 6, 10, and 4 subcompartments, respectively, and the subcompartment between the Cap and Cor is mixed together. A total of 3411 proteins were identified, and 854 proteins were accurately quantified after screening. When the subcompartment Cap 5 transitioned to Cap 6 and Cap 6 to Cap 7, 87 and 52 proteins were upregulated and 14 and 7 proteins were downregulated, respectively. The Cor 9 transition to Cau 1 was marked by 230 proteins that were downregulated, while 74 proteins were upregulated. At the junction of the cauda and the vas deferens, 57 proteins were downregulated, and 410 proteins were upregulated. Cap 6 histology was consistent with that of Cor 1. Discussion and conclusion The epididymis contains distinct connective tissue septa that can be identified under a surgical tabletop microscope, enabling it to be divided into 20 subcompartments.

The significance of single-cell transcriptome analysis in epididymis research

“…The corpus of the epididymis plays a pivotal role in immune functions. The comprehension of the epididymis evolved from its initial morphological and structural characterization to encompass diverse functional aspects across different regions ( Martin et al, 1902 ; Sullivan et al, 2019 ; James et al, 2020 ; Zhao et al, 2020 ). Notably, unique gene expression patterns were identified in the caput, corpus, and cauda regions through techniques such as microarray or single-cell RNA sequencing analysis.…”

“…Anatomical analysis of the human epididymis based on histology, proteomics data and 3D reconstruction had led to a subdivision of the caput, corpus and cauda into four six and ten regions respectively ( Zhao et al, 2020 ). This research revealed significant variations in protein composition within different luminal regions of the epididymis ( Dacheux et al, 2006 ).…”

Functional genomics of the human epididymis: Further characterization of efferent ducts and model systems by single‐cell RNA sequencing analysis

“…Over the past few years, we have made a concerted effort to study the human epididymis using functional genomics protocols in concert with primary cell [10][11][12][13][14][15] and organoid 16 models to investigate the biology of the human organ and its response to androgens. There are multiple challenges in researching the human epididymis: first, the paucity of human tissue samples; second, the apparent lack of complete septa dividing the functional regions of the human epididymis making characterization of each region somewhat problematic (septa have been observed, [17][18][19] though their biological properties are not fully characterized); third, the dramatic diversity in structure among different individuals. Extensive morphological and anatomical studies on the human organ have provided a valuable encyclopedia of the human epididymis (reviewed in 19,20 ), however, in real-time it is often difficult to correlate this information with fresh tissue samples when histology is not possible.…”