Anat Rec (Hoboken). 2016 Dec 16. doi: 10.1002/ar.23531. [Epub ahead of print]

Expression of epithelial and mesenchymal differentiation markers in the early human gonadal development.

Martinovic V¹, Vukusic Pusic T², Restovic I³, Bocina I⁴, Filipovic N^5,6, Saraga-Babic M⁶, Vukojevic K^6,7.

Abstract

Expressions of cytokeratin 8 (CK8), vimentin, nestin and alpha-smooth-muscle-actin (alpha-SMA) were analyzed in the developing gonads of 12, 5-9 week old (W) human conceptuses by immunohistochemistry and immunofluorescence. During the investigated period, the number of CK8 positive cells increased from 56% to 92% in the gonadal surface epithelium, from 50% to 60% in the stroma, and from 23% to 42% in the medulla. In the early fetal period, the cell expression of CK8 increased in all gonadal parts, whereas primordial germ cells (PGC) remained negative. The expression of vimentin increased in the gonad stroma from 73% to 88%, and in the surface epithelium from 18% to 97% until 9^th W. The medulla had the highest expression of vimentin in the 7^th -8^th W (93%). Vimentin and CK8 co-localized in the somatic cells, while some PGCs showed vimentin expression only. Initially, nestin was positive in the gonad surface epithelium (8%) and stroma (52%), however during further development it decreased to 1% and 33% respectively. In the early fetal period, the nestin positive cells decreased from 44% to 31% in the gonad medulla. Alpha-SMA was positive only in the blood vessels and mesonephros. The described pattern of expression of intermediate filaments (IF) in developing human gonads suggests their role in the control of PGC apoptosis, early differentiation of gonad stromal cells and cell migration. Both epithelial and mesenchymal origins of follicular cells and possible epithelial-to-mesenchymal transition of somatic cells is proposed. Lastly, IF intensity expression varies depending on the cell type and developmental period analyzed. This article is protected by copyright. All rights reserved.