Pre‐Sertoli Cells: A Light And Electron Microscopic Study

Abstract

INTRODUCTION Sry gene expression, starting at 10,5dpc, initiates male sex determination. Sry gene initiates testis differentiation by regulating the differentiation of precursor supporting cells not into Granulosa cells but Sertoli cells (1). Pre‐Sertoli cells are the first cell type to show sex differentiation in gonads. This study aimed to observe the light and electron microscopic features of pre‐Sertoli cells. MATERIAL AND METHODS In this study 27 embryos obtained from 6 balb/c type pregnant female mice from 11,5 to 12,5 dpc were used. Sections were observed by using light and electron microscope. RESULTS Pre‐Sertoli cells, stained with PAS, were seen as forming a cord around germ cells starting from central parts of gonads (Fig.1). Germ cells and epithelial cells lining the gonadal ridge were PAS (‐). On electron microscope pre‐Sertoli cells were seen mostly disorderly but also clustered and encircled the germ cells at some parts. The nuclei of pre‐Sertoli cells were pulled at one pole of the cells. The cytoplasm at the other pole consisted of granuler and smooth endoplasmic reticulum, ribosomes, Golgi apparatus, mitochondria and large amount of glycogen granules (Fig. 2). Lipid granules were also seen in cytoplasm. DISCUSSION Pre‐Sertoli cells are found disorderly in gonadal ridges as they are first developed. Shortly after that they proliferate and cumulate to form circular cords around germ cells (2). The accumulation of glycogen starting in pre‐Sertoli cells is responsible for PAS(+) staining. The in vitro study of Matoba et al. stated that, testis specific accumulation of glycogen is a tissue‐otonomous event as it is possible even with no serum or in the absence of adjacent mezonephrosis(4). The same study puts forward that the activation of PI3K‐AKT pathway after Sry gene expression enhances glycogen accumulation in pre‐Sertoli cells. Sox9, Mis, Dhh, Fgf9 are reported as pre‐Sertoli cell marker genes(3). By using the fact that pre‐Sertoli cells are stained PAS(+) because of glycogen they use as energy resource, it can easily be determined if the gonad is developing as male or female, before it is seen morphologically at 12,5dpc.