Ecophysiological responses of the seminal vesicle of Libyan jird (Meriones libycus) to the Saharan conditions: histological, morphometric and immunohistochemical analysis.

Abstract

The Libyan jird (Meriones libycus) is a nocturnal Saharan Rodent submitted to a seasonal cycle of reproduction characterized by a short active period during spring and beginning of summer, and a long phase of sexual quiescence from the end of summer until the end of winter. During this cycle, the male reproductive organs, and more particularly seminal vesicles, experience some important weight and histological variations. During the breeding period, the wall of each seminal vesicle describes several folds radiating inside a broad lumen filled with a very abundant secretion. The wall is limited with high columnar epithelial cells surrounded with extracellular matrix restricted to some connnective fibres located in the narrow axis of the folds and in the chorion. The fibro-muscular wall is narrow. During sexual quiescence, the seminal vesicles regress. No secretion has been observed inside the lumen. The wall of lumen is now surrounded with a single cubic epithelium. The persistent epithelial folds possess a wide axis. The hypertrophied extracellular matrix is constituted with a very tight and abundant connective tissue. The fibro-muscular wall is thick. A quantitative morphometric study was performed with automatic image analysis that allowed to quantify the seasonal variations of the histological components. The numerical values obtained agree with the histological images observed, the epithelial surface area (microm2) is high in spring and significantly weak during sexual quiescence. The stroma and the fibro-muscular wall occupy an important surface area on sections during the resting period compared with the value collected during the active phase. The study of the apoptosis by TUNEL method revealed the presence of a considerable number of apoptotic nuclei in the epithelial fraction during the resting phase. The indirect immunohistochemical method allowed us to visualize the presence of types I and III collagen in the extracellular matrix, weak during the period of breeding, intense and diffuse during the resting season like in castrated Meriones libycus.