The epididymis of the male reproductive system is known to be involved in sperm maturation via the production of polypeptides, glycoproteins, surface proteins, enzymes and other factors. During the annual reproductive cycle, the epididymis of the lizard Eutropis carinata undergoes dramatic changes, both morphologically and biochemically, that occur in a well-organized sequence. The present study reveals the sequential changes that occur in the production and concentration of proteins in the epididymal luminal fluid throughout the annual reproductive cycle. A one-dimensional electrophoretic profile of the epididymal luminal proteins revealed a total of 18 bands in the regenerative phase, 22 bands during breeding and 17 bands in the post-breeding as well as regressed phases of the reproductive cycle. By two-dimensional electrophoresis, the protein complexes that are unique to the breeding phase were further resolved based on their pI and the molecular weight of each protein of the protein complex was determined. This is the first study to observe that proteins that are present during the reproductively inactive phase disappear during the reproductively active phase. The Periodic Acid Schiff (PAS) test for protein profiles revealed the presence of proteins with a carbohydrate moiety. Certain enzymes, such as acid phosphatase, alkaline phosphatase, and α-glucosidase, are highly sensitive to seasonal changes and their activity parallels the production of the epididymal proteins. This study provides evidence for androgen-dependent cyclical changes in the pattern of protein profiles and enzyme activity of the epididymal lumen in the lizard E. carinata.

We studied seasonal variation of the secretory granules in the epithelial cells of the sexual segment of the kidney (SSK) during the annual sexual cycle in the lizard, Eutropis carinata using light and electron microscopy in correlation with measurements of androgen levels. During the breeding phase, the epithelium of the SSK consists of simple columnar cells with basal nuclei. The cytoplasm contains numerous eosinophilic secretory protein and carbohydrate granules, but lacks glycosaminoglycans. These secretory granules develop during the regenerative phase when the circulating testosterone level increase. During the breeding phase, when the circulating testosterone levels are high, three types of secretory granules can be differentiated in the cytoplasm based on size and opacity; electron translucent type I, electron dense type II, and biphasic type III granules. Type II granules are found at various stages of maturity and degeneration/utilization. All types of secretory granules are released through an apocrine process. Microvilli and tight junctions are prominent at the apical portion of the cell. The cytoplasm contains, Golgi complexes, an abundant network of rough endoplasmic reticulum, numerous tubular mitochondria, condensing, mucus filled and empty vacuoles. Intercellular canaliculi are narrow and indistinct during the regenerative and breeding phases, respectively. During the regressed phase, when the circulating testosterone levels are lowest, the cells are found regressed with wide intercellular canaliculi and devoid of secretory granules. Then the cytoplasm contains a few round mitochondria, Golgi and scanty endoplasmic reticulum.

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