Interrelationship among testicular cells in wall lizard Hemidactylus flaviviridis (Rüppell): an ultrastructural seasonal and experimental study.

The present study was aimed at investigating ultrastructure of different testicular cells and their interactions through various junctional specializations during different phases of reproductive cycle in wall lizard H. flaviviridis to develop an integrated approach of cell-cell interaction in control of testicular functions. Specialized steroid synthesizing cell organelles such as smooth endoplasmic reticulum (SER) and long slender mitochondria with tubulo-vesicular cristae were predominantly seen in Leydig as well as Sertoli cells during spermatogenically active phase, suggesting their active involvement in steroid biosynthesis. Peritubular cells also exhibited marked seasonal variations. Multi-layered fibroblast-like peritubular cells during regressed phase became single layered myoid-like during spermatogenically active phase. The presence of various types of junctions, including gap and tight junctions (occluding junctions) and adhering junctions such as desmosomes, septate-like junction, ectoplasmic specializations and tubulo-bulbar complexes, were demonstrated among testicular cells in wall lizard H. flaviviridis. However, the nature and degree of junctional (environmental) interaction varied with the reproductive state of the wall lizard. Further, administration of dihydrotestosterone in wall lizards during regressed phase resulted in increase of lipid droplets in Leydig cells and accumulation of germ cell debris in seminiferous tubules. Some of the Sertoli cells were seen darker in response to testosterone treatment probably due to its inhibitory effect on lipid metabolism. These results suggest that testosterone either directly or via inhibiting pituitary basal gonadotropin secretion has suppressive effect on testicular cells.

Significance of regional difference in ion concentrations in lizard, Hemidactylus flaviviridis (Rüppell): assessment of ionic influence on sperm motility in vitro.

A gradual increase in the concentration of Ca2+ from anterior to the posterior region was observed when mono- and divalent cations were estimated in different segments of the epididymis in wall lizard. Na+ and K+ levels increased from anterior to middle segment but declined significantly in the posterior segment. However, no significant difference in the levels of Mg2+ was observed in various segments. To study the influence of mono- and divalent cations on sperm motility in vitro, the spermatozoa from posterior region of the epididymis were incubated in medium with varying concentrations of Na+, K+, Ca2+ and Mg2+. Spermatozoa were non-motile when suspended in Na+-free medium. Addition of NaCl induced the acquisition of sperm motility in a concentration-dependent manner. Further, amiloride, a Na+-influx blocker, markedly reduced the Na+-induced forward progressive motility. Unlike Na+, the presence of K+ or Ca2+ in the incubation medium reduced the motility of spermatozoa even at very low concentrations. The inhibitory effect of Ca2+ decreased when nifedipine, a Ca2+-influx blocker, was added to the medium. Mg2+ at high concentrations only was able to reduce the forward progressive motility.