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.

Epididymal protein secretion and its androgenic control in wall lizards Hemidactylus flaviviridis (Ruppell).

The total protein level in different segments of epididymis of normal lizard exhibited noticeable increase from early February to late March of a same reproductive phase. Comparison among the protein level of different epididymal segments showed insignificant variation from anterior to posterior part in early February but in late March, the protein level in posterior segment was appreciably higher than in anterior and middle segments. Further, testosterone-induced epididymal protein did not exhibit any significant quantitative variation among different regions. The electrophoretic pattern of luminal fluid from different epididymal regions of normal lizard showed 28 protein bands without any marked regional difference. However, only 16 protein bands could be demonstrated in the epididymal fluid of any region. Unlike molecular size, isoelectric focussing of testosterone induced epididymal proteins revealed that three regions of epididymis differ in their nature of protein. The number of proteins having alkaline pH range in anterior and middle regions were 4 and 3, respectively which increased upto 6 in posterior region.