The Herpetological Journal

pp.276-279

Authors: A. D Padhye And H. V. Ghate

Abstract: Short term effects of altered pH on embryos and tadpoles of the frog Microhyla ornata were studied under laboratory conditions. Alterations in pH were made by using dilute hydrochloric acid and sodium hydroxide solutions.
Late gastrula stage embryos tolerated pH between 4 to 1 0.5, showing normal development and hatching. At pH 3 and below development was immediately arrested and the embryos were killed within a few hours. Between pH 3.2 and 3.6 there was gradual decrease in toxicity, however, development was often arrested at about tail-bud stage. At pH 3.8 there was only 20% mortality while survivors showed normal development. In alkaline range, the maximum pH tolerated without any apparent ill effect on development and hatching was about 1 0.5. At pH 1 1 .0 and above there was drastic effect on the embryos which caused immediate cell to cell disaggregation of the embryos within an intact vitelline membrane.
The effects of altered pH, especially acidic pH, were similar to those observed earlier with sodium chloride treatment. In either cases normal swelling of the embryonic perivitelline space was prevented. There was no significant difference in the tolerance of the tadpoles to altered pH as compared to that of the embryos, however hind-limb stage tadpoles appeared to be slightly resistant to acidic pH and slightly more sensitive to alkaline pH .