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A.V. Ramachandran, R.V. Kinariwala and R.V. Shah

Abstract

In response to the observed changes in blood during tail regeneration, a detailed histophysiological study of the haemopoietic organs such as liver, spleen and bone marrow was undertaken. During regeneration, all three organs were found to undergo histophysiological changes. Increased haemopoietic activity in the marrow and hyperplasia of the white pulp were the important changes shown by the bone marrow and spleen respectively. In the liver, the most marked effect appeared to be the formation of large numbers of lymphocytopoietic nodules. Another interesting observation was the influx and destruction of red blood cells both in the liver and spleen, once during the early regressive phase and once during the late progressive phase of regeneration. An attempt is made to correlate these changes in the three haemopoietic organs with the possible involvement of lymphocytes in the formation of a regeneration blastema and a possible haemoglobin transition during regeneration. The present observations are in concordance with the previous observations on blood.

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A.V. Ramachandran, R.V. Shah and E.P. Valsamma

Abstract

A quantitative evaluation was made of the levels of vitamin A in the liver, kidney and tail regenerate during tail regeneration in H. flaviviridis. Vitamin A in the liver increased on the first three days and decreased on the 5th day post-autotomy; a second increase was noted on the 7th day. Thereafter a subnormal level was noted on the 10th, 15th and 25th days. Vitamin A levels in the tail remained raised throughout regeneration except on the 7th and 60th days when the levels were in the normal (pre-autotomy) range. Kidney vitamin A content showed a steep increase on the 10th day while at other periods it remained in the normal range. The depletion in hepatic vitamin A content corresponded with high vitamin content in the regenerate, indicating the mobilization of this vitamin to the site of regeneration. The decreased level during dedifferentiation indicates greater utilisation of this vitamin. Supra normal levels of vitamin A in the regenerate during the blastemic and differentiation phases suggest an intimate association of this vitamin with the many events characteristic of these phases of regeneration.

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A. V. Ramachandran, M. S. Swamy and R. V. Shah

The influence of two different seasons as well as of thyroid hormone on tail regeneration in Mabuya carinata has been evaluated by measuring the rate of growth of the regenerate at various time intervals. The analysis has revealed no apparent seasonal alteration in the final length attained at the end of 60 days. However, the average per day rate of growth indicates some difference between the late non-breeding and the early breeding phases. A better growth rate was noticeable in the non-breeding phase during the first 25 days (blastemic and differentiation phases) while it was better in the early breeding phase during the last 20 days of tail regeneration (late differentiation and growth phases). These observations correlate with the differential physiological and endocrine status characteristic of the two seasons. Hypothyroidic animals showed a 71% retardation of regenerative ability as compared to euthyroidic animals, which was however rectified by thyroxine replacement. Modes of action of thyroxine on lizard tail regeneration are discussed.

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M.S. Swamy, S. Abraham and A.V. Ramachandran

Abstract

Circulating levels of serum T3 and T4 have been assayed by radioimmunoassay during tail regeneration in the gekkonid lizard Hernidacylus flaviviridis. In general the level of serum T3 was lower than that of T4; both hormones showed phase-specific alterations. The immediate post-autotomy periods (first week) were marked by elevated T4 levels; the later phases of regeneration, corresponding to peak histodifferentiation (15-40 days), were marked by elevated T3 levels. These changes in serum T3 and T4 indicate the participation of the thyroid gland in lizard tail regeneration and are discussed in relation to changes in systemic, metabolic and haematologic variables characteristic of lizard tail regeneration.