Frequency of feeding and formation of bone growth marks in frog, Rana cyanophlyctis (Schn.).

Frogs, R. cyanophlyctis (n = 45) divided into four groups, were exposed to different feeding regimens (live guppies were used as food) such as, daily, alternate day, every fourth day and weekly feeding for 5 months, during wet months of the year (April-September). Two toe clippings were made, one at the beginning and the other at the termination of the experiment. Clipped toes were demineralized, and processed for histology. In 6 out of 45 frogs one line of arrested growth (LAG) was present in the phalangeal histology at the beginning of the experiment while, at the termination of experiment 34 out of 43 frogs exhibited one LAG each indicating that in 26 frogs LAG appeared freshly during the experimental period. The fact that LAGs are formed in regularly fed frogs suggests the humid weather/seasonal rainfall may play relatively important role than the feeding in cyclic bone growth and formation of growth marks in this frog.

Effect of androgens on oviductal growth in skipper frog Rana cyanophlyctis.

Effects of exogenous androgens (testosterone, testosterone propionate and dihydrotestosterone) and estradiol-17beta on the oviductal growth/hypertrophy were studied in young and bilaterally ovariectomized (BLO) adult frogs (Rana cyanophlyctis) during postbreeding phase of the reproductive cycle. Estradiol-17beta injections induced oviductal hypertrophy to the maximal extent among hormone treated groups. In androgen treated frogs also there was an increase in the oviductal dry weight and protein content both in young and BLO adult frogs, suggesting the role of endogenous androgens in controlling the growth of oviduct in R. cyanophlyctis.

Determination of age, longevity and age at reproduction of the frog Microhyla ornata by skeletochronology.

Skeletochronological estimation of age, longevity, age at sexual maturity and breeding of Microhyla ornata was done. Frogs (n=62) were collected locally in August (rainy season) 1997 and brought to the laboratory. Body mass and snout-vent-length (SVL) of each frog was recorded; the 4th toe of both the hind limbs was clipped under anaesthesia, fixed in 10% formalin, demineralized in 5% nitric acid and processed for histology. Limb bones (femur, humerus, tibiofibula and radioulna) of 6 large sized frogs were also processed for skeletochronology in order to study the rate of resorption. Gonads of 25 frogs (belonging to different body size ranges) were processed for histology in order to ascertain the gametogenic status of individual frogs. One to four growth rings consisting of growth zones and lines of arrested growth (LAGs) were noticed in frogs of different body sizes; the number of LAGs remained identical in all the limb bones and phalanges in 5 out of 6 frogs. Back calculation indicated that the resorption rate is very low in this frog. Male frogs possessed sperm bundles in seminiferous tubules in the 1st year, while females showed yolky follicles in the ovary in the 2nd year. Frogs found in amplexus were 3 5 years old. The results suggest that this frog may live for a maximum of 5 years in the natural population.

Age related changes in ovarian follicular kinetics in the Indian skipper frog Rana cyanophlyctis (Schn.).

Changes in ovarian follicular kinetics were studied in relation to aging in the Indian skipper frog Rana cyanophlyctis. Age was determined by skeletochronology, by counting the number of growth rings and lines of arrest of growth from the cross sections of 4th phalange of 4th toe. For follicular kinetics study oocytes were counted under binocular using 10% of Bouin’s fixed ovary and they were classified into first growth phase, medium-sized second growth phase, large-sized second growth phase and atretic follicles. Analysis of phalangeal cross sections indicated that frogs ranging 14–54 g in body weight and 4·9–8·9 cm in body size showed 1–7 year rings. Frogs that weighed 14–16 g showed 1 year ring, and contained immature ovaries; those with 18 g body weight had one to two year rings, in which second growth phase oocytes appeared for the first time in the primiparous ovary. Frogs with 20–54 g body weight showed 2–5 year rings in which ovary contained 5–24% of second growth phase oocytes. Further, body weight, body size, ovarian weight, number and size of second growth phase oocytes and total number of oocytes showed a significant (P < 0·05) positive correlation, while, the number of first growth phase and atretic follicles showed a poor correlation with age. The results suggest that in nature, the age of Rana cyanophlyctis ranges between 1–7 years. Phalangeal growth rings are formed annually. Females attain sexual maturity in 2nd year. Frogs with 2–5 years of age may constitute breeding females. Body weight, body size, ovarian mass, number of second growth phase and total oocytes, and egg size increase with age up to 5 years.

Effect of synthetic nonapeptide (Thr-Cys-Ser-Val-Ser-Glu-Trp-Gly-Ile) on ovarian follicular development in the bull frog Rana tigrina (Daud).

Effect of synthetic nonapeptide (Thr-Cys-Ser-Val-Ser-Glu-Trp-Gly-Ile) representing the amino acid sequence 86-94 of human seminal plasma was studied on the ovarian follicular growth in the bullfrog R. tigrina during preparatory phase of reproductive cycle. Daily (except on Sundays) injections of 10 micrograms nonapeptide for one month caused a significant increase in ovarian weight and number of second growth phase (SGP) or vitellogenic oocytes. The results suggest that the nonapeptide is biologically active in amphibians also.