[Glands in the skin of the fire-bellied toad (Bombina bombina(L.); Discoglossidae, Anura): type, number, size and distribution under natural and experimental conditions].
In the skin of the fire-bellied toad (Bombina bombina) 5 types of glands are found. By analogy with the comparable glands of the yellow-bellied toad and the grass frog, these are called the toxic, lumpy, mucous, callous, and small glands. The callous glands were omitted from the present study. 2. Lumpy glands are most numerous in the middle of the back of the fire-bellied toad, their numbers decreasing progressively over the sides to the middle of the ventral surface. Mucous glands are more common cranially than caudally. The toxic and small glands are uniformly distributed over the body. 3. On the average there are 700 glands per square cm of skin in the fire-bellied toad. Of these, in the male the lumpy glands represent less than 10%, while the toxic, mucous and small glands each account for 30%. In the females 50% of the total number of glands are mucous glands, and only about 10% toxic glands; lumpy and small glands occur in the same proportions as in the males. Following gonadotropin injection, no change in the number of glands was observed in the male. 4. The largest toxic and lumpy glands are located cranially; toward the tail their size is reduced. The mucous glands have the greatest volume on the sides of the body. Small glands are of similar size everywhere. 5. Glands of uniform size are arranged in longitudinal rows on this toad. The dorsally situated toxic, lumpy and mucous glands are larger, on the whole, than the more ventral glands of the same types. 6. All 4 gland types on the body of Bombina are larger in males than in females. 7. Following administration of PMS to the male there is a selective increase in volume of the toxic and lumpy glands on the dorsal surface, but no corresponding increase on the ventral surface. Mucous and small glands do not change in size after hormone treatment. 8. The capacity of all the glands in a cm2 of skin, in terms of mean volume, is 1.7 mm3 in males not treated with hormones. After PMS treatment of the male the gland volume per cm2 increase to 2.5 mm3. The total volume per cm2 in females is only 0.65 mm3.