| Autor: |
Delfino, G., Brizzi, R., Calloni, C. |
| Předmět: |
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| Zdroj: |
Acta Zoologica; Jan94, Vol. 75 Issue 1, p27-36, 10p, 27 Diagrams, 1 Chart |
| Abstrakt: |
The morphological evolution of the cutaneous venom during ontogenesis in the tree-frog Hyla arborea arborea is described using light and electron microscopy. Venom biosynthesis involves the rough endoplasmic reticulum and Golgi stacks. The secretory product first appears at the hind-limb larval stage in the form of aggregates of small granules or larger, more elaborate structures both contained in Golgi stacks. Maturative evolution proceeds through the merging of these secretion storage bodies and leads to the remarkable morphological heterogeneity characteristic of the venom of premetamorphic larvae and juveniles. However, large structures, resulting from the aggregation of small granules arranged in a repeating pattern become the only secretory accumulation bodies found in fully developed glands. In juveniles, discrete amounts of venom were seen to be discharged through exocytosis into the exiguous gland lumen which lies just beneath the intercalated tract. These findings strongly contrast the traditional pattern of holocrine release characteristic of anuran serous glands. The merocrine release of tiny venom particles is consistent with the regulative roles—relevant to the skin physiology—performed by component molecules of anuran cutaneous venoms. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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