ウシガエルの背中腺 : 兩棲類孵化腺の研究第2報

概要

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The hatching enzyme, probably secreted from the dorsal gland, plays an important part in the hatching phenomena of the bull frog as observed in other amphibians. Both development and structure of the dorsal gland of the bull frog are almost the same as those of the toad. Immediately after the closure of the neural groove, cells of the neural crest above the neural tube thrust into the epithelial layer and become the dorsal gland. The glandular cells, crowding together between the nasal pits and the end of the trunk along the mid-dorsal line, soon begin to secrete. The gland reaches the summit of its development when the embryos attain 4 mm in length (7 hours before hatching) and hereafter the degenerative processes proceed gradually. But the changes are slight and most of the glandular cells remain unaffected. The cells, gradually changing their structure, continue to secrete until the end of the external-gill stage. The cells highly resemble those of the toad: they contain large vacuoles and distribute separately along the mid-dorsal line chiefly in the head region. Then, the degenerative proceses are accelerated suddenly and the glandular cells begin to diminish considerably in size. In the larvae of 10 mm in length (12 days after hatching), in which both of the external gills have disappeared, there remains no trace of the dorsal gland.
社団法人日本動物学会の論文
1951-06-15