Quarterly Journal of Microscopical Science, Vol s3-91, 79-88, Copyright © 1950 by Company of Biologists

Cytochemical Studies on the Embryonic Development of Drosophila melanogaster

II. Alkaline and Acid Phoshatases

¹ Institute of Animal Genetics, Edinburgh; Dept. of Biology, National University of Che-Kiang, Hangchow, China

1. Drosophila ovary and testis are very rich in acid phosphatase, but contain no histochemical trace of alkaline phosphatase. Thus the mature oocyte shows a strong acid phosphatase reaction both in the nucleus and cytoplasm. Sperm heads are equally reactive.

2. Acid phosphatase is demonstrable in Drosophila embryos from early cleavage up t6 the hatched larva. No striking change in enzyme activity has been observed during this period.

3. Alkaline phosphatase is not detectable in the first half of embryonic life. It suddenly appears in the ventral ectoderm near the future thorax during or shortly after the contraction of the germ band. The enzyme activity then spreads to the other parts of the embryo following definite patterns, until finally the whole embryo becomes active. The possible mechanism of the spreading of enzyme activity is discussed.

4. Alkaline phosphatase disappears in most tissues before hatching, but is retained in the gut epithelia, salivary glands, and Malpighian tubes. The relationship of this enzyme to histo-differentiation is suggested.

5. The centre of origin of alkaline phosphatase activity is considered as the ‘differentiation centre’ of the Drosophila embryo.

6. The high cytoplasmic acid phosphatase activity of the oocyte and nurse cells and a similar activity of the yolk in the developing embryos indicate that the enzyme plays some role both in the synthesis and in the degradation of yolk.