[Intracytoplasmic desmosome in squamous cancer cells of the lung in man]

Ultrastructure of intracytoplasmic (cytoplasmic) desmosomes in the squamous cancer cells of the human lung was studied by electron microscopy. In 17 cases of non-keratosic squamous cell carcinoma of the lung, intracytoplasmic (cytoplasmic) desmosomes were found in 4. In contrast to what previous investigators had proposed that the intracytoplasmic desmosomes are formed by cell fusion with the membrane being deep in the cell and cell digestion under the diffusion of hydrolytic enzymes, our result indicates that the intracytoplasmic desmosomes might be a structure formed by cell intima system itself during cell division. The structure suggests that the desmosomes originate from the cell intima system.

Purification and primary structures of duck fibrinopeptides A and B

Duck fibrinopeptides A and B were purified by Dowex 50 W X 2 ion exchange resin and DEAE-Sepharose CL-6B. The complete primary structures of duck fibrinopeptides A and B were determined by manual Edman Sequence determination. The primary structure of duck fibrinopeptide A is pyr. Asp. Gly. Lys. Ser. Ser. Phe. Gln. Lys. Glu. Gly. Gly. Gly. Val. Arg., and that of duck fibrinopeptide B is Pyr. Ala. Ser. Thr. Asp. Tyr. Asp. Asp. Glu. Asp. Glu. Ser. Thr. Val. Pro. Glu. Ala. Arg.

Transformation of ultrastructural type of fast-twitch muscle fibres after cross-innervation by tetrodotoxin-blocked slow muscle nerve

It is shown in rats that cross-innervation of the fast-twitch muscle extensor digitorum longus (EDL) by the nerve of the slow-twitch muscle soleus (SOL) can cause a complete transformation of the Z-band width from the fast to the slow muscle fibre type within two weeks and that it can still induce such a transformation, though usually less completely, even when impulse activity is excluded by chronical tetrodotoxin (TTX) block of the nerve. This provides a piece of clear-cut evidence for the presence of some activity-independent trophic factor in the neural determination of skeletal muscle fibre type.