S. Oota

scure. So, in the 3rd experiment, the addition ofepinephrine as a local anesthetic during the skinbiopsy was tried, and CB, PB and Kindaly 2
were again used for fixative vehicle. At thistime, 4 mitotic LCs (Fig. 1: Rows 2, 6, 7 and 9)
were found in the materials prefixed with thefixatives in 0.05 M CB, 0.1 M PB and Kindaly 2(Table 1).
In these experiments, features observedwith a light microscope showed several characteristics (Fig. 1): i) Row 8 was the 1st mitotic
LC encountered by chance during the test for
the effect of buffer osmolarity to the cell structures, and so the serial sections and high magnification views were not taken; ii) the cytoplasm of mitotic LCs, after the metaphase to thetelophase, was clearer than that of epidermal
mature LCs and highly contrasted with theneighboring keratinocytes and the dark-stained
chromosomes, whereas the cytoplasm of LCs in
the prophase was stained at the same level asneighboring cells, or more intensely, and so thecontrast with the condensing chromatin waslow (Rows 1 and 2); iii) the serial sections indicated that each mitotic LC possessed several,
short or long, slender or podgy, cytoplasmicprocesses; iv) so in the same way, the shapes ofmitotic LCs in each section were quite different
in one cell as well as between individual cells,
even in the same mitotic phase. From the serial
sections of each row, the three-dimensional features possessing process(es) could be imaged;
and v) no round mitotic LCs were seen.
Electron microscopy showed many characteristics as follows.
Figure 2 is an electron micrograph of one of
the LCs in the prophase observed in the material
prefixed with the fixative in Kindaly 2 solution.
The intercellular space between this cell and theneighboring keratinocytes has been markedly
widened possibly due to a fixative artifact. Thismight have happened based on peculiar situations involving neighboring keratinocytes. However, the wide bases of the processes of this LC

still remain (Fig. 2A). In places, the nuclear
envelope disappeared (Fig. 2A), and spindle
microtubules passed towards chromosomes
which had begun to condense (Fig. 2Bb). LC
granules (Birbeck granules) were seen (Fig.
2Ba).
Figure 3 is one of the LCs in the metaphaseobserved in the material prefixed with the fixative in 0.1 M CB. In the row of this cell, every
section showed considerably different features.
The cell of Fig. 3A showed a relatively long andpodgy cytoplasmic process, and the cell seemed
to be just like a tadpole. Chromosomes werealigned on the metaphase plate. No centriole
was caught in the plane of this section, but at thesites regarded as the neighborhood of the poles,
parallel-arranged Birbeck granules and manyvesicular structures of various sizes were visible (Figs. 3Ba and b).
Figure 4 is one of the LCs in the anaphase.
This picture was observed in the material prefixed with the fixative in 0.05 M CB. This cellpossesses large (P) and small (p) cytoplasmic
processes (Fig. 4A). In Figs. 4Ba and b, newly
opposed segments of the nuclear envelope
appeared on the partially fused chromatin mass.
Spindle microtubules and the chromatin massformed junctions at points still devoid of the nuclear envelope. Birbeck granules were sparselyseen.
Figure 5 is one of the 2 telophase LCs. This
picture was obtained from the material prefixedwith the fixative in 0.1 M CB. Reproduced daughter LCs seemed to be separated by the invasionof the neighboring keratinocyte between thedaughter cells (Fig. 5A, double arrows). Although the nuclei of both daughter LCs showed
still young forms (Fig. 5A), their function
seemed to have become markedly active (Figs.
5Ba and b).
Through these observations, in all mitotic
phases of LCs, Birbeck granules were witnessed in the cytoplasm.

Fig. 4 (p. 207) A: A Langerhans cell (LC) in the anaphase (Fig. 1: Row 9-No. 4), × 6,000. Ba and b: Highmagnification photographs of the rectangular areas in A, × 30,000. Newly opposed segments of the nuclear
envelope have appeared on the partially fused chromatin mass. Spindle microtubules (Ba: arrowheads) andchromatin mass form junctions at points still devoid of nuclear envelope. In this section, orthogonal arranged
centrioles are seen at one side of poles (Bb: C). Birbeck granules are sparsely seen in the cytoplasm (Ba andb: arrows). Scale bar = 1 µm.

206Mitotic LCs in the normal human epidermis

Fig. 4. Legends on p. 206 (bottom).
207