**3.1 Autofluorescent microcrystalline silica (chalcedony)**

Adult female and male *P. extenta* were collected from Bahía Blanca Estuary in Buenos Aires Province, Argentina. Fractionation of electric tissue homogenates by differential centrifugation was carried out as described in Section 2.1.

Fractions (nuclear fraction "N"; microsomes "P" and supernatant "S") were used and observed with a LSCM. A nuclear fraction shows many autofluorescent crystals and also little electrocytes, Fig. 3. Electrocytes from the electric organ of the Patagonian ray *Psammobatis extenta* are very unusual cells: semicircular in shape, multinucleated and highly polarized. Their anterior face is concave and innervated by numerous nerve-endings.

Fig. 3 shows an unbroken electrocyte with many autofluorescent crystals, these were observed with an argon ion laser with emission band at 488 nm (green). This image was merged with (DIC).

Normally, the microsomal fraction contains membranes from the synaptic region. The microsomal fraction has many autofluorescent crystals. A crystal of chalcedony from the microsomal fraction, its dimensions and autofluorescent intensity (I, arbitrary units) are

The Growth of Chalcedony (Nanocrystalline Silica) in Electric Organs from Living Marine Fish 291

Fig. 4. An autofluorescent crystal of chalcedony from the microsomal fraction in LSCM.

Fig. 5. Images of a chalcedony crystal from the microsomal fraction in LSCM.

Fig. 3. Photomicrograph of a nuclear fraction of the electric organ from *P. extenta* in LSCM. This fraction shows a little electrocyte, which is unbroken. Many autofluorescent crystals were observed in the electrocyte with an Ar ion laser with emission band at 488 nm (green). This image was merged with DIC.

shown in Fig. 4. This image was obtained with an argon ion laser with emission band at 488 nm (green). This crystal is about 20 micron.

The crystal dimension and autofluorescent intensity (I) are shown in this image. This crystal was observed by using an argon ion laser with emission band at 488 nm (green).

Images of a chalcedony crystal from the microsomal fraction in LSCM are shown in Fig. 5.

Crystals from this fraction are rhombohedral in shape and they are in large quantities. This crystal is about 20 micron. The chalcedony crystal has autofluorescence with different ion lasers and is about 20 micron. A He/Ne ion laser with emission band in 543 nm (red), a He/Ne ion laser with emission band in 633 nm (blue) and an Ar ion laser with emission bands in 458 nm (cyan), and 514 nm (yellow) were used. An image DIC of the crystal is shown (top, right side) and also all the images merged (botton, right side).

Fig. 3. Photomicrograph of a nuclear fraction of the electric organ from *P. extenta* in LSCM. This fraction shows a little electrocyte, which is unbroken. Many autofluorescent crystals were observed in the electrocyte with an Ar ion laser with emission band at 488 nm (green).

shown in Fig. 4. This image was obtained with an argon ion laser with emission band at 488

The crystal dimension and autofluorescent intensity (I) are shown in this image. This crystal

Images of a chalcedony crystal from the microsomal fraction in LSCM are shown in Fig. 5. Crystals from this fraction are rhombohedral in shape and they are in large quantities. This crystal is about 20 micron. The chalcedony crystal has autofluorescence with different ion lasers and is about 20 micron. A He/Ne ion laser with emission band in 543 nm (red), a He/Ne ion laser with emission band in 633 nm (blue) and an Ar ion laser with emission bands in 458 nm (cyan), and 514 nm (yellow) were used. An image DIC of the crystal is

was observed by using an argon ion laser with emission band at 488 nm (green).

shown (top, right side) and also all the images merged (botton, right side).

This image was merged with DIC.

nm (green). This crystal is about 20 micron.

Fig. 4. An autofluorescent crystal of chalcedony from the microsomal fraction in LSCM.

Fig. 5. Images of a chalcedony crystal from the microsomal fraction in LSCM.

The Growth of Chalcedony (Nanocrystalline Silica) in Electric Organs from Living Marine Fish 293

This chalcedony crystal was observed by using an argon ion laser with emission band at 488 nm (green). This crystal is about 10 μm. This fraction has many little autofluorescent

The same crystal of chalcedony (from Fig. 7) is shown in 3D images, Fig. 8. An argon ion

Fig. 7. A crystal of chalcedony from the microsomal fraction in LSCM. An argon ion laser was used, with emission bands in 458 nm (cyan) and 514 nm (yellow). Emissions were

Fig. 8. 3-D images of the silica polymorphs from the microsomal fraction in LSCM .

crystals.

merged and contrasted with DIC.

The chalcedony crystal has autofluorescence with different ion lasers: a He/Ne ion laser with emission band in 543 nm (red); a He/Ne ion laser with emission band in 633 nm (blue); an Ar ion laser with emission bands in 458 nm (cyan), and 514 nm (yellow) were used. An image DIC of the crystal is shown and also all the images merged (right side, top and botton). This crystal is about 20 μm in size.

An image of a chalcedony crystal from the supernatant fraction in LSCM is shown in Fig. 6, it was observed by using an argon ion laser with emission band at 488 nm (green). The chalcedony crystal has autofluorescence with different ion lasers and is about 10 micron in size. The supernatant fraction has many crystals.
