Plate 15.

Figure 18. Excised submandibular gland rudiments from 13-day (above left) and 14-day (right) C3H/Bi embryos. Epithelial portions of rudiments are light, sharply circumscribed structures surrounded by darker capsular mesenchyme. Sublingual gland rudiment is also present at lower right of 14-day submandibular rudiment. Unstained, fresh specimens. X 90.

Figure 19. Appearance of 14-day submandibular rudiment after 5 days in tissue culture. Note extensive development of adenomeres. Duct is mildly dilated. Unstained living culture. X 50.

Excised submandibular gland rudiments from 13 dayAppearance of 14 day submandibular rudiment after 5 days in tissue culture

Plate 16

Figure 20. Histologic appearance of submandibular gland rudiment freshly excised from 13-day-old C3H/Bi embryo. Stalk has been transected at right. Cells of epithelial portion show no differentiated features at this time. Hematoxylin and eosin. X 475.

Figure 21. Histologic appearance of submandibular gland rudiment freshly excised from a 14-day-old C3H/Bi embryo. Terminal swellings of a bifurcating branch of the epithelial rudiment are shown surrounded by capsular mesenchyme. Many mitoses present in the still undifferentiated epithelium. Hematoxylin and eosin. X 520.

Histologic appearance of submandibular glandHistologic appearance of submandibular gland rudiment

Plate 17

Figure 22. Submandibular rudiment from 13-day C3H/Bi embryo, after 17 days in culture. Not infected with polyoma virus. Development is limited in this example to formation of several branching tubular structures (upper left and right) extending out from dilated duct (lower center). Epithelium and mesenchyme are in good viable condition. Living culture. X 90.

Figure 23. Culture identical with that shown in figure 22, but infected with polyoma virus at time of isolation. Epithelial development was similar in degree to that in figure 22 before viral effects appeared. Epithelium obscured by extensive necrosis of mesenchyme. X 90.

Submandibular rudiment from 13 dayCulture identical with that shown in figure 22

Plate 18

Figure 24. Thick section of 13-day submandibular rudiment after 9 days in uninfected tissue culture. Tubular epithelial structures have branched from original bud. No necrosis of epithelium or mesenchyme. Hematoxylin and eosin. X 520.

Figure 25. Thick section of 13-day submandibular rudiment after 9 days in polyoma virus-infected culture. Slightly to right and above center, nucleus of mesenchymal cell contains inclusion body. Debris from lysed cell is adjacent to it, on left. Nuclei of other mesenchymal cells (center- and lower-right) show vacuolar changes. Hematoxylin and eosin. X 780.

Thick section of 13 day submandibular rudimentThick section of 13 day submandibular rudiment after 9 days

Plate 19

Figure 26. Section of dilated ductal portion of 14-day submandibular rudiment after 12 days in polyoma virus-infected culture. Several epithelial cells show amphophilic intranuclear inclusions. Others show nuclear vacuolation (below). Hematoxylin and eosin. X 780.

Figure 27. Control culture of 14-day submandibular rudiment after 12 days. No epithelial or mesenchymal changes. Hematoxylin and eosin. X 315.

Section of dilated ductal portion of 14 day submandibular rudimentControl culture of 14 day

Plate 20

Figure 28. Section of 14-day submandibular rudiment after 22 days in culture, not infected with polyoma virus. Note well-advanced morphogenesis and good viability, although ducts (left) are dilated. Hematoxylin and eosin. X 200.

Figure 29. Section of culture similar to that shown in figure 25, but infected with polyoma virus at time of explantation. Note necrosis of mesenchyme and intranuclear lesions in epithelium at upper right. Hematoxylin and eosin. X 200.

Section of 14 day submandibular rudiment after 22 days in cultureSection of culture similar to that shown in figure 25

Plate 21

Figure 30. Higher magnification of area from section shown in figure 28. Viable epithelium and mesenchyme. Hematoxylin and eosin. x 610.

Figure 31. Higher magnification of area from section shown in figure 29. Necrosis of mesenchyme in upper left. Nucleus of mesenchymal cell above and to right of center contains irregular amphophilic bodies. Compare epithelial nuclear characteristics with those of epithelium in figure 30. Tubular pattern is partially disrupted. Portion of mitotic figure present in epithelial cell at lower left. Hematoxylin and eosin. x 610.

Higher magnification of area from section shown in figure 28Higher magnification of area from section shown in figure 29

Plate 22

Figure 32. Uninfected gelatin-sponge control culture of 14-day submandibular rudiment 27 days after explanation. Portion of duct is on right, tubular epithelial structures on left. Compare with figure 33. Hematoxylin and eosin. X 420.

Figure 33. Culture similar to that shown in figure 32, but infected with polyoma virus at time of explanation 27 days previously. Note marked nuclear changes of ductal (center) as well as of tubular epithelium (right), with much necrosis in former. Squamous epithelium on left is probably from buccal epithelium included with rudiment during excision. Hematoxylin and eosin. X 420.

Uninfected gelatin sponge control culture of 14 day submandibular rudimentCulture similar to that shown in figure 32

Plate 23

Figure 34. Section of another gelatin sponge matrix culture of 14-day submandibular rudiment infected with polyoma virus and carried in culture for 27 days. Note (lop) altered epithelium with large nuclei and nucleoli, and intranuclear vacuolation. Hematoxylin and eosin. X 420.

Figure 35. Higher magnification of altered epithelium in another area of section shown in figure 34. Mitotic figure is present among altered epithelial cells. Hematoxylin and eosin. X 1500.

Section of another gelatin sponge matrix cultureHigher magnification of altered epithelium