CONNEXINS IN THE DEVELOPING SALIVARY-GLANDS

Freeze-fracture and immunohistochemistry were used to elucidate the ul trastructure of gap junctions and the expression of connexins (gap jun ction structural proteins) Cx32 and Cx43 in the developing rat submand ibular glands. Developing rat submandibular glands were examined from the 17th gestational day to the 14th day after birth. Gap junctions co uld be observed as clusters of particles 9-12 nm in diameter during th e gestational days. The junctions were very small and consisted of abo ut 20 particles in a relatively regular arrangement with a wide center -to-center spacing of 15-18 nm on the PF face. Fluorescence spots reac ting positively to Cx33 were found between glandular cells from the 17 th gestational day. Very few spots positive to Cx32 could be detected during gestation, their numbers: increasing after birth. The possibili ty that Cx32 may have a role in the establishment of secretory regulat ion and that Cx43 is associated before birth with glandular growth and differentiation is discussed.