Evidence for tight junctions between odontoblasts in the rat incisor

Area of Science:

• Cell Biology
• Dental Research
• Histology

Background:

• Odontoblasts are crucial for dentinogenesis.
• The permeability of intercellular spaces between odontoblasts is not fully understood.
• The nature of tight junctions in odontoblasts requires clarification.

Purpose of the Study:

• To investigate the permeability of intercellular spaces between odontoblasts.
• To determine if substances can pass between odontoblasts during dentinogenesis.
• To characterize the tight junctions of mature secretory odontoblasts in rat incisors.

Main Methods:

• Perfusion of anesthetized rats with lanthanum nitrate solution.
• Electron microscopy of transverse segments of mandibular incisors.
• Analysis of lanthanum tracer distribution in interodontoblastic spaces.

Main Results:

• Lanthanum permeated 40-50 microns between odontoblasts, reaching the peripheral pulp.
• Lanthanum's passage was completely blocked by junctions at the apical ends of odontoblast cell bodies.
• Lanthanum was not detected in the predentine, indicating a barrier.

Conclusions:

• Mature secretory odontoblasts in rat incisors are connected by continuous tight junctions.
• All substances deposited in predentine and dentine must traverse through the odontoblasts.
• This finding clarifies the pathway of substance transport in dentinogenesis.