Ultrastructural observations on the development of the human conjunctival epithelium.

In human embryos with a gestation age of 8.6-22 weeks, the palpebral conjunctival epithelium was examined by transmission electron microscopy (TEM). During the gestation period studied, the structural integrity of the tissue is established by an increase in the quantity of tonofilaments, desmosomes, and hemidesmosomes as well as by the undulating appearance of the cell membranes, the widening of the intercellular space, and the development of cytoplasmic protrusions into it. The superficial cells display a chronological sequence in the elaboration of transport mechanisms. A precursor stage is described for hemidesmosome formation at the interface between the basal cell membrane and the conjunctival stroma.