The extracellular matrix between the optic vesicle and presumptive lens during lens morphogenesis in an anophthalmic strain of mice.

Extracellular matrix material present during early lens morphogenesis in anophthalmic strain ZRDCT-Ch mice was studied histochemically by the Alcian blue 8GX pH 2.5, Alcian blue 8GX pH 2.5/periodic acid-Schiff combined, high iron diamine, and Van Gieson methods. Observed staining patterns were compared with results from an analysis of a normal strain of mice (E.H. Webster, Jr., A.F. Silver, and N.I. Gonsalves, 1983, Develop. Biol. 100, 147-157). No differences in constituents were found between the strains in staining patterns of the ectodermal basal lamina. However, the optic vesicle basal lamina in the anophthalmic strain was found to have a relatively lower staining intensity for sulfated glycosaminoglycan associated with it than was observed in the normal strain, although these mutant optic vesicles were morphologically normal. Results from this and the earlier study on normal mice indicate that one function of sulfated glycosaminoglycan in early lens morphogenesis may be to serve as a cementing medium between the optic and lens rudiments. This sulfated glycosaminoglycan deficiency on the anophthalmic optic vesicle basal lamina is temporally correlated with and may be causally related to precocious lens cup formation and frequently observed separation of the normally adherent eye rudiments. Conclusions drawn from this study are consistent with the speculation of H.B. Chase and E.B. Chase (1941, J. Morphol. 68, 279-301) that there may be abnormal contact between the optic vesicle and presumptive lens ectoderm in the mutant strain, although there is a differing view on the cause of the abnormal contact.

Histochemical analysis of extracellular matrix material in embryonic mouse lens morphogenesis.

Extracellular matrix material (ECM) present during mouse lens morphogenesis was studied histologically by the periodic acid-Schiff, Alcian blue 8GX, pH 2.5, high iron diamine, and Van Gieson methods, and enzymatically with bovine testicular hyaluronidase, Streptomyces hyaluronidase, malt diastase, and collagenase. The basal lamina of the optic vesicle prior to lens placode formation was found to be higher in glycosaminoglycan (GAG) content than was the ectodermal basal lamina. Upon apposition of the optic vesicle and presumptive lens ectoderm, the ECM plus basal laminae appeared as the equivalent of adding both optic vesicle-associated and ectodermal-associated basal lamina. The proposal is made that the initial triggering mechanism of lens morphogenesis consists of a cross-linking and polymerization of optic vesicle-associated GAG to ectodermal-associated glycoproteins resulting in a firm attachment between the structures. Basal lamina associated with the presumptive pigmented retina and also the more ventral part of the interface matrix were found to change from predominantly GAG in early stages to collagen deposits in more advanced stages, temporally coinciding with the appearance of differentiative markers in each structure. This pattern of GAG turnover and replacement by collagen during the course of development is also seen in mouse salivary gland morphogenesis (M. R. Bernfield, S. D. Banerjee, and R. H. Cohn (1972). J. Cell Biol. 52, 674-686.).

Wound healing in X-irradiated mammalian skin.

Certain parameters of wound healing were investigated in mouse skin given 950 rads and 3325 rads of X-irradiation at various times relative to wounding. Increased inflammation, delayed dermal regeneration, and delayed contraction were noted in all irradiated groups. The activation of surrounding hair follicles, a process that usually accompanies wounding in mouse skin, occurred earlier, over a shorter elapsed time, and over a greater area of skin in animals irradiated prior to wounding than in the controls or in those irradiated and wounded simultaneously. Epidermal mitotic activity in wounds made at the time of irradiation was initially depressed but recovered by the second postoperative day. Wounds in pre-irradiated animals gave an unexpected result. They responded with an immediate burst of mitotic activity without the usual 24-hr lag that was seen in controls. In the pre-irradiated specimens a substantial number of cells appeared to die after dividing.