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We investigated the differential distribution of basement membrane type IV collagen a chains in the mouse brain by immunohistochemistry using a chain-specific monoclonal antibodies. Subendothelial basement membranes were found to contain alpha1 and alpha2 chains. Basement membranes surrounding smooth muscle cells on blood vascular walls were immunoreactive for alpha1 and alpha2 chains but not for alpha5 and alpha6 chains. Interestingly, the pia mater contained a thin basement membrane which was positive for alpha1, alpha2, alpha5, and alpha6 chains, suggesting that glia limitans superficialis coheres basement membranes containing [alpha1(IV)]2alpha2(IV) and [alpha5(IV)]2alpha6(IV) molecules. In contrast, capillaries always possessed thin basement membranes of [alpha1(IV)]2alpha2(IV) molecules. Cerebrospinal fluid is produced through filtration of blood at the choroid plexus, where two distinct basement membranes were detected by anti-al and anti-alpha2 antibodies. The subendothelial basement membrane appeared to consist of [alpha1(IV)]2alpha2(IV) molecules, whereas the subependymal basement membrane in the choroid plexus was strongly positive for alpha3, alpha4, and alpha5 chains, indicating that the filtering unit was composed of alpha3(IV)alpha4(IV)alpha5(IV) molecules. That the specific localizations of these molecules are shared by renal glomeruli and the choroid plexus leads us to hypothesize that the supramolecular network containing alpha3(IV) alpha4(IV)alpha5(IV) molecules may function as a permeability selective barrier.

The structure-function relationships of the macaque extensor digitorum and hallucis brevis muscle (EDB and EHB), the single intrinsic and four-tendoned muscle of the dorsum of the foot, were investigated in the macaque after preparation of samples by two plastination methods, using gelatin and epoxy resin. These preparative methods clearly revealed the muscle fibers, spindles and myelinated axons in the EDB and EHB. In the more medially located two bellies (the medial two bellies of the EDB), the mean relative proportion of red fibers was larger than in the more laterally located two bellies (the lateral belly of the EDB, and the EHB), while those of intermediate and white fibers were smaller than in the more laterally located two bellies. (The difference was significant between some pairs of bellies.) In the more medially located two bellies, the mean cross-sectional area of each type of fiber, namely, the white, intermediate and red fibers, tended to be smaller than in the more laterally located two bellies. (There were significant differences between many pairs of bellies.) The total number of muscle spindles within an EDB and EHB was 15, and larger numbers of muscle spindles were distributed to the medially located two bellies compared to the laterally located two bellies. (There were significant differences between many pairs of bellies.) These results suggest that the more medially located two bellies of the EDB and EHB are adapted to the relatively precise movements of toes, while the more laterally located two bellies are adapted to the prompt extension and abduction that are related to the arboreal habitat of the macaques.

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