A study of the spore wall of Encephalitozoon hellem was performed on thin sections, freeze-fracture, and deep-etched samples to obtain information on spore wall organization and composition. Our observations demonstrate that the spore wall is formed by an inner 30-35 nm electron-lucent endospore and an outer 25-30 nm electron-dense exospore. The exospore is a complex of three layers: an outer spiny layer, an electron-lucent intermediate lamina and an inner fibrous layer. Freeze-fracture and deep-etching techniques reveal that the intermediate lamina and the inner fibrous layer result from the different spatial disposition of the same 4-nm thick fibrils. In thin sections the endospore reveals a scattered electron-dense material that appears in the form of trabecular structures when analyzed in deep-etched samples. The presence of chitin in the exospore is discussed.

Study of biopsy specimens of a man with 'decapitated' spermatozoa indicated that the malformation was due to an overproduction of a membraneous vesicles system by the Golgi complex in the region between the centrioles and acrosome during the spermatid stage. The tails were almost normal in structure and 50% were motile in the ejaculate although few followed a straight trajectory.

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