Cytoplasmic annulate lamellae in human spermatogenesis.

Electron microscopic examination of normal human testicular tissue revealed annulate lamellae (AL) in the cytoplasm of primary spermatocytes and spermatids. AL of primary spermatocytes are encountered in the perinuclear region, parallel to the nuclear envelope and form single or multiple membranous profiles containing numerous annuli (500-600 A in diameter) frequently associated with a fibrillar electron dense material. Spermatids contain numerous layers of AL either continuous with the nuclear envelope and caudal to the acrosome or peripherally positioned in the cytoplasm. Individual lamellae possess terminal dilations and display continuities with the endoplasmic reticulum. The interlamellar space in spertmatid AL is entirely filled with a fine granular electron dense material. Additionally, the breakdown of AL in spermatozoan residual bodies is indicated by a dilation of AL cisternae to form vacuoles following the dissolution of pore complexes.