CONNECTIONS BETWEEN THE VARIOUS ELEMENTS OF THE CIS-COMPARTMENTS AND MID-COMPARTMENTS OF THE GOLGI-APPARATUS OF EARLY RAT SPERMATIDS

Background: The exact structural relationships of the saccules, membra nous tubules, and vesicles that compose the cis- and mid-compartments of the Golgi cortex of rat spermatids was investigated to determine th e relationship of these elements to each other. Methods: Tissues fixed with glutaraldehyde and buffered in sodium cacodylate were examined w ith the electron microscope. Electron micrographs, including stereopai rs, were analyzed to determine the three-dimensional organization of t he Gels elements. Results: The deeper layer of the Golgi cortex was co mposed of stacks of saccules connected to each other either by saccule s or membranous tubules. The peripheral region of the Golgi cortex, lo cated between the cis-side of the stacks and a network of overlying ER cisternae contained numerous membranous tubules and vesicles of two c lass sizes: 50-100 nm vesicles and microvesicles 5-10 nn in diameter, The tubules formed tight networks, known as cis-elements or cis-Golgi networks (CGN), which were strictly parallel and next to the first or cis-saccule of the stack. The cis-elements were continuous with more l oosely arranged peripheral tubules which formed elaborate, intertwined and interconnected networks. These peripheral tubules closely approxi mated the overlying ER cisternae in areas often showing fuzz-coated fi nger-like projections. Occasionally such peripheral tubules were conti nuous with ER cisternae. The saccules forming the stacks were continuo us with membranous tubules which not only connected saccules of adjace nt stacks, but also saccules of the same stack. These tubules were als o connected with the tight tubular networks forming the cis-elements a nd the broad networks formed by the peripheral membranous tubules. Ves icles (50-100 nm) and microvesicles (5-10 nm) frequently formed aggreg ates in the peripheral Golgi region next to areas of ER membrane free of fuzz-coated projections. The microvesicles, embedded in a denser cy toplasmic matrix, had a more or less distinct delimiting membrane sugg estive of their disintegration in this juxta-ER location. The 50-100 n m vesicles that were seen at the periphery of the vesicular aggregates appeared to form mainly from the membranous tubules of the Golgi cort ex. Conclusions: Thus the saccules and membranous tubules of the sperm atid's Gels cortex formed a single continuous membranous system connec ted to ER cisternae. The vesicles, seemingly arising from the membrano us tubules, appear to follow a retrograde pathway and undergo dissolut ion next to ER cisternae. (C) 1994 Wiley-Liss, Inc.