Acrosome Biogenesis in the Hamster: RESULTS(1)
Isolation of Acrosomal Fraction
The acrosomal matrix of intact spermatozoa exhibited subtle regional variations in electron density; the matrix positioned over the dorsal surface of the sperm head appeared less electron-dense than the matrix located ventrally within the acrosome (Fig. 1A). Specific structural elements of the acrosomal cap are released as an integrated complex after extraction of spermatozoa with Triton X-100 .
This assembly, termed the ALM complex, comprised three acrosomal structures (Fig. IB): the first a less electron-dense matrix domain (ml) derived from the dorsal surface of the acrosome, the second a more electron-dense matrix domain (m2) located ventrally in the intact acrosome; and the third the acrosomal lamina, which appeared to include the detergent-insoluble membrane-skeleton of the outer acrosomal membrane and remained adherent to the dorsal surface of the ml matrix domain. Fractionation of Triton X-100-extracted spermatozoa on Percoll density gradients yielded a highly purified ALM fraction; each complex retained the ml and m2 matrix and the acrosomal lamina (Fig. 1C). buy ampicillin
FIG. 1. A) Electron micrograph showing cross section through the head region of a cauda epididymal spermatozoon. The acrosomal cap overlies the dorsal surface of the nucleus (n). Note that the acrosomal contents located dorsal ly appears less electron-dense than the acrosomal contents located ventrally (*). B) Electron micrograph of cross section of Triton X-100-extracted sperm head showing an acrosomal lamina-matrix complex separating from the underlying nucleus (n). Each complex consists of two contiguous acrosomal matrix domains of differing electron density (ml and m2) and detergent-insoluble elements of the outer acrosomal membrane, termed the acrosomal lamina (al), which remains adherent to the ml matrix. C) Electron micrograph of purified ALM fraction; note the absence of other contaminating sperm structures. A and B, X48 ООО; С, X18 000 (reproduced at 69%). al, Acrosomal lamina; oa, outer acrosomal membrane; ia, inner acrosomal membrane; es, equatorial segment; pm, plasma membrane; ps, postacrosomal segment.