• 19
  • Acrosome Biogenesis in the Hamster: RESULTS(1)

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
Fig1Acrosome biogenesis
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.

Online Pharmacy