黑斑蛙和中华大蟾蜍精子的超显微结构研究

过去,在精子的超显微结构方面的研究虽然已积累了很多资料,但在无尾的两栖类,蛙和蟾蜍方面的研究却不多。施履吉等（1981）结合他们的生化工作,曾用液面铺片法研究了这两种两栖类染色质在超显微结构方面的异同。发现黑斑蛙的精子染色质保留了体细胞染色质的核小体的结构,而在蟾蜍染色质中则无核小体结构,取而代之的则为由精蛋白和DNA组成的纤维状结构。然而在原位的情况下,黑斑蛙（Rana nigromacu-lata）和中华大蟾蜍（Bufo bufo asiaticus）的染色质呈何形态尚需做进一步的研究。

ULTRASTRUCTURAL STUDIES ON THE SPERMATOZOA OF THE FROG RAN A NIGROMACULATA AND THE TOAD BUFO BUFO ASIATICUS

Investigations on the ultrastructures of spermatozoa have been carried out by a number of authors, but the research works with respect to the anuran Amphibia, frog and toad, are scarcely found. Sze et al (1981) , using the surface-spreading technique in combination with the biochemical method, studied on the chromatin structure of the sperms of the frog Rana nigroma-culata and the toad Bufo bufo asiaticus and discovered that the former continues to have the nucleosomal structure, while the latter appears to have a fibrous structure, mainly composed of protamine and DNA, instead of showing the nuchosomal structure. The present works were intended to carry out the in situ studies on the chromatin structures of the two above-mentioned anurans. As a result of these studies, it was found that the sperm chromatin of R, nigromaculata, which is known to have the persistent nucleosomal structure, shows a granular form with the diameter of the granules around 100 A and the granules distributed densely and evenly inside the nucleus, while that of B. bufo asiaticus, which is reported to have a fibrous structure, revealed a filament-or rod-like appearance, with the filaments or rods scattered loosely and irregularly with in the nucleus. According to Balinsky (1975) and a preliminary study of our laboratory (Sze et al, unpublished) , we know that during the fertilization process of higher animals, centrosome has as an origin from sperm midpiece, hence we carried out an observation on the status of centrioles in the Rana and Bufo sperms. It was revealed that both sperms possess two centrioles in the mid-piece, with one proximal and the other distal to the nucleus as usually found, and that these two centrioles are perpendicular to each other. So far as we can discern, the most obvious difference between these two species is on the fact that the proximal centriole of Bufo is located within the invaginated portionof the nucleus, while that of Bana is situated near to, but outside the nuclear indentation. The acrosomes and tails of these two species were also carefully examined. The acrosomc of the former is atypical and appears to be composed of vesicles and granules, but that of the latter is shown to be quite complex and made up of outer acrosomal membrane, subacrosomal space, acrosomal contents and equatorial segment. As to the tail region, these two species arc also different by the fact that Bufo has an undulating membrane, but Rana has no such structure ever been observed. Besides, the ultrastruclurcs of these two anuran species are discussed in connection with their respective functions.