[Problem of terminology in characteristics of spermatozoa of metazoa]

Difficulties in characterization of spermatozoa of the Metazoa are now related to insufficiency of the traditional terms "primitive spermatozoon", "modified spermatozoon", and "aberrant spermatozoon" introduced by G. Retzius and A. Franzen for description of intermediate forms discovered in the 20th century. In this respect, some authors propose to reject the Retzius' and Franzen's terms and turn to the terminological system of D. Rouse and B. Jamieson, the terms of which ("ectaquaspermatosoa", "entaquaspermatozoa", and "introspermatozoa") determine specific features of insemination, but do not reflect the structure of spermatozoa. The assertion of "helplessness" of the traditional structural Retzius' and Franzen's terms is unfounded. Their preservation is desirable if one wishes to preserve the comparative-morphological approach to the characterization of male gametes of the Metazoa. The terms "primitive spermatozoon", "modified spermatozoon", and "aberrant spermatozoon" will become more universal if the method of their combined utilization is applied.