ハコネサンセウウヲに見出された精巣卵 : (附)精巣卵の性質に關する一考察

スポンサーリンク

概要

論文の詳細を見る
The occurrence of the testis-ovum among anurans has been described by many authors, and it seems to be rater common in the natural condition; while, on the contrary, in urodelans there are on record only a few instances of this anomaly of the genital organs. The cases of LA VALETTE ST.GEORGE (′95) in Triton, and of WILDER & PEABODY (′24) in Eurycea, are to be accepted as hermaphrodite. An instance described by KRIZENECKY (′17) in adult Triton cristatus showed the presence of ova within the normal testicular lobules. The three cases of the testis-ovum in the lungless salamander, Onychodactylus japonicus (HOUTTUYN) to be described here are cases which have been found while the writer was studying the germ cells of urodelans. Among them. one individual (Sp. NO.932) is an interesting gynandromorph, the right side of whose body was male-like and the gonad a normal testis; the lift female-like, and the gonad containing ova within the lobules of an otherwise normal testis. The full description of the case of a gynandromorph will shortly appear in another paper. The first specimen was caught at Mt.Ishizuchi on May 24-25, 1934, to be used in the study of the chromosomes; therefore it lacks the detailed morphological and anatomical observations. Both testes, however, had an abnormal shape, with the gonad on each side containing many ova which were visible to the naked eye. In sections these ova are about forty in number. The microscopical observations of the testicular tissues with the ova similar to that found in the second specimen will be described below. The second specimen (Sp. No.912) was caught at the same place on May 11, 1936. This individual was 152mm in total length and had the external characteristics of a male, but its hind limbs especially corneous metatarsal tubercles were not developed as much as those of a genuine male collected at the same time, and the tail showed the shape of a female. The genital organs were in a well-developed condition typical of males, with a pair of vas deferens and paired testes, but the shape of the testes was not typically male, and this abnormal shape was caused by the presence of ova. Sections through the testes showed 19 large ova in the left testis and 12 in the right one. These ova are the same in number as those found in the normal mature ovary. The size of the ovum within the testicular lobule was 0.5-0.9mm in diameter and the largest one measured about 1mm. Many of the tubules were typically male, with masses of ripe spermatozoa. In general an ovum was found in a tubule, and occupied almost the entire space of it. But frequently two or three ova were found in a tubule, and a tubule containing an ovum was always very much larger than the normal one. The ova have a quantity of yolk and the cytosome is well differentiated. There is visible evidence of chromation-reticulum or numerous granules, which stained by HEIDENHAIN'S haematoxylin, in the nucleus. From these structures and the above-mentioned fact, it may reasonably be assumed that the testis-ova in this lungless salamander are true female germ cells, although they were smaller than those in a normal mature ovary at the breeding season. Recently, MAKINO (′34, ′35), in his description of some cases of testis-ova found in Carassius carassius and Diplacodes trivialis, states that the so-called ova in the testicular tissue probably have been derived from the hypertrophy of the spermatogonia. And according to his opinion, the testis-ova are mere oocyte-like ells, and he thinks they possess no functional value. Furthermore, he claims that this explanation will be applicable to every case of amphibians such as Rana and Bufo. In my specimens, however, I cannot admit that the explanation of MAKINO is applicable. The structure of the testis-ova is like that found in the normal ovary, and it shows distinctly that they have formed masses of yolk substance. The occurrence of ovarian cells in the testis described in this paper may demons
社団法人日本動物学会の論文
1936-10-15

著者

佐藤井岐雄
廣島文理科大學動物學教室

関連論文

スポンサーリンク