Sunao Kanda

Testicular development in Chinese Meishan boars

The developmental process of the testis and age-related changes in the morphology of rete testicular spermatozoa were investigated in Meishan boars at 1 to 364 days of age. Testicular weight and the diameter of seminiferous tubules increased rapidly until 150 to 180 days of age. Leptotene stage spermatocytes, round spermatids and spermatozoa were first found in the section of seminiferous tubules at 30 to 45, 60 and 75 days of age, respectively. However, after 105 to 120 days of age, most rete testicular spermatozoa were morphologically normal. These results indicate that Meishan boars reach puberty as early as 75 days of age, though the testes acquire the ability to produce morphologically normal spermatozoa at about 120 days.

Ovarian development in Meishan pigs.

Ovaries collected from a total of 35 Meishan gilts of various ages were morphologically and histologically examined. Vesicular follicles were first observed in ovarian sections at 45 d of age. Simultaneously, protruding follicles appeared on the surface of the ovaries, and then ovarian weight increased rapidly with an increasing number of protruding follicles. About half of the gilts between 75 and 90 d of age had ovaries with corpora lutea, indicating that some of them had started estrous cycles before reaching 75 d of age. In Meishan gilts treated with exogenous gonadotropins, ovaries were stimulated as early as 45 d of age. These results suggest that the precocity of Meishan gilts may include the development of vesicular follicles in the ovaries at an early age.

Influence of season on characteristics of epididymal and ejaculated semen in Meishan boars

Most of the epididymal spermatozoa collected in all the seasons examined maintained an ability to move progressively, had a cytoplasmic droplet in the distal site of the middle piece, and were morphologically normal. Reduced desire to mount a dummy was not observed during the experimental period. Characteristics of ejaculated semen were not significantly altered throughout the year. However, progressive motility and acrosomal integrity of spermatozoa ejaculated between July and September were more susceptible to storage at 4 degrees C than spermatozoa ejaculated during the other months and acrosomal integrity of spermatozoa ejaculated during the 3 months was to freezing-thawing. These results indicate that the reproductive activity of Meishan boars in Japan is only slightly influenced by season, but semen ejaculated during the summer is less suitable for storage than that ejaculated during the other seasons of the year.

Development of the Accessory Genital Glands in Meishan Boars

生後の雄梅山豚における精のう腺,前立腺体部および尿道球腺の発達過程を形態学的および組織学的に観察した.すべての副生殖腺の重量は30～45日齢以後に顕著に増加した.1日齢の精のう腺および前立線体部では,腺上皮は未発達で,腺腔の拡大も不十分であった.しかし,45～60日齢になると,腺の終末部に部分的な分枝が見られ,腺腔にはPAS陽性の分泌物が認められた.75～90日齢では,腺の終末部は十公に発達した組織像を示した.他方,尿道球腺については,1日齢で腺の終末部に分枝が見られ,腺腔内にはPAS陽性の分泌物が観察された.30～45日齢になると,終末部は急速に拡大するとともに,分枝を増し,腺腔はPAS陽性物質で満たされていた.以上の結果から,雄梅山豚の精のう線,前立腺体部および尿道球腺は,それぞれ75～90日齢,75～90日齢および30～45日齢には十分に発達した分泌機能を備えると考えられる.

Chemical composition of rete testicular fluid collected from conscious goats

カテーテル法によりヤギ生体より採取した精巣網液および同一ヤギ個体より採取した血漿の化学組成を調べ,両者を比較した。遠心分離により精子を除去した精巣網漿液の滲透圧は血漿と変わらなかったが,イオン組成は異なっており,また尿素窒素含量はほぼ同じであったが,脂質,グルコース,乳酸および蛋白質の含量は血漿にくらべ著しく低かった(表1)。精巣網漿液に含まれる主要なアミノ酸はグルタミン酸,グリシン,アスパラギン酸,アラニン,グルタミン,スレオニンおよびセリンで,このうち前三者は血漿中よりも高濃度に存在した。また,8種類の酵素の活性を調べた結果,ml当たりで血漿中よりも高い活性を示したのは,コリンエステラーゼと酸性ホスファターゼであった(表2)。以上の結果から,ヤギ精巣網液の化学組成はヒツジ,ウシ,ブタなどのそれと大差ないことが推定された。