坪林地區雄性赤腹松鼠之生殖生物學

Abstract

自1978年12月至1980年2月，每月自臺北縣坪林收購赤腹松鼠，共得雄松鼠146隻。雄松鼠由陰囊特徵及睾丸與副性腺組織切片觀察，可區分?幼松鼠30隻(20.5%)；發情前期松鼠16隻(11%)；生殖期松鼠82隻(56.2%)；退化期松鼠12隻(8.2%)；及復元期松鼠6隻(4.1%)。 睾丸成熟度指數(GSI)分佈曲線呈雙?型，兩?值分別?0.4及10.0，?距寬且中間型頻度極低(約15%)，顯示赤腹松鼠睾丸的發育與萎縮轉變迅速，睾丸指數8.0以上歸屬生殖型，0.6以上?幼鼠型，0.6至8.0?轉變形(包括發情前期、退化期及復元期松鼠)。自性成熟(包括生殖期、退化期及復元期)松鼠的睾丸成熟度指數週年頻度分佈顯示：1月至8月維持在8.0以上；3月居主顛?(10.7)；4、5月稍行下降；6-8月三月達另一次要巔?(分別?10.7、10.3、10.0)；9至11月急速下降至6.1；12月迅即回升。4至6月間性成熟雄性松鼠群中，部分個體其睾丸和副性腺組織學觀察，發現有萎縮(6.3%)及復元(10.4%)徵象；四種副性腺指數的月變化，與睾丸指數的變化相符。 由前述雄性生殖週期及未成熟松鼠出現頻度顯示，坪林地區赤腹松鼠可能有兩個亞族群，一年可能有兩次性成熟的轉換，初夏出生的松鼠，於夏、秋季發育至發情前期，冬末春初成熟，另一次夏季出生者，於隔年春天進入成熟前期，夏季成熟。

The reproductive biology of the red-bellied tree squirrel, Callosciurus erythraeus, was studied morphometrically and histologically. Conclusions were drawn based on 146 male squirrels of different reproductive states, collected at Pin-Lin, Taipei Hsien, from December, 1978 through February, 1980. According to the histological study of testes and accessory glands, five distinct classes of sexual development were recognized in the squirrel: 30 infants (20.5%), 16 prepubertal squirrels (11%), 82 functional adult males (56.2%), 12 degenerating adult males (8.2%), and 6 redeveloping adult males (4.1%). The gonado-somatic index (GSI), a ratio of the testes weight to the body weight was a reliable indicator for the reproductive state of the male. The infantile male had GSI below 0.6 and the sexually functional male above 8.0. The prepubertal, degenerating and redeveloping adult had GSI in between. Cyclic changes in the weights of the epididymis, seminal vesicle, prostate gland, and Cowper’s gland were comparable to that of the testes. The adult male was sexually quiescent from September through -November. The male red-bellied tree squirrel reached its sexual activity in the age of one year. The spring litter grow faster and larger than the Summer one.