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1.
试验通过对鸭胚注射芳香化酶抑制剂(AI)和β-雌二醇(E2)构建性反转模型,观察其性腺外观形态变化,并荧光定量检测雌性基因P450arom、FOXL2、SF-1和雄性基因DMRT1、SOX9、AMH等6个基因在性反转和正常鸭胚中的表达情况。结果显示:芳香化酶抑制剂能促进公鸭性腺发育,母鸭表现雄化;雌二醇能促进母鸭性腺分化,公鸭表现雌化。DMRT1、SOX9、AMH表达趋势相似,AI促进基因表达使胚胎雄化;E2抑制基因表达使胚胎雌化。P450arom、FOXL2、SF-1在AI组中被抑制使胚胎雄化,在E2组中得到促进发生雌化。该研究结果为研究鸭胚性反转机制奠定理论基础。 相似文献
2.
芳香化酶抑制剂Fadrozole能诱导雌性鸡胚雄性化,而不影响出生时雄性鸡胚的性别,但Fadrozole是否影响公鸡出雏后的生长发育和繁殖能力尚不清楚。在性别分化前(E3.0),向农大3号矮小商品代鸡胚注入PBS和不同剂量的Fadrozole(0.、10.3、0.5、1.0mg和1.3mg分别为1F、F2、F3、F4和F5),以出雏后的公鸡作为试验材料,探索Fadrozole对出雏后公鸡的生长发育、精清中的性激素和生长轴激素的影响。结果表明:高剂量组F4和F5分别为33.33%和13.33%,出雏率显著低于对照组P(<0.05),而低剂量组F1、F2和F3与对照组相比,出雏率无显著变化(P>0.05);各剂量Fadrozole处理组和对照组的体重和胫长在8周龄和20周龄时无显著差异P(>0.05);性成熟后(30周龄),F5精清中的睾酮(T)和雌二醇(E2)显著高于对照组和其他各处理组(P<0.05),但ln(T/E2)在各处理组和对照组差异均不显著(P>0.05);本试验说明Fadrozole不影响雄性胚胎的性腺分化,但高浓度的Fadrozole不利于鸡胚的发育;Fadrozole不影响出生后公鸡的生长发育、精清中的生长轴激素激分泌和精清中睾酮与雌二醇的比值。 相似文献
3.
雌激素受体在鸡上的研究进展 总被引：1，自引：0，他引：1
雌激素在雌性性分化和繁殖的调节中起着十分关键的作用[1].雌激素首先在脊椎动物的胚胎时期的卵巢中产生.哺乳动物性腺的分化独立于雌激素的产生,试验表明雌激素在其他的脊椎动物的性腺分化中起着关键的作用[2,3].雌激素在鸟类卵巢的分化中起到决定性的作用,胚胎时期的鸡胚胎性腺能够合成类固醇类激素,包括雌二醇,并且雌性性腺比雄性分泌更多的类固醇类激素,外源性雌激素可以使雄性雌性化,而雌激素的对抗物则可以扰乱正常的卵巢的形成,如果给遗传上的雌性注射芳香化酶抑制剂就可以使其雄性化,同时外源性雌激素也可使爬行动物睾丸雌性化.和其他的激素一样,雌激素是以配体介导转录因子方式通过特殊的核受体蛋白发挥其生物作用的. 相似文献
4.
鸡早期胚胎精原细胞和睾丸发生发育关系的研究 总被引：6，自引：2，他引：6
采用连续切片技术，研究了15～45期(孵化50h～19d)鸡早期胚胎发育过程中精原细胞与睾丸发生发育的关系。结果显示：孵化第22～28期(第3．5～5天)，原始生殖腺内的原始生殖细胞(PGCs)胞质内的糖原颗粒开始分解；第29期(孵化第6天)，鸡胚性腺开始分化，PGCs的糖原颗粒进一步分解；第31期(孵化第7天)，PGCs内的糖原颗粒完全消失。在雄性，性腺开始显示睾丸特征，PGCs分化为精原细胞；第34期(孵化第8天)，睾丸内曲精细管索开始形成，呈实心状，精原细胞位于其中；第35～37期(孵化第9～11天)，曲精细管索数量逐渐增加，索内精原细胞体积较大，呈圆形单层排列，且已分化出支持细胞，但数量不多，形态不易分辨，间质内有少量间质细胞；第38～40期(孵化第12～14天)，可见到典型的曲精细管，精原细胞数量增加，支持细胞亦增多；曲精细管间的间质细胞成群分布。第40～45期(孵化第16～19天)，两侧睾丸大小略有差异，右侧稍大于左侧，精原细胞数量明显增多，呈葡萄串状分布在曲精细管的中央；曲精细管的管腔已经形成，精原细胞已分层排列。 相似文献
5.
不同能量、蛋白水平日粮对育雏期塞北乌骨鸡生长发育规律、生化指标和肠道消化酶的影响 总被引：1，自引：0，他引：1
900只1日龄塞北乌骨鸡采用5(能量)×2(蛋白)两因素配方设计,试验期6周.结果:6周龄母鸡日粮代谢能(ME)为12.65 MJ/kg,体增重最高;公鸡日粮ME为12.00 MJ/kg,体增重最高.不同能量、蛋白水平日粮对21和42日龄塞北乌骨鸡血液生化指标存在不同程度的影响,高能量日粮可显著提高血清中血糖、总胆固醇和甘油三酯的含量(P＜0.05).在ME为12.65MJ/kg、蛋白为20％的日粮,3周龄母鸡的净体质量和肝质量极显著大于公鸡(P＜0.01),消化道质量公鸡极显著大于母鸡(P＜0.01).在ME为12.65 MJ/kg、蛋白为18％的日粮母鸡的净体质量板显著小于公鸡(P＜0.01);心质量显著小于公鸡(P＜0.05);消化道质量公鸡极显著大于母鸡(P＜0.01).0～6周龄消化道发育公鸡显著快于母鸡,但消化道总长变化不明显(P＞0.05).消化道总长与消化道各段长度的回归方程的决定系数(R2)均超过了0.807,总体效果公鸡略优于母鸡.21日龄时随着日粮能量水平的提高肠道胰蛋白酶活性除ME为10.85 MJ/kg与12.00MJ/kg组差异显著外(P＜0.05),公鸡其他各组间差异均不显著;母鸡在ME为12.65MJ/kg时最高.淀粉酶扣胰脂肪酶不同能量间差异均不显著(P＞0.05).42日龄公鸡脂肪酶活性和胰蛋白酶活性都不显著(P＞0.05);母鸡从总体来看,肠道消化酶活性随着日粮能量水平的提高而增加,日粮ME为12.65 MJ/kg达到最高. 相似文献
6.
为了研究雌激素对鸡胚性腺发育的影响,本试验通过测定雌二醇(E_2)对鸡胚的半数致死量,跟踪研究了不同剂量E_2对鸡胚性腺发育及母鸡产蛋情况的影响.结果表明,用32.5、42.3 μg/egg E_2处理孵化2.5 d鸡胚,继续孵化,出壳1周龄时雏鸡性腺外形呈现3种类型:第1种是左右性腺大小相当;第2种是左性腺比右性腺大,右性腺长度(1.5～2 mm)明显小于左性腺(5～6 mm);第3种是右性腺完全退化,但所有雏鸡的左性腺呈现典型的雌性特征.当E_2剂量为55.0、71.5、92.95 μg/egg时,其性腺外形呈现2种类型:一种是左性腺比右性腺大,另一种是右性腺完全退化,所有雏鸡的左性腺呈现典型的雌性特征.本试验结果还表明,E_2(剂量>32.5 μg/egg)处理后的鸡胚性成熟后,母鸡产蛋量下降,与对照组相比,蛋的受精率明显降低(P<0.01);公鸡的产精能力明显下降. 相似文献
7.
试验旨在研究FOXL2基因对鸡胚性腺分化的影响。本试验分为试验1组、试验2组和空白对照组（鸡胚数量分别为260、100、20枚），试验组通过胚盘下腔注射的方法分别将pLV-FOXL2慢病毒重组质粒、pLV空质粒注入胚胎期第2天的鸡胚，空白对照组不做处理并与试验组一起孵化至出雏，利用CHD1基因遗传性别鉴定的方法对出雏的雏鸡进行性别检测，分析其性腺解剖学、组织学结构变化，并利用免疫组化的方法检测性腺FOXL2和CYP19A1蛋白表达量。结果显示，试验1组遗传性别为公的23只，遗传性别为母的18只，表型性别为公的21只，表型性别为母的18只，其中有2只表型性别不典型，左侧性腺发生变化，朝卵巢结构转变；试验2组遗传性别为公的9只，遗传性别为母的12只，表型性别与遗传性别一致。阳性PCR检测结果显示，试验1组获得阳性个体10个，阳性率为24.4%（10/41）；试验2组获得阳性个体8个，阳性率为38.1%（8/21）。性腺解剖学结果显示，阳性pLV-FOXL2雄性鸡胚左侧性腺体积明显大于右侧性腺，表现膨松状态；组织切片结果显示，雄性鸡胚性腺具有典型的卵巢皮质层和髓质层结构；阳性pLV-FOXL2雌性鸡胚性腺的发育无明显变化。免疫组化结果显示，FOXL2和CYP19A1蛋白在试验1组左右侧睾丸中的表达量与空白对照组母鸡卵巢中的表达量相似，显著高于试验2组（P<0.05）。以上结果表明，FOXL2基因可能促进鸡雄性性腺的性反转，在鸡性腺分化和发育过程中发挥着重要的作用。 相似文献
8.
大豆黄酮对肉仔鸡内分泌激素与免疫机能的影响 总被引：4，自引：0，他引：4
选用240只1日龄艾维菌肉鸡,分别随机分为四个组,对照组饲喂基础日粮,试验组在基础日粮中分别添加5 mg/kg、10 mg/kg、15 mg/kg大豆黄酮。研究结果表明:(1)日粮添加大豆黄酮对肉公鸡免疫器官重量有增加的趋势,但差异不显著(P>0.05),(2)添加大豆黄酮仅49日龄公鸡T淋巴细胞ANAE阳性率差异显著,而其余差异均不显著(P>0.05);(3)添加大豆黄酮对肉用母鸡血清尿素氮含量影响不大,而公鸡血清尿素氮水平均显著降低,(4)添加大豆黄酮对肉用公鸡血清GH、IGF-1、睾酮匀有显著影响,而对母鸡血清GH、IGF-1无显著影响。 相似文献
9.
本研究旨在考察持续高温对不同性别北京油鸡脂肪代谢及血液脂肪细胞因子水平的影响.选择健康、体重相近的49日龄北京油鸡公母各72只[公鸡平均体重(608.58±13.07)g;母鸡平均体重(518.50±8.33)g],随机分在2个处理中:高温组,(35.00±0.37)℃;适温组,(25.00±0.38)℃,每个处理设6个重复,每个重复6只鸡.试验持续23 d.测定试验第12、23天时的血液生化指标、血液脂肪细胞因子水平及脂肪组织脂蛋白酯酶活性.结果表明:1)对公鸡而言:持续高温12 d时血清胰岛素水平显著升高(P＜0.01),血浆甘油三酯含量显著降低(P＜0.01).持续高温23 d时血清胰岛素水平和血浆甘油三酯含量显著降低(P＜0.01),血浆葡萄糖含量显著升高(P＜0.01);对母鸡而言:持续高温12 d时血浆甘油三酯、游离脂肪酸含量显著降低(P＜0.05).持续高温23 d时血浆甘油三酯、游离脂肪酸含量无显著变化(P＞0.05),血浆极低密度脂蛋白含量有增加趋势(P =0.065),血浆葡萄糖含量显著升高(P＜0.01).2)持续高温12 d时公母鸡的肌间脂肪脂蛋白酯酶活性都显著降低(P＜0.05),持续高温23 d时公鸡的肌间脂肪脂蛋白酯酶活性显著降低(P＜0.05),而母鸡的无显著变化(P＞0.05).3)公母鸡血浆脂联素、抵抗素水平在高温下都无显著变化(P＞0.05);持续高温12 d时公鸡血浆瘦素水平显著降低(P＜0.01),母鸡的显著升高(P＜0.05).由此可知,随着持续高温时间的延长,母鸡血浆游离脂肪酸、甘油三酯含量及肌间脂肪组织脂蛋白酯酶活性受高温影响下降程度减小,公鸡血浆甘油三酯含量及脂肪组织脂蛋白酯酶活性下降程度加大. 相似文献
10.
多氯联苯对鸡胚性腺发育的毒性和雌性激素作用 总被引：4，自引：1，他引：3
研究了内分泌干扰物多氯联苯 (PCB)对鸡胚性分化开始后性腺发育和配子分化的影响。在孵化的第 10天向气室内注入 Aroclor12 5 4或雌激素 ,第 19天取出睾丸和卵巢 ,进行形态学观察。结果显示 ,PCB明显促进卵巢皮质的发育 (P<0 .0 5 ) ,效果类似 17β-雌二醇 (E2 ) ;对睾丸发育也呈现微弱的雌激素样作用 ,生精细胞分化受到抑制 ,细精管管壁显著变薄 (P<0 .0 1) ,而 E2 作用于睾丸会导致睾丸萎缩 ,甚至雌性化 ,睾丸横截面积比对照组显著减少 ,细精管管壁也变薄 (P<0 .0 5 )。PCB的上述雌激素样作用能被克罗米酚 (clom iphen)阻断。此外 ,与 E2 相比 ,PCB对雌性和雄性生殖细胞表现出强烈的毒性作用 ,使大多数生殖细胞发生核固缩和胞质空泡化 ,细胞间隙增大 ,雄性的细精管结构也受到破坏。以上结果表明 ,PCB对鸡胚性腺呈现出毒性和雌性激素的双重作用 相似文献
11.
Oluwaseun Serah Iyasere David Oluwatowo Adeuyi Rasheed Adebayo Alade Samuel Olutunde Durosaro Mathew Wheto Olajide James Ogunbanjo Lucky Ebhodage Oyakhilome Samuel Emmanuel James Olamitibo Daramola 《Reproduction in domestic animals》2020,55(5):567-573
To date, there is no reported standard mating ratio for Nigerian native chickens despite their large population in the country. This study investigated the effect of mating ratio on behaviour, semen quality and level of stress. Sixty-three (9 cocks and 54 hens) sexually matured birds were randomly assigned to three mating ratios (MR) of 1 cock to 3 hens (1C:3H), 1 cock to 6 hens (1C:6H) and 1 cock to 9 hens (1C:9H), and each MR was replicated three times. Each cock spent 2 weeks in a particular MR before it was moved to another. By the 6th week, all cocks had experienced the three mating ratios. Behaviour of the hens and sexual behaviour of the cocks were observed in the morning and evening, respectively, for 6 weeks. At the end of 2nd week in each MR, semen samples were collected and evaluated for motility, morphology, liveability and concentration, and blood samples were also taken from the cocks to determine the heterophil/lymphocyte (H:L) ratio, an indicator of stress. There was also no significant effect of mating ratio on the fertility of eggs and hatchability of the chicks. The number of hen–hen aggression instances, frequency of visits to the nest box and duration of nesting was not influenced by the mating ratio. However, the duration of nest seeking was higher at 1C:3H and lower at 1C:9H. A mating ratio of 1C:9H is therefore recommended for farmers interested in raising Nigerian native chickens. 相似文献
12.
High levels of estrogen produced by boar testes and the presence of estrogen receptors in both interstitial and tubular compartments are consistent with a direct role for estrogen in regulation of testicular cell function. This study investigated the importance of estrogen on hormone production by Leydig cells and seminiferous tubules in the developing boar. Thirty-six 1-week-old littermate pairs of boars were treated weekly with vehicle or 0.1 mg/kg BW Letrozole, an aromatase inhibitor, until castration at 2, 3, 4, 5, 6, 7, or 8 months. Tissue was collected and Leydig cells and seminiferous tubules were isolated. In a separate study, five untreated boars (ages 1.5-4 months) were castrated and Letrozole was added in vitro to Leydig cell and seminiferous tubule cultures. Leydig cells were cultured for 24h with and without porcine LH. Media were assayed for estradiol (E(2)) and testosterone (T) concentrations by RIA. Seminiferous tubules were cultured for 4h with and without porcine FSH; media were assayed for E(2) and immunoreactive inhibin (INH). In vivo aromatase inhibition decreased basal E(2) and increased basal T production by cultured Leydig cells. Basal seminiferous tubule production of E(2) but not INH was reduced. Decreasing estrogen synthesis in vivo did not alter LH-induced Leydig cell E(2) production or FSH-induced seminiferous tubule INH production. INH production decreased with advancing age regardless of treatment. In conclusion, in vivo aromatase inhibition altered baseline steroid production by cultured Leydig cells and seminiferous tubules but had little effect on response to gonadotropins. 相似文献
13.
针对贵妃鸡在国内外珍禽市场上不可估量的发展前景,为了选育出贵妃鸡自别雌雄配套系,本研究根据伴性遗传基因的遗传原理和羽速基因的遗传特点,采用现代家禽育种方法对贵妃鸡第二世代表型慢羽公鸡进行了测交试验。采用人工授精,所产种蛋分别孵化。其中用13只表型为慢羽公鸡,与52只快羽母鸡组成第1类测交试验,结果每只公鸡的后代中都有快羽雏出现,且快慢羽比例几乎为1:1(217:232);由20只表型慢羽公鸡与80只慢羽母鸡组成的第2类测交试验,结果每只公鸡的后代中,也都有快羽雏出现,而且快慢羽比例几乎接近1:3(197:520)。可见,所用的33只公鸡经测交证明全为杂合体,同时表明两个不同质量性状测交结果完全符合孟德尔遗传定律。 相似文献
14.
公鸡斗架是常见的一种动物争斗行为,作者通过对公鸡斗架行为的根源、方式和结局的分析,说明公鸡斗架行为是由基因控制的,是自然选择的结果,斗架的本质是繁殖斗争,目的是取得与更多异性交配的机会,留下更多的后代。公鸡斗架的节制性符合进化稳定性策略,在进化上具有重要意义。 相似文献
15.
公鸡斗架是常见的一种动物争斗行为,作者通过对公鸡斗架行为的根源、方式和结局的分析,说明公鸡斗架行为是由基因控制的,是自然选择的结果,斗架的本质是繁殖斗争,目的是取得与更多异性交配的机会,留下更多的后代.公鸡斗架的节制性符合进化稳定性策略,在进化上具有重要意义. 相似文献
16.
采用全天观察法,对京海黄鸡公鸡的性行为进行记录,获得京海黄鸡公鸡性行为的过程,总结京海黄鸡公鸡性行为规律,分析京海黄鸡公鸡个体间性行为的差异,并通过检测精液品质,研究京海黄鸡公鸡性行为与精液质量的关系;通过观察晴天与阴天时的性行为,分析不同的天气对京海黄鸡公鸡性行为的影响,结果显示：京海黄鸡性行为个体间差异不大,受天气的影响较为明显。本文通过对京海黄鸡公鸡性行为的观察研究,为进一步提高京海黄鸡公鸡自然交配的授精率和繁殖性能提供一定的科学依据。 相似文献
17.
Detection of chicken anemia virus in the gonads and in the progeny of broiler breeder hens with high neutralizing antibody titers 总被引：2，自引：0，他引：2
Previous evidence for the presence of chicken anemia virus (CAV) in the gonads of immune specific-pathogen-free chickens raised the question whether this occurs also in commercial breeders. The presence of CAV was investigated by nested PCR in the gonads and spleens of hens from two 55- and 59-week-old, CAV-vaccinated (flocks 2 and 3), and two 48- and 31-week-old non-vaccinated broiler breeder flocks (flocks 1 and 4). In addition, lymphoid tissues of 20-day-old embryos from these hens were also investigated for the presence of CAV. CAV was detected in the gonads and of 5/6 and 11/22 of the vaccinated hens and in some hens also in the spleen alone. Embryos from 7/8 and 5/18 of these hens were positive. In the non-vaccinated flocks, CAV was detected in the gonads of 11/34 and 10/10 hens in flocks 1 and 4, respectively. In addition, 11 birds in flock 1 had positive spleens. CAV DNA was detected in 3/11 and 2/10 of their embryos. CAV-positive gonads and embryos were detected in samples from hens with moderate as well as high VN antibody titers. Vaccinated chickens positive for CAV in the gonads and in their embryos had VN titers ranging from >1:512 to <1:2048. In non-vaccinated chickens, the VN titers of CAV positive chickens ranged from 1:128 to 1:4096. These results demonstrate that CAV genome can remain present in the gonads of hens in commercial broiler breeder flocks even in the presence of high neutralizing antibody titers that have been associated with protection against CAV vertical transmission. It also suggests that transmission to the progeny may occur irrespectively of the level of the humoral immune response in the hens. 相似文献
18.
Sechman A Rzasa J Paczoska-Eliasiewicz H 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2003,50(7):333-338
HyLine Brown laying hens at 30 weeks of age were treated twice daily with Fadrozole, a non-steroidal aromatase inhibitor (AI; 1 mg/kg body weight; i.m.) for six consecutive days; control hens received saline. Blood was collected every day 0.5 h after oviposition, i.e. just before AI treatment. Ovarian steroids: progesterone (P4), testosterone (T) and estradiol (E2), and iodothyronines: thyroxine (T4), triiodothyronine (T3) and reverse-triiodothyronine (rT3) were measured in blood plasma by radioimmunoassay methods. In AI-treated hens a gradual delay in oviposition time was observed. AI significantly decreased P4 and E2 levels, maximally by 43% on day 4 and by 74% on day 5, respectively, and elevated T level, maximally by 248% on day 4. Simultaneously, the increases in T4 and T3 levels with no changes in rT3 levels were observed. The maximal effect of AI on T4 and T3 levels was found on day 4 (60% increase) and day 5 (312% increase), respectively. Moreover, statistically significant, negative coefficient of correlation between E2 and T3 (r = -0.51), and positive coefficient of correlation between T and T3 (r = 0.42) in AI-treated hens were found. The results obtained indicate that in mature laying hens there is a strong relationship between ovarian steroids and thyroid hormones, and suppression of E2 synthesis not only disrupts ovarian function but also affects the activity of the thyroid gland and peripheral metabolism of thyroid hormones. 相似文献
19.
Yukinori YOSHIMURA 《Animal Science Journal》2004,75(3):183-191
The current paper describes aspects of local immunity in the ovary and oviduct, and the significance of immunity to reproductive functions in hens. The immunocompetent cell populations in the ovary and oviduct change with a positive correlation to sexual activity, and gonadal steroid is one of the key factors in the increase. Local immune responses mediated by major histocompatibility complex class II and T cell subsets occur in response to infection by Salmonella enteritidis, which may contaminate eggs. In the ovary, immunocompetent cells are also suggested to play roles in the regulation of ovarian functions. Macrophages and T cells are likely to enhance the regression of atretic follicles to maintain the ovarian tissue microenvironment. Autoantibodies to ovarian tissues appeared in the hens with low egg laying frequency, suggesting that the auto‐antibodies may be one of the factors in the decline of egg production. In the oviduct, local immunity possibly has a role in the selection of sperm, though the immunoreactions may also affect sperm survival leading to the decline in fertility. The concentration of yolk IgY, which plays a role in maternal immunity transmission, significantly decreases with the aging of birds, whereas it is significantly increased by estrogen. Therefore, the immune system plays significant roles not only in defense against infection, but also in the functions of reproductive organs. Investigations on the local immune system in the reproductive organs and factors affecting it are of importance for the production of sterile eggs and improvement of reproductive functions. 相似文献
20.
Watanabe H Mogoe T Asada M Hayashi K Fujise Y Ishikawa H Ohsumi S Miyamoto A Fukui Y 《The Journal of reproduction and development》2004,50(4):419-427
The present study was conducted to obtain new information on relationships among serum testosterone (T), estradiol-17 beta (E(2)), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) concentrations and histology of seminiferous tubules in captured common minke and Bryde's whales during the feeding season. Blood samples and testes were collected from common minke (n=39 for blood samples, n=15 for testes) and Bryde's (n=14 for blood samples, n=7 for testes) whales captured from May 2001 to August 2001 in the Western North Pacific. Serum T concentrations, in 35.9% of the common minke and 57.1% of Bryde's whales, were below the detection limit (< 2.5 pg/ml). There were no significant differences in the serum concentrations of E(2), FSH, and LH among immature, mature common minke and Bryde's whales except that LH levels of immature Bryde's whales was higher than those of common minke whales. In most seminiferous tubules of mature whales, only a single-layer of spermatogonia was observed. However, spermatozoa were observed in seminiferous tubules in 2/13 of mature common minke and 4/4 of mature Bryde's whales with the low or undetectable T levels. These results indicate that the low serum T concentrations reflect the inactivity of spermatogenesis in both baleen whales, and that it is not possible to assess gonadal activity in either common minke or Bryde's whales using serum sex hormone concentrations during the feeding season. 相似文献