畜牧兽医学报  2021, Vol. 52 Issue (4): 1103-1114. DOI: 10.11843/j.issn.0366-6964.2021.04.026    PDF    
犬正常发情期与患子宫蓄脓的子宫和卵巢组织结构及乳铁蛋白表达的对比
刘雨珂, 徐倩倩, 孙佩芳, 陈美伊, 刘铭峰, 段德勇     
湖南农业大学动物医学院, 长沙 410128
摘要:本研究旨在探明犬子宫和卵巢在正常发情期与患子宫蓄脓时,其组织结构及乳铁蛋白(lactoferrin,LF)表达的变化特征。应用Masson’s、VVG、PAS组织化学染色方法观察乏情期、发情期、患子宫蓄脓时犬子宫及卵巢的组织结构特点,用免疫组织化学SP法观察LF的分布特征。结果显示,正常发情期犬:乏情期、发情期子宫内膜肌层厚度比分别为0.762 0、0.924 3;乏情期子宫固有层中胶原纤维含量大于发情期,发情期卵巢中胶原纤维含量大于乏情期;子宫血管层及卵巢血管内弹性膜清晰完整;子宫腺在乏情期时浅层管腔小,深层较大、腺管上皮为单层柱状上皮、上皮细胞及管腔内PAS阳性反应较强,发情期子宫腺管腔变大、腺管上皮为单层立方上皮、上皮细胞及管腔内有PAS阳性反应;子宫黏膜上皮在乏情期和发情期均为单层柱状上皮,但胞核位置不同,乏情期胞核位于中央,发情期胞核位于顶部。患子宫蓄脓犬:子宫内膜肌层厚度比为1.615 0;子宫固有层和卵巢中胶原纤维含量少于正常发情期;子宫腺管腔大,且形状不规则,管腔内有炎性细胞浸润,腺管上皮为单层立方上皮,有淋巴细胞位于基膜,上皮细胞及管腔内PAS阳性反应较弱;子宫血管层及卵巢血管内弹性膜较正常发情期变薄,且有断裂现象;子宫黏膜上皮为单层柱状上皮,胞核位于基底。LF在乏情期子宫腺上皮和卵巢中的表达水平高于发情期,而在子宫黏膜上皮中发情期的表达水平高于乏情期。患子宫蓄脓时犬子宫和卵巢中LF的表达水平均较低。综上表明,犬正常发情期与患子宫蓄脓时的子宫和卵巢组织结构特点显著不同,LF的表达水平也存在差异。
关键词正常发情期    子宫蓄脓    犬子宫和卵巢    组织结构    乳铁蛋白表达    
Comparison of Histological Structure and Lactoferrin Expression in Uterine and Ovarian of Dogs during Normal Estrus and with Pyometra
LIU Yuke, XU Qianqian, SUN Peifang, CHEN Meiyi, LIU Mingfeng, DUAN Deyong     
College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China
Abstract: The purpose of this study was to investigate the changes in histological structure and the expression of lactoferrin (LF) in the uterus and ovaries of dogs during the normal estrus and with pyometra. Masson's, VVG and PAS histochemical staining were used to observe the histological characteristics of uteruses and ovaries in anestrus, estrus, and pyometra. The immunohistochemical SP method was used to observe the distribution of LF. The results showed that the endometrium/myometrium ratios in the period of anestrus and estrus were 0.762 0 and 0.924 3, respectively. The content of collagen fibers in the uterine lamina propria in anestrus was higher than that in estrus, and the collagen fibers content of ovary in estrus was higher than that in anestrus. The internal elastic membranes of uterine vascular layer and ovarian blood vessels were clear and intact in anestrus and estrus. During the period of anestrus, the superficial lumen was small and the deep lumen was large, the epithelium of glandular duct was consisted of the single layered columnar epitheliums, and the PAS positive reaction was strong in epithelial cells and glandular cavity. During the period of estrus, the glandular lumen became larger, the glandular epithelium was the single layered cuboidal epithelium, and PAS positive reaction was found in the epithelial cells and glandular lumen. The endometrial epithelium was monolayer columnar epithelium in both estrus and anestrus periods, but the position of the nucleus was different. The endometrial epithelium nucleus of anestrus period was located in the center of cell, the endometrial epithelium nucleus of estrus period was at the top of cell. When the dogs have pyometra, the endometrium/myometrium ratio was 1.615 0, the content of collagen fibers in the lamina propria of uteruses and ovaries was less than that during normal estrus, the glandular lumen was large and irregular in shape, the inflammatory cells infiltrated in the lumen, the glandular epithelium was the single layered cuboidal epithelium, the lymphocytes were located in the basement membrane, and PAS positive reaction was weak in epithelial cells and lumen; the elastic membrane in uterine vascular layer and ovarian blood vessels became thinner and fractured compared during normal estrus; the endometrial epithelium was the single monolayer columnar epithelium, and the nucleus was located at basal plasma membrane. The expression level of LF in uterine glandular epithelium and ovaries in anestrus stage was higher than that in estrus period, and the expression level of LF in endometrial epithelium in estrus was higher than that in anestrus. The expression of LF in uteruses and ovaries of dogs with pyometra was lower. The results suggested that the histological characteristics of uteruses and ovaries of dogs in normal estrus and pyometra were significantly different, and the expression level of LF was also different.
Key words: normal estrous stages    pyometra    dog uterus and ovary    histological structure    lactoferrin    

子宫和卵巢作为雌性生殖系统中重要的器官,其结构会随生理阶段的改变及激素的作用而发生变化。由于在发情期犬卵巢大量分泌雌激素和孕激素,使得子宫发生如子宫内膜和肌层增厚、子宫腺管平均直径增加等变化[1-3],这些变化易诱发犬子宫内膜发生囊性增生(CEH),加之子宫颈的开张,易使细菌侵入子宫,引起子宫内膜感染,导致犬子宫蓄脓的发生[4]。虽已有诸多学者针对犬发情周期卵巢与子宫组织学结构[5],诱导发情后犬生殖器官组织学及组织化学特征[6],子宫蓄脓犬子宫和卵巢显微及超微结构[7],比格犬间情期与发情期卵巢与子宫组织形态学观察[8],犬子宫蓄脓的组织病理学观察和微生物分析[9],犬子宫雌激素受体的免疫组化检测及其与性激素水平的关系[10]等进行了研究,但上述研究均没有对比观察正常发情期与患子宫蓄脓时犬子宫和卵巢的组织结构变化。

乳铁蛋白(lactoferrin,LF)作为非特异性免疫的重要组成部分,不仅存在于乳腺的分泌物中,还广泛存在于生物体其他的体液和分泌物中,已证实其可在局部与Fe3+相结合而抑制细菌生长、参与局部免疫[11]。国内对LF的功能研究表明,一定剂量的LF可在小鼠肠道内有明显的抑菌作用[12];通过慢性鼻窦炎钩突黏膜中LF表达的研究,证实LF还存在于生物体其他分泌物中,并可参与构建局部免疫防御系统[13]。Esteban等[14]发现LF具有调节巨噬细胞活性和刺激淋巴细胞合成的能力;Kolm等[15]发现LF在马子宫内膜的表达量会随发情周期的变化而改变。但是目前尚未有研究表明LF在正常发情期和患子宫蓄脓时犬的子宫和卵巢中有表达,并参与局部免疫。鉴于此,本研究对发情期、乏情期犬的子宫与卵巢、患子宫蓄脓犬的子宫与卵巢,运用组织化学及免疫组织化学方法,对比分析组织结构的变化及乳铁蛋白的表达情况,拟为犬生殖生理的研究及子宫蓄脓疾病的预防及治疗提供形态学依据。

1 材料与方法 1.1 材料

1.1.1 实验动物   所有样品均由湖南农业大学动物医院经绝育手术采集,其中选取2~3岁健康犬发情期5例、乏情期5例,6~10岁患子宫蓄脓疾病犬5例。

1.1.2 主要试剂   兔多克隆乳铁蛋白(Lactoferrin,LF)抗体(11096-RP02)购自北京义翘神州生物技术有限公司;免疫组化SP染色试剂盒(SP-9001)购自北京中杉金桥生物技术有限公司;DAB显色试剂购自生工生物工程(上海)股份有限公司。

1.2 方法

1.2.1 组织化学染色法   组织经4%多聚甲醛固定后,梯度酒精逐级脱水,二甲苯透明,常规石蜡包埋,切片厚5 μm。切片经脱水、脱蜡后分别进行Masson’s、VVG、PAS染色,脱水、透明、封片。显微镜下观察并拍照。Masson’s三色(苯胺蓝)染色,胶原纤维呈蓝色,细胞质和肌纤维呈红色,核呈灰黑色;VVG染色弹力纤维呈黑色或蓝黑色,细胞质和肌纤维呈黄色,胶原纤维呈红色,核呈灰黑色;PAS染色显示糖原及其他PAS反应阳性物质均呈阳性,细胞核呈蓝色。

1.2.2 免疫组织化学SP法检测LF的分布   1) 5 μm石蜡切片常规脱蜡至水;2)在pH6.0且0.01 mol·L-1柠檬酸缓冲液中进行微波抗原修复,高火煮沸5 min后,中火维持8 min,室温下自然冷却;3)pH7.4且0. 01 mol·L-1的PBS内洗涤3次,每次3 min;4)滴加3%过氧化氢溶液,37 ℃下孵育10 min;5)同步骤3;6)滴加封闭液(SP试剂盒中A液,即10%非免疫性动物血清),湿盒中37 ℃下孵育15 min;7)滴加一抗(1∶1 000比例稀释的兔多克隆LF抗体),湿盒中37 ℃孵育2 h,同时添加1组阴性对照(用0.01 mol·L-1 PBS代替一抗);8)同步骤3;9)滴加生物素标记的二抗(SP试剂盒中B液),37 ℃下孵育15 min;10)同步骤3;11)滴加SP试剂盒中C液(即过氧化物酶标记的链霉亲和素),湿盒中37 ℃下孵育15 min;12)同步骤3;13)滴加新鲜配制的DAB显色3~10 min;14)自来水冲洗,苏木精复染、脱水、透明、封片。显微镜下观察并拍照。

1.2.3 图像分析   光镜下观察免疫组织化学切片,随机选取5张,每组切片在400倍显微镜(Olympus)下进行拍照,每张切片采集5个视野,用Image-Pro Plus 6.0软件进行图像分析,测定阳性反应物的平均光密度,采用SPSS 21.0统计软件对数据进行单因素方差分析,结果用“x±s”表示,P < 0.05为差异显著,P < 0.01为差异极显著。

1.2.4 发情周期的确认及子宫蓄脓病的诊断   乏情期与发情期的划分以马文芝[16]对犬发情周期内临床生理行为特征的研究为依据,结合犬主描述,初步判定犬的发情阶段。绝育术采集样本后,制作石蜡切片,并通过与Andersen等[17]和Vermeirsch等[18]对犬卵巢和子宫组织形态学的研究结果进行比对,最终确定本文采集到的犬子宫和卵巢样本处于乏情期和发情期。患子宫蓄脓犬子宫和卵巢样本的采集是通过观察病犬精神沉郁、腹部肿大、阴道可见脓性分泌物等临床症状;血常规检查白细胞、中性粒细胞数增加;B超检查子宫腔中呈低回声暗区,初步确诊为子宫蓄脓。通过手术取出子宫后,发现子宫角膨大,呈暗红色(图 1),切开后见大量黏稠脓性内容物,符合子宫蓄脓病理特征。

图 1 患子宫蓄脓犬的子宫和卵巢 Fig. 1 Uterus and ovary of dog with pyometra
2 结果 2.1 正常发情期犬子宫和卵巢组织结构特点

2.1.1 子宫肌层结构特点   乏情期肌束排列紧密,肌束间胶原纤维较少,肌纤维胞核较大,呈椭圆形且位于周边,胞质红染(图 2 AB);发情期肌束间隙增大,内纵行肌层肌束间隙显著增大,且胶原纤维较多,肌纤维胞核较小,呈圆形位于中央,胞质淡粉色(图 2 DE)。在肌层间的血管层中,乏情期与发情期子宫血管内弹性膜清楚,呈明显的波浪状,外膜中含有丰富的弹性纤维(图 2 CF)。内膜肌层厚度比(内膜厚度/肌层厚度)在不同时期显著不同:乏情期和发情期分别为0.762 0、0.924 3。

A、B. 乏情期子宫肌层;C. 乏情期子宫血管层血管;D、E. 发情期子宫肌层;F. 发情期子宫血管层血管;S. 浆膜层;CML. 环肌层;L. 血管腔;E. 外膜;M. 中膜;A、D. HE染色;B、E. Masson染色;C、F. VVG染色 A, B. Myometrium in anestrus; C. Blood vessels of vascular layer of uterus in anestrus; D, E. Myometrium of uterus during estrus; F. Blood vessels of uterine vascular layer during estrus; S. Serosa; CML. Circular muscle layer; L. Lumen; E. Tunica externa; M. Tunica media; A, D. HE staining; B, E. Masson staining; C, F. VVG staining 图 2 发情期和乏情期犬子宫肌层结构 Fig. 2 Structure of dog myometrium in estrus and anestrus

2.1.2 子宫内膜结构特点   乏情期固有层子宫腺在200×镜头下每个视野中的平均数为5~7个;深层腺管数多,且管径小于浅层腺管;腺上皮细胞为单层高柱状上皮,胞核呈圆形位于细胞的基底;胶原纤维含量较多,血管四周有少量弹性纤维(图 3 A~C)。发情期固有层子宫腺每个视野平均数为18~23个;腺管管径大于乏情期;腺上皮细胞为立方上皮,胞核呈卵圆形或圆形,位于细胞中央;胶原纤维含量少于乏情期,血管周围无弹性纤维(图 3 E~G)。

A~D. 乏情期子宫固有层;E~H. 发情期子宫固有层;LP. 固有层;UG. 子宫腺;A、E. HE染色;B、F. Masson染色;C、G. VVG染色;D、H. PAS染色 A-D. Lamina propria of uterus in anestrus; E-H. Lamina propria of uterus during estrus; LP. Lamina propria; UG. Uterine gland; A, E. HE staining; B, F. Masson staining; C, G. VVG staining; D, H. PAS staining 图 3 发情期和乏情期犬子宫固有层结构 Fig. 3 Structure of dog lamina propria in estrus and anestrus

PAS染色显示,子宫腺上皮细胞靠近腺腔处,乏情期、发情期均有阳性反应,且乏情期阳性反应程度大于发情期(图 3 DH)。

乏情期子宫黏膜上皮为单层柱状上皮,胞核呈柱状或圆形位于细胞的中央,胞质染色深,有散在的淋巴细胞;PAS反应集中于黏膜上皮细胞胞质及管腔中阳性分泌颗粒(图 4AC)。发情期黏膜上隐窝较乏情期数量多,子宫黏膜上皮细胞内有聚集脂滴,形成泡沫状上皮细胞,胞核位于细胞顶部且染色深,胞质淡染;PAS反应集中于黏膜上皮细胞基底面和游离面(图 4BD)。

A、C. 乏情期子宫黏膜;B、D. 发情期子宫黏膜;EM. 子宫内膜;A、B. HE染色;C、D. PAS染色 A, C. Endometrium of anestrus; B, D. Endometrium of estrus; EM. Endometrium; A, B. HE staining; C, D. PAS staining 图 4 发情期和乏情期犬子宫黏膜结构 Fig. 4 Structure of dog uterine mucosa in estrus and anestrus

2.1.3 卵巢结构特点   乏情期卵巢皮质中原始卵泡数量较多,初级卵泡和次级卵泡较少,有腔卵泡数量少。发情期卵巢皮质中可见1~2个大黄体,并有成熟卵泡及少量的初级卵泡和次级卵泡(图 5AD)。卵巢中胶原纤维数量在不同时期显著不同,发情期较乏情期多。在PAS反应中,均可在卵泡透明带处发现阳性反应,且强度相同(图 5BE)。在髓质中,乏情期与发情期卵巢血管内弹性膜清晰,外膜中含有较多弹性纤维(图 5CF)。

A. 乏情期卵巢皮质;B. 乏情期卵巢卵泡;C. 乏情期卵巢血管;D. 发情期卵巢皮质;E. 发情期卵巢卵泡;F. 发情期卵巢血管;PrF. 原始卵泡;PO. 初级卵泡;CL. 黄体;L. 血管;A、D. Masson染色;B、E. PAS染色;C、F. VVG染色 A. Ovarian cortex in anestrus; B. Ovarian follicle in anestrus; C. Ovarian blood vessel in anestrus; D. Ovarian cortex in estrus; E. Ovarian follicle in estrus; F. Ovarian blood vessel in estrus; PrF. Primordial follicle; PO. Primary follicle; CL. Corpus luteum; L. Blood vessel; A, D. Masson staining; B, E. PAS staining; C, F. VVG staining 图 5 发情期和乏情期犬卵巢结构 Fig. 5 Structure of dog ovary in estrus and anestrus
2.2 患子宫蓄脓犬子宫和卵巢结构特点

2.2.1 子宫肌层结构特点   患子宫蓄脓时犬子宫外环形肌层肌束排列较为紧密,肌层间填充有较多胶原纤维,单个肌纤维体积增大,胞核呈针锥形位于中央,胞核周围出现空白区域,呈现肿胀状态,胞质淡染(图 6AB)。子宫血管内弹性膜变薄且有断裂,外膜中弹性纤维含量减少(图 6C)。内膜肌层厚度比为1.615 0。

A, B. 患子宫蓄脓时犬子宫肌层;C. 患子宫蓄脓时犬子宫血管层血管;S. 浆膜层;CML; 环肌层;A. HE染色;B. Masson染色;C. VVG染色 A, B. Myometrium of dog uterus with pyometra; C. Blood vessels of vascular layer of dog uterus with pyometra; S. Serosa; CML. Circular muscle layer; A. HE staining; B. Masson staining; C. VVG staining 图 6 患子宫蓄脓时犬子宫肌层结构 Fig. 6 Myometrial structure of dog uterus with pyometra

2.2.2 子宫内膜结构特点   患子宫蓄脓时犬子宫固有层子宫腺在200×镜头下每个视野中的平均数为2~3个;腺管管径较乏情期和发情期大,且形状不规则,腺腔内有少量巨噬细胞和大量中性粒细胞浸润;腺上皮细胞发生空泡变性与胞质增生,细胞边界不清,在基膜处有散在的淋巴细胞(图 7A)。胶原纤维含量较乏情期和发情期少,血管周围无弹性纤维(图 7BC)。在PAS阳性反应中,子宫腺上皮细胞的阳性反应程度较乏情期弱,比发情期强(图 7D)。

A~D. 患子宫蓄脓时犬子宫固有层;E、F. 患子宫蓄脓时犬子宫黏膜;LP. 固有层;UG. 子宫腺;EM. 子宫内膜;A、E. HE染色;B. Masson染色;C. VVG染色;D、F. PAS染色 A-D. Lamina propria of dog uterus with pyometra; E, F. Endometrium of dog with pyometra; LP. Lamina propria; UG. Uterine gland; EM. Endometrium; A, E. HE staining; B. Masson staining; C. VVG staining; D, F. PAS staining 图 7 患子宫蓄脓时犬子宫固有层和黏膜结构 Fig. 7 Structure of the lamina propria and mucous membrane of dog uterus with pyometra

患子宫蓄脓时犬子宫黏膜为单层柱状上皮,胞核呈圆形位于细胞基底,细胞发生空泡样变性;PAS反应集中于黏膜上皮细胞游离面及胞质内(图 7EF)。

2.2.3 卵巢结构特点   患子宫蓄脓时犬卵巢中出现由液体分泌物聚集而成的卵巢囊泡,皮质中可见1~2个大黄体,大量闭锁卵泡,正常卵泡较少(图 8A)。卵巢中胶原纤维含量较正常发情期少。在卵泡透明带处见PAS阳性反应,强度与正常发情期相同(图 8B)。卵巢血管内弹性膜不连续,外膜中含有少量弹性纤维(图 8C)。

A. 患子宫蓄脓时犬卵巢皮质;B. 患子宫蓄脓时犬卵巢卵泡;C. 患子宫蓄脓时犬卵巢血管;PrF. 原始卵泡;PO. 初级卵泡;CL. 黄体;L. 血管;A. HE染色;B. Masson染色;C. VVG染色 A. Ovarian cortex of dog uterus with pyometra; B. Ovarian follicle of dog uterus with pyometra; C. Ovarian blood vessel of dog uterus with pyometra; PrF. Primordial follicle; PO. Primary follicle; CL. Corpus luteum; L. Blood vesse; A. HE staining; B. Masson staining; C. VVG staining 图 8 患子宫蓄脓时犬卵巢结构 Fig. 8 Ovarian structure of dog with pyometra
2.3 LF在正常发情期犬子宫和卵巢中的表达

2.3.1 LF在子宫中的表达   LF主要在子宫腺上皮细胞、子宫黏膜上皮细胞中有表达(图 9A~D)。在子宫腺上皮细胞中,乏情期LF的阳性表达水平高于发情期(P<0.05);在子宫黏膜上皮细胞中,发情期LF的阳性表达水平高于乏情期(P<0.05)(表 1)。

A. 乏情期子宫固有层;B. 乏情期子宫内膜;C. 发情期子宫固有层;D. 发情期子宫内膜;A~D阴性对照分别对应右上角插图;LP. 固有层;UG. 子宫腺;EM. 黏膜上皮;L. 子宫管腔;MF. 黏膜皱襞 A. Lamina propria of uterus in anestrus; B. Endometrium of anestrus; C. Lamina propria of uterus during estrus; D. Estrus endometrium; The negative control is corresponding to the illustration in the upper right corner in A-D; LP. Lamina propria; UG. Uterine gland; EM. Endometrium; L. Uterine lumen; MF. Mucosal fold 图 9 发情期和乏情期犬子宫中LF的表达 Fig. 9 Expression of LF in the uterus of dog during estrus and anestrus
表 1 正常发情期及患子宫蓄脓时犬子宫组织中LF的平均光密度值(x±s) Table 1 The mean optical density of LF in dog uterus in normal estrus and pyometra(x±s)

2.3.2 LF在卵巢中的表达   LF在黄体、卵泡、间质、血管、生殖上皮中均有表达(图 10A~J),且乏情期LF的阳性表达水平显著高于发情期(表 2)。LF在生殖上皮中的表达部位在正常发情期略有不同,表现为乏情期主要集中于生殖上皮细胞核,发情期主要在生殖上皮胞质内有表达(图 10 EJ)。

A~J.LF免疫组化染色,a~j.相应的阴性对照;A~E, a~e.乏情期卵巢;F~J, f~j.发情期卵巢;A、F.卵巢卵泡;B、G.黄体;C、H.髓质;D、I.血管;E、J.生殖上皮 A-J.LF Immunohistochemical staining, a-j.Corresponding negative control; A-E, a-e.Anestrous ovary; F-J, f-j.Estrous ovary; A, F.Ovarian follicle; B, G.Corpus luteum; C, H.Medulla; D, I.Blood vessel; E, J.Germinal epithelium 图 10 发情期和乏情期犬卵巢中LF的表达 Fig. 10 Expression of LF in the ovary of dog during estrus and anestrus
表 2 正常发情期及患子宫蓄脓时犬卵巢组织中LF的平均光密度值(x±s) Table 2 The mean optical density of LF in dog ovary in normal estrus and pyometra (x±s)
2.4 LF在患子宫蓄脓犬子宫和卵巢中的表达

2.4.1 LF在子宫中的表达   LF在中性粒细胞、管腔、子宫腺上皮细胞和黏膜上皮细胞中均有表达(图 11AB)。在子宫腺上皮中,患子宫蓄脓时LF的阳性表达高于发情期(P<0.05)。在子宫黏膜上皮细胞中,患子宫蓄脓时和乏情期表达水平相近(表 1)。

A. 患子宫蓄脓时犬子宫固有层; B. 患子宫蓄脓时犬子宫内膜; 阴性对照分别对应右上角插图;LP. 固有层; UG. 子宫腺; EM. 黏膜上皮; L. 子宫管腔; MF. 黏膜皱襞 A. Lamina propria of dog uterus with pyometra; B. Endometrium of dog with pyometra; The negative control is corresponding to the illustration in the upper right corner; LP. Lamina propria; UG. Uterine gland; EM. Endometrium; L. Uterine lumen; MF. Mucosal fold 图 11 患子宫蓄脓时犬子宫中LF的表达 Fig. 11 Expression of LF in dog uterus with pyometra

2.4.2 LF在卵巢中的表达   LF在黄体、卵泡、间质、血管、生殖上皮中均有表达(图 12 A~F),且患子宫蓄脓时的阳性表达量显著低于乏情期,但高于发情期(表 2)。生殖上皮中LF的表达部位主要集中于生殖上皮胞质基底部。

LF免疫组化染色(A~E),相应的阴性对照(a~e);A~E, a~e.患子宫蓄脓时卵巢;A. 卵巢卵泡;B. 黄体;C. 髓质;D. 血管;E. 生殖上皮 LF Immunohistochemical staining (A-E), Corresponding negative control (a-e); A-E, a-e.Pyogenic ovary; A. Ovarian follicle; B. Corpus luteum; C. Medulla; D. Blood vessel; E. Reproductive epithelium 图 12 患子宫蓄脓时犬卵巢中LF的表达 Fig. 12 Expression of LF in dog ovary with pyometra
3 讨论

雌激素和孕酮是重要的生殖激素。在发情前期、发情期卵泡发育过程中,卵泡颗粒细胞会分泌并释放雌激素,子宫及生殖道在雌激素的作用下发生充血、黏膜层增厚、黏膜上皮增生、管状腺体长度增加、分泌增强等生理反应。当成熟卵泡破裂排卵后,卵泡颗粒细胞分化成粒性黄体细胞,形成黄体并分泌孕酮。正常情况下,孕酮可以促进子宫内膜层增生增厚,减弱子宫平滑肌层的运动,抑制子宫内局部免疫作用。本研究发现,患子宫蓄脓时犬卵巢出现持久黄体,这与Bostedt等[19]研究结果相同。而持久黄体使得卵巢不断分泌孕酮,从而使血清中孕酮浓度持续升高,高浓度孕酮将抑制抗原递呈细胞的成熟,降低白细胞抵抗细菌感染的能力[20],加之雌激素使子宫颈开放、子宫内膜增生、子宫腺分泌增加,最终使子宫腺体囊性增生,为病原菌的侵入及繁殖创造了条件。

在犬发情周期各阶段的更迭过程中,随激素及其他影响因子的变化,犬子宫组织结构也随之发生相应改变[21]。本研究发现,犬在发情期的内膜肌层厚度比大于乏情期,与许琴等[8]结果相一致,这可能与乏情期子宫肌层中雌激素受体水平较发情期高有关[10]。当犬发生子宫蓄脓时,内膜肌层厚度比进一步增加,且显著高于发情期,这可能是由于子宫内膜囊性增生所致[22]。通常在发情期到发情后期,犬子宫腺细胞体积逐渐增大,子宫腺体高度盘旋,随后子宫腺细胞体积迅速缩小,子宫腺腔明显表现出子宫腺囊性增生(CEH)[23]。本研究同时还发现,乏情期和发情期犬的子宫黏膜上皮形态结构存在明显差异。发情期犬子宫黏膜上皮细胞呈现独特的泡沫状形态,且四周分布有较多隐窝,此特征与Marinkovi c ′等[24]的报道相同,分析是由于大量脂滴聚集于上皮细胞而形成[25]。当犬患有子宫蓄脓时,子宫黏膜上皮细胞以病理性空泡样变性为主要特征,这与Singh等[26]的观察结果相一致。

由于子宫腺分泌细胞能合成糖原、中性黏多糖、酸性黏多糖及脂类等物质[27],利用PAS反应可观察到腺细胞的分泌活动。本研究通过此方法对犬正常发情期与患子宫蓄脓时糖原在子宫和卵巢中的分布进行了观察,发现在子宫黏膜上皮细胞中,发情期黏膜上皮细胞的游离面和基底面均有PAS阳性反应,这与Gregoraszczuk等[28]研究结果相似。在子宫固有层中,乏情期腺上皮细胞游离面可见PAS强阳性反应,发情期中只有少量PAS阳性反应,这与Stroband等[29]对雌性周期和早期妊娠期间猪子宫上皮的PAS观察结果相似。当犬患有子宫蓄脓时,糖原不规律的分布在细胞游离缘,这可能是由于炎性产物对上皮细胞结构的破坏,导致糖原分泌下降及无规律的分布[30]。正常发情期和患子宫蓄脓时犬卵巢PAS反应在透明带处均呈阳性且强度相同,说明透明带在上述情况下分泌和合成糖原的程度相同。

LF是一种具有多种生理活性的天然蛋白质,不仅是乳腺组织分泌的非特异性保护蛋白质,还存在于如泪、汗、唾液、胆汁、胰液、小肠腺液等外分泌物中[10]。LF具有广谱的抗菌活性[31],同时还具有调节巨噬细胞活性和刺激淋巴细胞合成的能力,对抗体生成、T细胞成熟、淋巴细胞中自然杀伤细胞比例均具有调节作用[14]。本研究发现,LF在子宫腺上皮细胞、子宫黏膜上皮细胞和患子宫蓄脓时的中性粒细胞,以及在卵巢黄体、卵泡、间质、血管、生殖上皮中均有表达,这与Kolm等[15]的观察结果相一致。同时,本研究还发现在子宫黏膜层中,发情期LF的阳性表达水平高于乏情期,这与Tsumagari等[32]将大肠杆菌接种到出现黄体生成素波前的母犬中,经12 d后并再次恢复的结果相吻合。在发情期LF阳性表达水平高,且此时发生子宫蓄脓的概率较小,可能是由于LF在黏膜分泌物中具有较强铁结合能力和使局部形成相对无铁状态,这有助于黏膜表面的天然免疫反应,从而限制了大多数病原体包括大肠杆菌的入侵和感染[33]

4 结论

本研究运用组织学、组织化学及免疫组化技术,对正常发情期与患子宫蓄脓时犬子宫与卵巢的组织结构及LF的表达情况进行了研究。发现子宫内膜肌层比在犬患子宫蓄脓时最大,发情期次之,乏情期最小;从乏情期到发情期,子宫腺管腔逐步扩大,腺细胞体积缩小;当犬患有子宫蓄脓时,子宫腺腺管管径进一步扩大,内有中性粒细胞浸润;LF在子宫腺上皮细胞、子宫黏膜上皮细胞和患子宫蓄脓时的中性粒细胞,以及在卵巢黄体、卵泡、间质、血管、生殖上皮中均有表达。

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