Comalli M P, Eberhart R J, Griel L C, Rothenbacher H
Am J Vet Res. 1984 Nov;45(11):2236-42.
Changes in the microscopic anatomy of the bovine teat canal were examined during mammary involution. Morphometric analyses revealed a significant (P less than 0.05), temporary dilatation of the teat canal lumen on day 7 of the nonlactating period. Additionally, the teat canal epithelium physiologically atrophied as evidenced by decreased cross-sectional area and thickness during the first 30 days of the nonlactating period, significantly so (P less than 0.05) between days 0 and 7. This physiologic atrophy was due mainly to a reduction in area and thickness of the stratum granulosum and may have resulted from continuing keratinization, a process that led to increased thickness of the keratin layer and formation of a functional plug during later stages of involution. Changes in cells of the stratum granulosum indicated a decrease in the rate of epithelial cell maturation during involution. The mitotic index (percentage of basal cells in mitosis) of the teat canal epithelium decreased significantly (P less than 0.05) between days 0 and 7 of the nonlactating period. Bacteria, observed in histologic sections, appeared to colonize only certain regions of the keratin layer. Seemingly, changes in the teat canal during mammary involution may be important factors in changing susceptibility to new intramammary infection during the early and mid-nonlactating periods.
在乳腺退化过程中，对牛乳头管的微观解剖结构变化进行了研究。形态计量学分析显示，在非泌乳期第7天，乳头管腔出现显著（P<0.05）的暂时扩张。此外，乳头管上皮在非泌乳期的前30天出现生理性萎缩，表现为横截面积和厚度减小，在第0天至第7天之间差异显著（P<0.05）。这种生理性萎缩主要是由于颗粒层面积和厚度的减少，可能是由于持续的角质化导致的，角质化过程在退化后期导致角质层增厚和功能性栓子的形成。颗粒层细胞的变化表明在退化过程中上皮细胞成熟速率降低。非泌乳期第0天至第7天之间，乳头管上皮的有丝分裂指数（处于有丝分裂的基底细胞百分比）显著降低（P<0.05）。在组织学切片中观察到的细菌似乎仅在角质层的某些区域定植。显然，乳腺退化过程中乳头管的变化可能是在非泌乳早期和中期对新的乳房内感染易感性变化的重要因素。
