| This experiment aimed to study the thymus aging-related changes of female Anhuai white goats based on thymus morphological observation and gene mRNA level of detection.Each period of three infancy(7 D),pre-pubertal(3.5 M),pubertal(5 M)and adulthood(18 M)female Anhuai white goats were obtained for this experiment.Fresh tissue samples of the cervical and thoracic thymus were collected from goat in different developmental periods,and the weight,length and index of thymus were recorded.Histological section technique was used to observe the structure of thymus under a microscope.Immunohistochemical technique was used to explore the distribution of S100 protein and apoptosis protein named Caspase-3 in thymus.In addition,the level of S100,CASP-3,CASP-8 and TP53 mRNA of goat thymus in different periods were detected with real-time fluorescent PCR technology.So the age-related thymic change was explored in female goat.Results:(1)The length and weight of thymus increased significantly after birth(P<0.05),peaked at pubertal period,and then declined significantly in adulthood period(P<0.05),but still significantly higher than the infancy period(P<0.05);the thymus index and the widest of thymus increased significantly from infancy to pre-pubertal(P<0.05),subsequently reduced,and reach the lowest in adulthood;the length ratio of thoracic/cervix segments had a significantly decreased trend from infancy to pre-pubertal(P<0.05),there was no significant difference between pre-pubertal and pubertal period,and between adulthood and the other periods(P>0.05).(2)The observation of histology of thymus cervix segment showed that the thymus of infancy period has no obvious junction between cortex and medulla,and there was the clear difference between cortex and medulla at pre-pubertal,pubertal and adulthood;the tissue cell density decreased gradually along with the aging,and cortical area density was higher than the medulla area;the cortex gradually thinning and medulla area proportion increased significantly with aging.Similar results were observed in thymus thoracic segments.(3)Caspase-3 and S100 protein positive cells distributed mainly in the cervical and thoracic of thymus in four different periods;the Caspase-3 positive cells located in the cortex and medulla of thymus,but the S100 mainly distributed in the cortex and medulla junction and medulla;Caspase-3 positive cells increased markedly with aging(P<0.05);the infancy positive cells was significantly less than the other period(P<0.05),but there was no significant difference among the pre-pubertal,pubertal and adulthood period.(4)No significant difference was found in level of S100 mRNA between different periods(P>0.05);the level of CASP-3 mRNA in pre-pubertal was significantly higher than the other period(P<0.05);the level of CASP-8 mRNA increased since infancy to pre-pubertal period(P<0.05),and then reduced in pubertal period(P<0.05),but there was no significant difference between adulthood and the other periods(P>0.05);there was also no significant difference in level of TP53 mRNA between infancy and pre-pubertal and pubertal(P>0.05),but there was a significant increase in adulthood(P<0.05).Conclusion:(1)The thymus of female goat grows from infancy to pubertal period,and peaks at pubertal,then degrades with aging.(2)The TDCs marked by S100 protein mainly distributes in medulla area,cortex and medulla junction of thymus,however,Caspase-3 protein positive cells locates in the cortex,medulla and the cortex and medulla junction.(3)CASP-3 and CASP-8 may participate in early stage of thymus development and cell renewal and early stage involution process of thymus,and CASP-8 and TP53 may play an important role in thymus involution during adulthood. |
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