Liu Jianan, Elsasser Theodore H, Long Julie A
Animal Biosciences and Biotechnology Laboratory, Agricultural Research Service, US Department of agriculture, Beltsville, Maryland 20705, USA.
J Poult Sci. 2017 Oct 25;54(4):303-311. doi: 10.2141/jpsa.0170033.
The objectives of this study were to examine morphological changes of oogonia and primordial follicles in the ovaries of turkey poults within the first week after hatching, and to evaluate the effect of cryopreservation on histology and apoptosis of these immature ovaries. Ovaries from poults at Day 1, Day 3, Day 5 and Day 7 post-hatch were cryopreserved using a modified vitrification method. The histology of oogonia and primordial follicles in fresh and cryopreserved tissue was assessed, and the apoptosis of tissue in different age groups was identified using a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The mean oogonium diameter in fresh tissue increased from 11.9±1.3 m (Day 1) to 15.2±2.7 m (Day 7) within the first week; however, oogonia in cryopreserved tissue from Day 3 and Day 7 ovaries were smaller than those in fresh tissue (<0.05). Formation of primordial follicles was observed as early as Day 5. For Day 7 ovaries, follicles in cryopreserved tissue were smaller than those in fresh tissue; this was also true for oocyte diameter (<0.05). Apoptosis was most frequent in Day 1 fresh tissue, which was reduced as the poults aged. The frequency of apoptosis in cryopreserved tissue was comparable among age groups. This study provides the first documentation of morphological changes in the turkey ovary within the first week post-hatching. Results suggest that oogonia and primordial follicles that are smaller in size could be more resistant to the damage caused by cryopreservation. Of the ages assessed in this study, it is concluded that 3 days of age appears optimal for recovery of donor ovaries for cryopreservation, taking the advance of reduced cryoinjury and ease of tissue handling at this age.
本研究的目的是检查孵化后第一周内火鸡雏鸡卵巢中卵原细胞和原始卵泡的形态变化，并评估冷冻保存对这些未成熟卵巢组织学和细胞凋亡的影响。采用改良玻璃化方法对孵化后第1天、第3天、第5天和第7天的雏鸡卵巢进行冷冻保存。评估新鲜组织和冷冻保存组织中卵原细胞和原始卵泡的组织学，并使用末端脱氧核苷酸转移酶dUTP缺口末端标记（TUNEL）法鉴定不同年龄组组织的细胞凋亡情况。新鲜组织中卵原细胞的平均直径在第一周内从11.9±1.3μm（第1天）增加到15.2±2.7μm（第7天）；然而，第3天和第7天卵巢冷冻保存组织中的卵原细胞比新鲜组织中的小（<0.05）。最早在第5天观察到原始卵泡的形成。对于第7天的卵巢，冷冻保存组织中的卵泡比新鲜组织中的小；卵母细胞直径也是如此（<0.05）。细胞凋亡在第1天的新鲜组织中最为频繁，随着雏鸡年龄的增长而减少。冷冻保存组织中细胞凋亡的频率在各年龄组中相当。本研究首次记录了孵化后第一周内火鸡卵巢的形态变化。结果表明，较小的卵原细胞和原始卵泡可能对冷冻保存造成的损伤更具抵抗力。在本研究评估的年龄中，得出结论，考虑到这个年龄冷冻损伤减少且组织处理容易，3日龄似乎是冷冻保存供体卵巢恢复的最佳年龄。
