A variety of biology events occur during spermatogenesis , such as self - renewal of spermatogonia , meiotic division of spermatocyte and the spermiogenesis of spermatid 生精过程中发生了许多生物学的变化，如精原细胞的自我更新，精母细胞的减数分裂和精子细胞的变形。
Spermatogenesis macrobrachium rosenbergii during spermatogenesis , chromatins keep on condensing until mid - spermatid stage . the nucleus changes into two forms : fibrous and homogeneous forms 精子发生罗氏沼虾精子发生过程中染色质凝集程度逐渐增大，至精细胞中期凝集程度达到最大。
So a lagre populations of relatively purified spermatids can be isolated from mouse testis by enzymatic digestion combined with discontinuous percoll gradient centrifugation method 因此采用组合酶消化结合非连续percoll梯度离。 g法，可有效地从小鼠睾丸中分离到较多较纯的存活精子细胞。
However , the rates of fertilization and pregnancy with spermatids have been disappointing . many problems limiting success rates and binding a wide application of this technique still remain unresolved 但精子细胞的受精率和妊娠率令人失望，限制这项技术成功和阻碍其临床应用的许多问题仍然没有解决。
The nucleus has two forms at the middle spermatid stage : fibrous one and condensed one . the nucleus extends into the radial arm . the number of organelles keeps increasing until secondary spermatocyte stage 与已有的报导不同的是，我们发现精原细胞分为两类，其中i类精原细胞经过分化形成n类精原细胞。
Sustentacular cell was at the exterior margin of spermatogenous . in v testis , seminiferous epithelium had spermatozoon , spermatid and sustentacular cell . the sustentacular cell was fat and full of particle 支持细胞位于性细胞团的外缘，对生精细胞起支持和营养作用;在v期精巢内，精细管由大量的精子、少量的精子细胞和支持细胞构成。
Therefore there is a need to develop a method by which large and purified populations of spermatids can be isolated , not only for the immediate requirement but also for cryoproservation for subsequent treatment cycles 因此，有必要建立一种比较简单的、可获取大量纯化精子细胞的方法，不但可满足立即使用所需，也可进行冷冻保存用于以后的治疗周期。
According to the changes of the structure of chromatin and the morphology of cell , the process of the typical spermatogenesis of cipangopaludina chinensis can be divided into five stages : spermatogonium , primary spermatocyte , secondary spermatocyte , spermatid and mature sperm 中国圆田螺典型精子发生时，根据染色质和细胞形态的变化，可将其发生分为以下五个时期：精原细胞、初级精母细胞、次级精母细胞、精细胞和成熟精子。
Portunus , trituberculatus the spermatogonium exist in two different forms , the second form comes from the first one . during spermatogenesis , chromatins condense at different level . the nucleus changes into homogeneous since middle spermatid stage , and the nucleus extends into the radial arm 三疣梭子蟹在生精细胞阶段，染色质不同程度的浓缩凝集；在精细胞阶段，核质呈均质状，形成薄壁的圆球形核杯，部分核质延伸入辐射臂内。
Most commonly used is the mechanical method in which a small piece of testicular tissue is torn apart using needles and the spermatids are released . while enzymatic digestion of human testicular tissue can result in a mixture of cell types including a whole range of spermatogenic cell types 最常用的是机械方法，即利用细针将活检获得的小块睾丸组织撕开，释放出精子细胞；也可利用酶将睾丸组织消化成细胞悬液，其中包含所有类型的生精细胞。
