Reproduction and Development in Chondrichthyan Fishes
Reproduction and Development in Chondrichthyan Fishes
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软骨鱼类的繁殖和发育
DOI：
10.1093/icb/17.2.379
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发表时间：
1977
影响因子：
2.6
通讯作者：
J. P. Wourms
中科院分区：
文献类型：
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作者：
J. P. Wourms
软骨鱼的繁殖和发育模式是多样的。物种要么全年繁殖活跃，要么有一个不明确的年周期，只有一个或两个活动高峰，要么有一个明确的年或两年周期。根据胚胎起源和成体形态，它们的生殖系统更类似于四足动物而不是硬骨鱼。原始生殖细胞起源于内胚层。男性的沃尔夫管和女性的缪勒管成为功能性的泌尿生殖道。分化是由激素控制的。生殖系统的不寻常特征包括男性和女性都有一个外阴器官。它含有淋巴组织和造血组织。睾丸腺是肾脏的一个修饰区域，产生精液。在一些物种中，通过输精管的精子被包裹在精子囊中。螺旋精子围绕其长轴旋转，可以向前或反向移动。精子发生通常发生在双细胞单位，即精子囊中。这些细胞包括被包裹在Sertoh细胞中的精原细胞。受精是内部的。鳍片，腹鳍的修饰部分，作为隐蔽性器官。在许多胎生鲨鱼和鳐鱼中，雌性生殖系统是不对称的。一些鲨鱼的卵是已知最大的细胞。卵黄血小板含有脂蛋白。卵母细胞有灯刷染色体。卵子从卵巢释放到体腔，通过纤毛作用到达输卵管口。它们在那里受精。生理性多精是正常的。壳腺是输卵管前部的一个特殊区域，在长期储存精子和产生卵子方面都起作用。鲨鱼和溜冰鞋的卵壳由独特的胶原蛋白组成，具有400 a周期，组织为胆固醇液晶。嵌合体卵壳在正交晶格中含有550个A假小管。在小鲨鱼中，雄鲨盘绕在雌鲨周围交配。大型鲨鱼会采取平行的姿势。鳐鱼和鳐鱼以腹面相对或通过背侧方式交配。咬是交配前的一种释放机制。除了选择性产卵外，缺乏亲代照顾。蛋黄含量高的鸡蛋经历成元细胞的盘状卵裂。发育过程漫长，鳐鱼最短（2-4个月），鳐鱼较长（3-8个月），鲨鱼和嵌合体最长（9-22个月）。大多数鲨鱼和所有鳐鱼都是胎生的。chimera， skate和一些鲨鱼是卵生的。胎生包括卵黄囊胎盘或胎生胎盘。如果是胎盘，胚胎要么从卵黄储备中获取营养，要么通过子宫内胚胎的同类相食，要么从分泌“子宫乳汁”的胎盘类似物中获取营养。系统发育位置、地理分布、底栖与远洋生境、成虫大小、卵胚大小、摄食生态和胚胎渗透调节是影响卵泡保留或胎生进化的因素。
Patterns of chondrichthyan reproduction and development are diverse. Species either are reproductively active throughout the year, or have a poorly defined annual cycle with one or two peaks of activity, or have a well defined annual or biennial cycle. Based on embryological origin and adult morphology, their reproductive system is more similar to tetrapods than to teleosts. Primordial germ cells are of endodermal origin. The Wolffian ducts in males and Mullerian ducts in females become the functional urogenital ducts. Differentiation is under hormonal control. Unusual features of the reproductive system include an epigonal organ in males and females. It contains lymphoid and hemopoietic tissue. Leydig's gland, a modified region of the kidney, produces seminal fluid. In some species, sperm passing through the vas deferens, is enclosed in spermatophores. Rotating about their long axis, helical spermatozoa can move forward or reverse direction. Spermatogenesis often occurs in bicellular units, spermatocysts. These consist of a spermatogonium enclosed in a Sertoh cell. Fertilization is internal. Claspers, modified portions of the pelvic fins act as intromittent organs. In many viviparous sharks and rays, the female reproductive system is asymmetrical. Eggs of some sharks are the largest known cells. Yolk platelets contain lipovitellin. Oocytes have lampbrush chromosomes. Eggs released from the ovary into the body cavity are transported by ciliary action to the ostium of the oviduct. There they are fertilized. Physiological polyspermy is normal. The shell gland, a specialized region of the anterior oviduct, functions both in long term sperm storage and in egg case production. Egg cases of sharks and skates consist of unique collagenous protein with a 400 A period, organized as a cholesteric liquid crystal. Chimaeroid egg cases contain 550 A pseudotubules in orthogonal lattices. In small sharks, males copulate by coiling around the female. A parallel position is assumed by large sharks. Skates and rays copulate with ventral surfaces apposed or by a dorsal approach. Biting is a pre-copulatory release mechanism. Parental care, except for selective oviposition, is lacking. Heavily yolked eggs undergo meroblastic, discoidal cleavage. Development is lengthy, shortest (2–4 months) in rays, longer in skates (3–8 months) and longest (9–22 months) in sharks and chimaeras. Most sharks and all rays are viviparous. Chimaeras, skates, and some sharks are oviparous. Viviparity either involves a yolk sac placenta or is aplacental. If aplacental, the embryo derives nutrients either from yolk reserves, or by intra-uterine embryonic cannibalism, or from placental analogues which secrete “uterine milk.” Phylogenetic position, geographical distribution, benthic vs. pelagic habitat, adult size, egg-embryo size, feeding ecology, and embryonic osmoregulation are factors in the retention of oviparity or the evolution of viviparity.