Studies On The Structure And Function Of Male And Female Reproductive System And Spermatophore Artifical Transfer Of The Mud Crab Scylla Serrata (Forsk(?)l)

Scylla serrata is a commercially important marine crab in China. To help elucidate its reproductive characteristics,the functional anatomy of the male reproductive system and the female spermathecae are investigated using the histological techniques, transmission and scanning electron microscopy, and microscopic observaion of fresh material, focusing on sperm transfer, sperm storage in the seminal receptacles, and spawning. The results were as follow:1. The development of spermatophore begins from testicular.The testicular secretes substance which agglutinates the dissociate mature spermatozoa or sperm cell and forms the primary spermatophore layer. Closed to testicular is the anterior portion of the proximal vas deferens which continues its agglutination of spermatozoa and separate the sperm mass gradually .The secretory nature changes in the distal part of the proximal vas deferens in that a granular substance is released to constitute the medium for storing the completed spermatophore. The middle vas deferens is membranous and acts as the storage region for the seminal products. The distal vas deferens interspace between middle vas deferens and ejaculatory duct. Following the short distal vas deferns is the long ejaculatory duct, its fluid-like secretion is not mixed with the rest of the semen stored in the mid vas deferens until the time of mating. In view of the mucoid nature of this secretion, it may function as the accessary gland.2. A pair of androgenic glands attach to the distal part of the ejaculatory ducts of Scylla serrata. Androgenic gland is connected to the fifth pereiopod nerve of thoracic ganglion directly. This nerve also concomitant with edjaculatory ducts between the muscles of fifth walking leg and may control the spermatophore expulsion.3. The sperm of Scylla serrata has several nuclear arms. Large numbers of sperm become clumped into aggregates which surrounded by an acellular wall secreted by cells of the anterior vas deferens. As the sperm move posteriorly,this thin wall becomes surrounded by yet another epithelial secretion which condenses against it .Together the two layers form the definitive spermatophore wall which apparently differ in electron density of the composing material. The spermatophores of Scylla serrata are ellipsoidal in shape and consists of sperm mass and matrix. Numerous spermatophores are stored in the median regions of the vas deferens where they become mixed with seminal fluids .The seminal fluid which surrounds the spermatophores appears flocculent and globular nature. The spermatophores show two different morphological types: one with an extremely wrinkled spermatophoric wall which are stored in the spermathecae and the other with smooth and thin spermtophoric wall which are used for immediate fertilization of oocytes at copulation. Many microvilli are seen on the inner surfaces of epithelial cells of median vas deferens and ejaculatory duct.There are many secretions on the top of the microvilli.4. The ejaculatory duct of Scylla serrata open on the coxae or sternum of eighth segment by short muscular penis. The first gonopod consists of a basal protopodite and elongated endopodite.in which the cuticle is infolded the entire length a tube which functions as an ejaculatory canal. The second pleopod fits into this cuticular fold, while the penis fits into a slit on the lateral side at the base of the endopodite. During coitus, seminal substances are ejected by muscular action through the penis into the ejaculatory canal of the first pleopod. The ejaculate is further pushed down the canal by the pumping action of the piston-like second pleopod. The first gonopod terminates in a recurved process, at the apex of which the ejaculatory canal opening forms a distinct spout, the cuticular fold are easily distinguished as outer and inner folds and form the lateral slot. Several types of setae are quite conspicuous on the first and second gonopod. There are also some long processes and setae on the lateral slot .Pinnate se...