Morphology of the female genital ducts of the blue land crab Cardisoma guanhumi (Crustacea: Brachyura: Gecarcinidae)

This is a histological and histochemical analysis of the terminal portion of the female reproductive system and genital ducts of the blue land crab (Cardisoma guanhumi). Animals were collected in the Jaguaribe estuary (Ceará, Brazil) and dissected. Genital duct fragments were fixed and submitted to different staining techniques. The female reproductive system consists of a pair of ovaries and a pair of genital ducts. In the mid‐posterior portion of each lobe, the ovaries communicate with the genital ducts, which are subdivided into oviduct, spermatheca, vagina, and gonopore. Histologically, the spermatheca of C. guanhumi is composed of columnar secretory epithelium and is divided into a dorsal zone and a ventral zone, the latter covered internally by a cuticle layer. Both zones are enveloped by a thin layer of loose connective tissue. Histological cross sections revealed the vagina to be concave, a pattern considered phylogenetically more advanced than the simple, tubular form. Our findings suggest fertilization is internal, favoring sperm from the most recent copulation.     

Development of the accessory reproductive glands and genital ducts in female Schistocerca gregaria

The accessory reproductive glands of female S. gregaria are tubular extensions of the paired genital ducts, which in the mature female contain large amounts of a proteinaceous secretion used in the formation of the egg pod. In the 4th and 5th-instar female the glands are indistinguishable from the remainder of the mesodermally derived genital ducts. Towards the end of the 5th stadium, however, the accessory gland region only acquires characteristic convolutions which persist throughout the adult stages. At this time the epithelium of the entire ducts becomes reorganized into a unicellular epithelium. Only one cell type occurs throughout the length of the glands, and also in the egg calyces and lateral oviducts. The cells are inactive immediately after final ecdysis and remain in this state until the level of juvenile hormone in the haemolymph rises. The hormone acts directly on the cells triggering a rapid proliferation of organelles associated with protein secretion, and thereby increasing the volume of apical cytoplasm. Microvilli develop at the luminar plasma membrane, while irregular infoldings form at the base of the cells. As the gland matures the major organelle, the rough endoplasmic reticulum, changes from the lamellar to the vesicular form. Secretion is released into the lumen by the ‘microapocrine’ method.     

Ultrastructure of genital system ducts of Diphyllobothrium latum (Cestoda:Pseudophyllidae): the ducts of the female reproductive system

The components of the female reproductive system of Diphyllobothrium latum, including ovary, ovicapt, oviduct, vitelline ducts, vitelline reservoir, vagina, seminal receptacle, ootype with unicellular Mehlis's gland, ootype-uterine duct and uterus were observed with the electron microscope. The epithelium of the female reproductive system ducts consists of a nucleate syncytial layer. Structural differences in apical surface of the ducts, the number of nuclei and organoids in syncytial layer as well as the number of underlaid muscles were revealed. The regional differentiations of the uterus wall were registered. The middle and distal region of uterus was covered with microtriches. The filamentous microtriches were observed in apical surface of vagina. The epithelium of seminal receptacle and distal region of uterus were underlaided by the powerful muscle layers. The fertilization canal was revealed. It was shown that the formation of egg shells implemented by the deposit of vitelline globules in their surface in the ootype-uterine duct. Structural and functional differences of different parts of female apparatus in various groups of cestodes are conditioned by species biology.     

The role of the accessory reproductive glands and genital ducts in egg pod formation in female Schistocerca gregaria

Removal of the accessory reproductive glands in female Schistocerca gregaria does not prevent the formation of eggplugs as expected. The egg pods formed are incomplete, with froth in the egg plug partially lacking. The extent of collapse is dependent on the time of removal of the glands. These results suggest that the genital ducts (egg calyces and lateral oviducts) play a significant role in the production of egg pod material, and the accessory glands probably participate in the process. Ligation of the glands has the same effect on egg pod structure; secretion accumulates in the glands indicating that, although the contribution made to the egg pod by the glands is small, they are not vestigial and are not acting simply as reservoirs for secretions produced distally. Cautery of the Comstock-Kellogg glands produces no visible change in egg pod structure or in method of formation, and thus their function remains undetermined. In the absence of the ventral median pouch egg masses are laid without the plug. A thin layer of nonvacuolated material is smeared over the walls of the oviposition hole, suggesting that the secretions produced in the upper regions of the genital ducts are added to or modified by an additional secretion from this gland, before being released to the exterior.     

Developmental process of genital ducts in the medaka, Oryzias latipes

The morphological development of genital ducts both intra-gonadal (ovarian cavity and efferent duct) and extra-gonadal (oviduct and sperm duct) was investigated in a model teleost, medaka Oryzias latipes. The results showed that the extra-gonadal genital ducts contained two structural units, the anterior and posterior parts, in both sexes. Of special interest is a newly discovered process for the development of a posterior part of the oviduct. The anterior part of oviduct extended continuously from the ovarian cavity at the posterior end of the ovary. Then the posterior part of oviduct, which termed genital pore lip (GPL) in this study, was formed. This part results from invagination and cavitation of the cortex of urinogenital papillae (UGP) and forms the wall of the oviduct opening. We also suggest that the ventral region of urethra mesenchyme has an important role in extra-genital ducts formation.     

Morphology of the female reproductive system of European pea crabs (Crustacea,Decapoda, Brachyura,Pinnotheridae)

Commensal pea crabs inhabiting bivalves have a high reproductive output due to the extension andfecundity of the ovary. We studied the underlying morphology of the female reproductive system in the Pinnotheridae Pinnotheres pisum, Pinnotheres pectunculi and Nepinnotheres pinnotheres using light microscopy and transmission electron microscopy (TEM). Eubrachyura have internal fertilization: the paired vaginas enlarge into storage structures, the spermathecae, which are connected to the ovaries by oviducts. Sperm is stored inside the spermathecae until the oocytes are mature. The oocytes are transported by oviducts into the spermathecae where fertilization takes place. In the investigated pinnotherids, the vagina is of the “concave pattern” (sensu Hartnoll 1968 ): musculature is attached alongside flexible parts of the vagina wall that controls the dimension of its lumen. The genital opening is closed by a muscular mobile operculum. The spermatheca can be divided into two distinct regions by function and morphology. The ventral part includes the connection with vagina and oviduct and is regarded as the zone where fertilization takes place. It is lined with cuticle except where the oviduct enters the spermatheca by the “holocrine transfer tissue.” At ovulation, the oocytes have to pass through this multilayered glandular epithelium performing holocrine secretion. The dorsal part of the spermatheca is considered as the main sperm storage area. It is lined by a highly secretory apocrine glandular epithelium. Thus, two different forms of secretion occur in the spermathecae of pinnotherids. The definite role of secretion in sperm storage and fertilization is not yet resolved, but it is notable that structure and function of spermathecal secretion are more complex in pinnotherids, and probably more efficient, than in other brachyuran crabs. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

Morphology of female genital tracts in Dasypodidae (Xenarthra,Mammalia): a comparative survey

Previous works about comparative spermatology in Dasypodidae determined that sperm morphology is a striking variable among genera. It was suggested that this sperm feature may be related to specific morphologies of the female reproductive tract. The present comparative study of the morphology of the female genital tract from seven species corresponding to six genera of Dasypodidae is aimed to determine the main similarities and differences between the species and to establish a possible correlation with the sperm shapes and sizes. Genital tracts were studied macroscopically and histologically. Dasypus hybridus has disk-shaped ovaries and the cortex occupies almost all the organ with a single oocyte in each follicle. Tolypeutes matacus, Chaetophractus villosus, Chaetophractus vellerosus, Zaedyus pichiy, Cabassous chacoensis and Clamyphorus truncatus possess ovoid and elongated ovaries, with both longitudinally polarized cortex and medulla, and the peculiar presence of several oocytes in the same follicle. D. hybridus and T. matacus have a simple pear-shaped uterus, but in the other species the uterus is pyramid shaped and bicornuate. The uterine cervix is very long in all studied species. Only T. matacus presents a true vagina as in most eutherian mammals; on the other hand, in the other species a urogenital sinus is observed. The structure of female reproductive tracts in Dasypodidae contains a mixture of assumedly primary and other derived features. According to the different morphologies of the regions analyzed, a classification of the female genital tracts in three groups can be performed (group 1: Dasypus; group 2: Tolypeutes; group 3: Chaetophractus, Zaedyus, Cabassous, Clamyphorus) and a correlation between each group and a specific sperm morphology can be established.     

Developmental changes in interstitial collagens of fetal rat genital ducts

The distribution of interstitial collagen types I and III was studied by immunocytochemistry in the mesenchyme of progressing and regressing mesonephric and paramesonephric ducts of male and female rat fetuses from the age of 15 days until birth. Immunocytochemistry revealed a collagen-poor mesenchymal area around the genital ducts and in continuation with the coelomic epithelium on the lateral edge of the mesonephric ridge of 15-day-old fetuses. Ultrastructurally, collagen fibrils were accumulated along the continuous lamina densa of the mesonephric ducts, whereas they were absent on the medial side of the male and female paramesonephric ducts. In males, the amount of collagen fibrils increased with the histological maturation of the mesenchyme around the mesonephric duct, whereas around the regressing paramesonephric duct collagens disappeared from the basement membrane region and the surrounding mesenchyme of the 16-day-old male duct. After the completion of the paramesonephric regression, the mesenchyme acquired a uniformly collagen containing interstitial matrix. In females, the collagens increased in the mesenchyme around the progressing paramesonephric duct, and the original site of the regressing mesonephric duct became occupied with a collagen-containing mesenchyme by the age of 19 days. The results suggest a close structural linkage between the mesonephric duct and the established early paramesonephric duct. The differences in the developmental maturation of the periductal mesenchyme and the observed changes in the composition of the interstitial matrix probably reflect the functional differences in the regulatory factors acting on the progression and regression of the male and female genital ducts.     

Development of the genital ducts in Telmatodrilinae (Tubificidae, Clitellata)

In Tubificidae, the male genital duct comprises a funnel in the testes segment, followed by a vas deferens, an atrium, and, frequently, a copulatory structure in the adjacent ovarian segment. There may also be a diffuse or compact prostate gland in association with the duct. The morphology and position of the genital ducts are important for the classification of the oligochaetous Clitellata. Different parts of the male duct, however, have been named without regard to whether they are homologous or not. One way to establish better hypotheses of homology is to study the detailed morphology and/or the development of the genital ducts. The morphogenesis of the genital ducts in Alexandrovia onegensis (Telmatodrilinae) is described. The male funnel originates by multiplication of peritoneal (mesodermal) cells in the posterior septum in the testes segment. A cord of these cells breaks through the septum and grows backwards into the next segment, where it connects to the epidermis. This cord gives rise to the vas deferens, and is therefore mesodermal in origin. The atrium in A. onegensis develops from a primary epidermal (ectodermal) invagination. The vas deferens and atrium connect and a continuous duct from the testes segment to the exterior is formed. Several compact prostate glands develop along the atrium, each being formed from cells in the atrial epithelium. The spermatheca develops from an invagination of the epidermis in the testes segment. The female duct is formed from peritoneal (mesodermal) cells in the posterior septum in the ovarian segment. These developmental findings strengthen the hypothesis about a closer relationship between the Telmatodrilinae and Tubificinae (both Tubificidae).     

Ultrastructure of the male genital ducts of the clearnose skate Raja eglanteria

Tissues from the male genital ducts of six specimens of the clearnose skate Raja eglanteria, comprising the Leydig gland, upper and lower epididymis, ductus deferens and seminal vesicle, were fixed and embedded for ultrastructural examination. In the Leydig gland, two types of columnar cells were identified, one bearing microvilli, a basal nucleus and evidence of active secretion with plentiful endoplasmic reticulum and numerous secretory droplets, and the other pyriform with cilia, and swathes of cytofilaments emanating from prominent desmosomes. Occasional crystalloid intramitochondrial inclusions were seen in the first type, with a periodicity of 24 nm. The upper epididymis was composed of cuboidal cells with microvilli and cilia and irregular electron dense granules, some of which were basally situated and extremely large, often within cells resembling intraepithelial leucocytes; such cells were also seen in the stroma underlying the epithelium. The lower epididymis cells also bore microvilli and cilia and were heavily vacuolated with fatty inclusions as well as the granule-laden leucocytes seen previously. In the ductus deferens, cells had masses of long cilia with occasional microvilli; endoplasmic reticulum was well developed, forming complex arrays with sparse secretory droplets and basal mitochondria. In the seminal vesicle there were two cell types, the most common having long cilia and short microvilli and an occasional, paler cell with supranuclear accumulations of small, round mitochondria. These ultrastructural appearances have been related to cell glycosylation and functions including protein secretion, water absorption and waste removal, and illustrate how structure and function vary down the length of the genital tract.     

Peptide-immunoreactive nerves in the mammalian female genital tract

Summary Vasoactive intestinal polypeptide, substance P, neuropeptide Y and peptide histidine isoleucine immunoreactivities have been demonstrated in the female genitalia of rat, cat, mouse and guinea-pig using immunocytochemistry and radioimmunoassay. They were localized to nerves. Each type of immunoreactive nerve showed a distinct pattern of distribution, though all were associated to some degree with blood vessels and smooth muscle. Vasoactive intestinal polypeptide-immunoreactive and neuropeptide Y-immunoreactive nerves were the most abundant. Higher concentrations of peptides were detected in the female genitalia of the mouse than those of the other species studied. Vasoactive intestinal polypeptide-immunoreactive nerves were particularly concentrated in the cervix (89.1±17.2 pmol/g, mean±S.E.M.) and the uterus (57.4±14.8 pmol/g) of the mouse, while neuropeptide Y immunoreactivity was more abundant in the Fallopian tube of the mouse (31.6±11.8 pmol/g) and the vagina of the rat (38.6±4.8 pmol/g) than in other regions. Separate populations of ganglion cells in the paracervical ganglia were found to contain vasoactive intestinal polypeptide and neuropeptide Y immunoreactivities. Peptide histidine isoleucine-immunoreactive and vasoactive intestinal polypeptide-immunoreactive nerves were similarly distributed, but the former were much less frequent. Substance P-immunoreactive nerves were seen mainly beneath the epithelium of the vagina and were, in general, more numerous in the guinea-pig than in other species. The significance of these peptide-immunoreactive nerves in the female genital organ remains to be determined.Dr. Wang is on leave from The Institute of Acupuncture, The Academy of Chinese Traditional Medicine, Peking, China.     

Morphology and function of the copulatory system in freshwater crabs of the genus Potamon

To understand the reproductive processes of freshwater crabs of the genus Potamon, we examined the first and second gonopod and the gonoducts of the female by histological methods. The gonopods are highly modified compared to those of other brachyuran crabs. In particular, the second gonopod is unusually long and has a special morphology, ending in a long sclerotized tube. Suggestions for the function of both gonopods and their different parts are presented. Tubulation of the first and second gonopod is observed. Rosette glands, which are abundant in the subterminal joint of the first gonopod, are connected to the sperm channel by cuticular pores. In females, the chitinous parts of the inner vulva may prove to have a more constant morphology than the external flexible structures. J. Morphol. 239:157–166, 1999. © 1999 Wiley‐Liss, Inc.