Secretory and basal cells of the epithelium of the tubular glands in the male Mullerian gland of the caecilianUraeotyphlus narayani (Amphibia: Gymnophiona)

Caecilians are exceptional among the vertebrates in that males retain the Mullerian duct as a functional glandular structure. The Mullerian gland on each side is formed from a large number of tubular glands connecting to a central duct, which either connects to the urogenital duct or opens directly into the cloaca. The Mullerian gland is believed to secrete a substance to be added to the sperm during ejaculation. Thus, the Mullerian gland could function as a male accessory reproductive gland. Recently, we described the male Mullerian gland of Uraeotyphlus narayani using light and transmission electron microscopy (TEM) and histochemistry. The present TEM study reports that the secretory cells of both the tubular and basal portions of the tubular glands of the male Mullerian gland of this caecilian produce secretion granules in the same manner as do other glandular epithelial cells. The secretion granules are released in the form of structured granules into the lumen of the tubular glands, and such granules are traceable to the lumen of the central duct of the Mullerian gland. This is comparable to the situation prevailing in the epididymal epithelium of several reptiles. In the secretory cells of the basal portion of the tubular glands, mitochondria are intimately associated with fabrication of the secretion granules. The structural and functional organization of the epithelium of the basal portion of the tubular glands is complicated by the presence of basal cells. This study suggests the origin of the basal cells from peritubular tissue leukocytes. The study also indicates a role for the basal cells in acquiring secretion granules from the neighboring secretory cells and processing them into lipofuscin material in the context of regression of the Mullerian gland during the period of reproductive quiescence. In these respects the basal cells match those in the epithelial lining of the epididymis of amniotes.

Histology and ultrastructure of male mullerian gland of Uraeotyphlus narayani (Amphibia: Gymnophiona)

This study reports the anatomy, histology, and ultrastructure of the male Mullerian gland of the caecilian Uraeotyphlus narayani, based on dissections, light microscopic histological and histochemical preparations, and transmission electron microscopic observations. The posterior end of the Mullerian duct and the urinogenital duct of this caecilian join to form a common duct before opening into the cloaca. The boundary of the entire gland has a pleuroperitoneum, followed by smooth muscle fibers and connective tissue. The Mullerian gland is composed of numerous individual tubular glands separated from each other by connective tissue. Each gland has a duct, which joins the central Mullerian duct. The ducts of the tubular glands are also surrounded by abundant connective tissue. The tubular glands differ between the column and the base in regard to the outer boundary and the epithelial organization. The basement membrane of the column is so thick that amoeboid cells may not penetrate it, whereas that around the base of the gland is thin and appears to allow migration of amoeboid cells into and out of the basal aspect of the gland. The epithelium of the column has nonciliated secretory cells with basal nuclei and ciliated nonsecretory cells with apical nuclei. In the epithelium of the base there are secretory cells, ciliated cells, and amoeboid cells. The epithelium of ducts of the tubular glands is formed of ciliated dark cells and microvillated light cells. The epithelium of the central duct is formed of ciliated dark cells also possessing microvilli, ciliated light cells also possessing microvilli, and microvillated light cells that lack cilia. It is regressed during March to June when the testis lobes are in a state of quiescence. The Mullerian gland is active in secretion during July to February when the testis is active in spermatogenesis.

Region-specific inhibition of prostatic epithelial bud formation in the urogenital sinus of C57BL/6 mice exposed in utero to 2,3,7,8-tetrachlorodibenzo-p-dioxin

In utero 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure causes abnormal ventral, dorsolateral, and anterior prostate development in wild-type but not aryl hydrocarbon receptor (AhR) null mutant C57BL/6 mice. Experiments have now been conducted to test the hypothesis that TCDD causes an AhR-dependent inhibition of the earliest visible stage of prostate development, the formation of prostatic buds by urogenital sinus (UGS) epithelium. A novel method for viewing budding was developed that uses scanning electron microscopy of isolated UGS epithelium instead of three-dimensional reconstruction of serial histological sections of intact UGS. In the initial experiment, the time course for prostatic epithelial bud formation in vehicle- and TCDD-exposed wild-type C57BL/6J mice was determined. A single maternal dose of TCDD (5 mug/kg) on gestation day 13 delayed the appearance of dorsal, lateral, and anterior buds by about one day, reduced dorsolateral bud number, and prevented ventral buds from forming. No such effects were seen in TCDD-exposed AhR null mutant fetuses, while AhR null mutation, alone, had no detectable effect on budding. Treatment of wild-type dams with sufficient 5alpha-dihydrotestosterone (DHT) to masculinize female fetuses failed to protect against the inhibition of budding caused by TCDD. These results demonstrate that in utero TCDD exposure causes an AhR-dependent inhibition of prostatic epithelial bud formation commensurate with its inhibitory effects on ventral and dorsolateral prostate development, and that the inhibition of budding is not due to insufficient DHT. Inhibited bud formation appears to be the primary cause of abnormal prostate development in TCDD-exposed mice.

The genus Acipenser as a model for vertebrate urogenital development: the müllerian duct

The development of the müllerian duct was studied in a total of 85 specimens of Acipenser ruthenus and Acipenser baeri in the period from 7 days after hatching through 5 years of age. Normal histology on serial sections, transmission and scanning electron microscopy and bromodeoxyuridine immunohistochemistry were applied. In Acipenser, the primary set of opisthonephric nephrons possess short nephrostomial tubules with well-developed nephrostomes. Proliferating cells from the lateral side of the slightly protruding nephrostomial lips spread out over the ceolomic surface, replace here the flat mesothelium of lateral plate origin and establish the infundibular field, consisting of cuboidal or columnar cells. At about 28 days after hatching, the primordium of the müllerian infundibulum becomes visible in the form of a pocket-like invagination within the infundibular field. This invagination is found coexisting with and located laterally to the line of intact nephrostomes. The müllerian infundibulum, therefore, does not represent the homologon of a nephrostome itself, but must be regarded as a separate and secondary structure. The müllerian duct proper has its origin in cells from the bottom of the infundibular pocket. These cells grow as a tubule with a solid tip in the caudal direction, paralleling the wolffian duct, but without a contribution of cells from the latter. In Acipenser, a müllerian duct is present also in the adult male. In males as in females, the caudal extremity of the müllerian duct generally divides into two to three smaller terminals which end in the wolffian duct at different levels, but always cranial to the urogenital sinus. In most indifferent animals and in all males of this study, the tips of the müllerian terminals are closed and covered by a thin layer of wolffian epithelium. In adult females, the müllerian ducts end with open terminals. In both sexes, the adult müllerian duct is lined by a pseudostratified columnar epithelium, consisting of ciliated, non-ciliated and basal free cells.

Early development of the müllerian duct in avian embryos with reference to the human. An ultrastructural and immunohistochemical study

In vertebrates, the female reproductive system arises from the Müllerian (paramesonephric) duct which develops in both sexes under the influence of the Wolffian (mesonephric) duct. For a better understanding of the interactions between the Müllerian duct and its adjacent tissues, we present a systematic scanning and transmission electron microscopic investigation of early stages of avian Müllerian duct development. This starts within the cranial part of the Müllerian ridge from a placode-like thickening and deepening of the coelomic epithelium containing nephrostomes as remnants of the last pronephric and first mesonephric tubules. Groups of cells detach from this placode and rapidly expand caudally as a solid cord. This becomes canalized, but the tip region remains mesenchymal and is found enclosed within the basal lamina of the Wolffian duct. Immunostaining reveals that the Müllerian duct migrates within a matrix rich in laminin and entactin. When the canalized duct has opened into the coelomic cavity, one or more secondary ducts are found immediately caudal of the main funnel, for a short period only, possibly to supply material to the expanding duct. BrdU-anti-BrdU reaction reveals a high proliferation of the duct epithelium. The thickened epithelium of the Müllerian ridge dissolves to form the mesenchymal layers of the duct. Immunostaining with vimentin argues against a cellular contribution of Wolffian duct cells to the Müllerian duct. Comparing the data from avian embryos with those of human indicates that the modalities of early Müllerian duct development are similar in both species.

Tumor of the broad ligament in von Hippel-Lindau disease of probable mullerian origin

A rare neoplasm seen in women with von Hippel-Lindau disease is the papillary cystadenoma of the broad ligament, only three cases of which have been reported. All three exhibited characteristic histologic features identical to those of epididymal tumors that occur in affected patients, and were presumed to be of wolffian origin. This is the case of a broad ligament tumor in a woman with von Hippel-Lindau disease that had features more consistent with a mullerian rather than wolffian origin. This is the first report of a broad ligament tumor of probable mullerian origin in von Hippel-Lindau disease.

Ultrastructure of mullerian and wolffian ducts of fetal rabbit in vivo and in organ culture

Emphasis is put on programmed cell death in the epithelial cells of mullerian and wolffian ducts, in rabbit fetuses, by observations on the timing and ultrastructural characteristics of cell degeneration. Genital tracts were collected on days 17 to 25 post-coitum and processed for electron microscopy. An organ culture assay was performed on fetal ducts and testis or ovary, for 4 days. Then, ducts and gonads were processed for electron microscopy. The involution of male mullerian and female wolffian ducts in culture and in vivo follows a similar pattern. Cell degeneration is initialized by an increase in the number of lysosomes which are subsequently involved in invading autophagic vacuoles. Cytochemical localizations of acid phosphatase and aminopeptidase indicate the presence of new lysosomes within the cells. In conclusion, this cell degeneration seems to be due to a double lysosome system in the rabbit urogenital ridge: A mullerian one spontaneously inactive when mullerian inhibiting substance is absent, and a wolffian one, spontaneously active when testosterone is absent. The organ culture is reliable for further attempts to study the responses to substances known to act on lysosome formation or activity.

Immunocytochemical demonstration of the binding of growth-related polypeptide hormones on chick embryonic tissues

The presence of endogenous growth-related polypeptide hormones, such as growth hormone (GH), somatomadin-C/insulin-like growth factor-1 (SM-C/IGF-1), prolactin (PRL) and Mullerian inhibiting substance (MIS) on chick embryonic tissues have been detected by electron microscopic (EM) immunocytochemistry. Antiserum against GH, anti-SM-C/IGF-1, anti-PRL and anti-MIS were used respectively as primary antibodies for immunolabeling probes by peroxidase (PO) and avidin-biotin complex (ABC)-gold ligands. Cross-reaction studies by ELISA showed negative or weak antigen-antibody interactions. Chick embryos, gonads, and Mullerian ducts (Mds) of various ages were fixed in 2.5% glutaraldehyde for 30 min. Washes in phosphate buffer were administered between each of the following incubations: (i) 2% BSA; (ii) primary antibody; (iii) biotinylated or PO-conjugated secondary antibody; (iv) avidin conjugated with gold particles. SM-C/IGF-1 bindings were negative on 1d embryonic disc, heavily stained on 2d endoderm. However, the GH bindings were found on the embryonic layers of 1d and 2d embryos, and increasing on the luminal epithelial cells of Mds during development. PRL was found in parallel with GH, but in less amount. The 10d Mds were double labeled with anti-SM-C/IGF-1-gold and anti-MIS-PO (MIS-PO), and the results showed SM-C/IGF-I negative, but MIS-PO positive bindings. This study provides the first immunocytochemical evidences for: (i) The presence of GH, SM-C/IGF-1, PRL and MIS bindings on chick embryonic tissues, and further supports their potential role as growth mediators during embryonic development. (ii) The amount of GH and MIS bindings were found correspondingly to their physiological status of Md growth or regression.(ABSTRACT TRUNCATED AT 250 WORDS)

Epithelio-mesenchymal interface and fibronectin in the differentiation of the rat mesonephric and paramesonephric ducts

The distribution of fibronectin and the morphological differentiation of the genital ducts was studied in rat fetuses at ages from 15 to 21 days. Fibronectin was localized with the peroxidase-antiperoxidase and avidin-biotin method at the electron- and light-microscope level. In 15-day-old male and female fetuses, fibronectin was localized as a continuous lamella around the mesonephric duct and as a discontinuous lamella around the paramesonephric duct. During the differentiation of the female paramesonephric duct, the fibronectin layer became continuous and remained so after the age of 16 days. The fibronectin layer of the male mesonephric duct remained continuous at all ages. The accumulation of mesenchymal cells on the outer surface of the female mesonephric duct and the concomitant detachment of the fibronectin layer around the duct suggests that mesenchymal regulation plays a role in the regression of the mesonephric duct. In the regressing male paramesonephric duct fibronectin was simultaneously lost in the condensed periductal mesenchyme, the places of epithelio-mesenchymal contact, and the epithelial cytoplasmic protrusions towards the mesenchyme. Ultrastructurally, fibronectin was localized in the basal laminae, on the cell membrane in contact with the extracellular material, and on the surface of the fibrillar and flocculent extracellular material. In addition to auto- and heterophagy, epithelio-mesenchymal interactions seem to play an important role in the regression of the genital ducts, although in different ways in males and females. The present results give additional support to the theory of the possible migration of epithelial cells into the surrounding mesenchyme during the regression of the paramesonephric duct.

Contacts between Wolffian and Müllerian cells at the tip of the outgrowing Müllerian duct in rat embryos

The developing Müllerian duct was studied at the light microscopic as well as the electron microscopic level in rat embryos, especially in the section of the terminal bud and its tip, where Wolffian and Müllerian duct are enclosed by a common basal membrane. In this zone desmosomes can be found among Wolffian cells and also among Müllerian cells. In addition, we found cell contacts between Müllerian and Wolffian cells, namely short electron-dense segments on adjacent surfaces or disc-shaped thickenings within opposite plasma membranes, as well as fusions of the plasmalemmata over short distances. Until now, these cell contacts have not been described in rat embryos.

A comparative study of the differentiation and involution of the Mullerian duct and Wolffian duct in the male and female fetal mouse

The present investigation has examined the ultrastructural differentiation of the genital ducts of both sexes of fetal mice. The emphasis of observations was placed on the phenomenon of morphogenetic cytolysis, particularly during the critical periods of Wolffian duct stabilization and Mullerian duct involution. Both developing and regressing genital ducts evidence extensive cytolysis. Autophagy appears to be the mechanism of morphogenetic changes in the developing male Wolffian duct. Autophagy, heterophagy, and degeneration in situ are all prominent cytolytic activities in female Wollfian duct involution. The developing female Mullerian duct undergoes extensive morphogenetic remodeling by the mechanisms of autophagy, heterophagy, and degeneration in situ. In the male Mullerian duct, autophagy, heterophagy, and degeneration in situ are also prominent. In addition, whole degenerated epithelial cells are extruded from the duct early in regression which may be realted to the transformation of periductal mesenchymal cells into an "epithelioid cell cuff" which does not form around the regressing Wolffian duct. The formation of this mesenchymal condensation surrounding the duct is also accompanied by the protrusion of Mullerian epithelial cell cytoplasm into the mesenchymal cells. These observations may evidence a complex epithelial-mesenchymal interaction occurring during male Mullerian duct involution.

Programmed cell death in the Müllerian duct induced by Müllerian inhibiting substance

The importance of a secretory product of the fetal testis, Müllerian Inhibiting Substance, in determining the fate of the Müllerian duct in the developing male fetus has been well documented. The present investigation has examined the mechanism of action of Müllerian Inhibiting Substance in the male rat fetus during the course of Müllerian duct degeneration. The action of Müllerian Inhibiting Substance mimics the general morphogenetic phenomenon of "programmed cell death," although important diferences were found compared to the majority of other studies of cell death. The initial morphological event in the degenerating Müllerian duct is an increase in lysosomes within the duct cells. Following loss of polarity and orientation, the duct cells are subsequently removed by invading macrophages from the surrounding mesenchyme. Concommitant with the differentiation of these macrophages, the adjacent mesenchyme assumes a characteristic whorled pattern around the degenerating Müllerian duct. Cytochemical localization of acid phosphatase confirmed the presence of newly formed lysosomes within the Müllerian duct cells and subsequently within the cytoplasm of the invading macrophages.

Study on sex-organ development. Oestrogen-receptor translocation in the developing chick Müllerian duct

After oestradiol administration in vivo, 87-95% of the initial concentration of oestradiol receptor in the cytoplasm of the embryonic-chick Müllerian-duct cell was translocated into the nucleus. The process of translocation depends on the amount of oestardiol administered in vivo. At 6 h after oestradiol administration in vivo, about 30% replenishment of the initial content of the cytosol receptor was observed in the cytoplasm. The Müllerian-duct nuclei, after exposure to non-radioactive oestradiol, exhibit saturable exchange with [3H]oestradiol in vitro. The exchange of oestradiol is temperature- and time-dependent. The optimal temperature and time for exchange are 37-41 degrees C and 2h respectively. The [3H]oestradiol-receptor complex extracted from the exchanged nuclei is present in 5-6S form, and its isoelectric point is 6.8. The number of nuclear oestradiol-binding sites of the developing Müllerian duct are 1.66, 2.22, 2.63, and 2.50 pmol/mg of DNA respectively for embryos of 10, 12, 15 and 18 days. The dissociation constants of the nuclear oestradiol receptor of the four observed developmental stages range from 3.0 to 3.1 nM.

Testicular inhibition of fetal Mullerian ducts in vitro: effect of dibutyryl cyclic AMP

The effect of dibutyryl cyclic AMP (dibutyryl cAMP) on Mullerian ducts of 141/2-day-old rat fetuses in vitro was investigated. Dibutyryl cAMP was unable to produce the typical regression of Müllerian ducts which is observed in vivo in male fetuses and in vitro with Müllerian ducts in the presence of testes. Effects of dibutyryl cAMP and theophylline on regeneration of Müllerian ducts induced by fetal testes were also investigated, and it was found that 10(-3) dibutyryl cAMP added to the culture medium prevented the normal regression. Lower concentrations and theophyline (10(-3)M) were ineffective. An effect of lower doses of dibutyryl cAMP was obtained only when theophylline was also present. Because pretreatment of testes with dibutyryl cAMP did not prevent the inhibiting action of testes on Müllerian ducts, it is concluded that an interaction between dibutyryl cAMP and the inhibiting factor at the level of the target organs must be considered.