Morphology of the epididymis of the cock (Gallus domesticus) and its effect upon the steroid sex hormone synthesis. I. Ontogenesis, morphology and distribution of the epididymis.

The epididymis of the cock is divided into a main part and an appendix epididymidis. The main part of the epididymis is firmly connected to the testis. The sperm transporting tubes open into the ductus epididymidis along its entire length. The rete testis, as the most proximal part of the epididymis, develops from mesenchym cells. The rete testis connects the tubuli seminiferi with the ductuli efferentes proximales which develop from the Bowman's capsules of the mesonephros. The ductuli efferentes distales develop from the proximal tubules, conducting segments (loops of Henle), and the distal tubules of the mesonephros. The short ductuli conjugentes which open into the ductus epididymidis, originate from the connecting segments of the mesonephros. In the sexually mature cock the rete testis, the ductuli efferentes proximales, and the ductus epididymidis all show an enlargement in the lumen. In the ductuli efferentes proximales and in the ductus epididymidis one can observe a formation of globuli and cell protrusion which lead to a loss of the surface structure of the epithelial cells. The appendix epididymidis and the capsula fibrosa of the adrenal gland are joined by connective tissue. The appendix epididymidis consists of the blindly ending ductus aberrans (the crainal continuation of the ductus epididymidis) and the ductuli aberrantes which open into the ductus aberrans. The blind ends of the ductuli aberrantes end in the capsula fibrosa of the adrenal gland.     

On the origin and prenatal development of the bovine adrenal gland

Decisive steps of bovine prenatal adrenal development were investigated in 46 embryos and fetuses using histological, electron microscopical, immuno-, enzyme and lectin histochemical methods. About day 30, the intermediate mesoderm between the cranial mesonephros and coelomic cavity is segmentally organized. It consists of proliferating tissue complexes that are connected to the coelomic cavity by vestigial nephrostomial tubules. This segmental organization soon disappears, however, due to longitudinal fusion of the tissue complexes into a continuous joined blastema. This blastema of intermediate mesodermal (nephric) origin becomes positive for alkaline phosphatase at about 30 days, and slightly later also for acetylcholinesterase. The most cranial portions of this common blastema represent the adrenocortical anlage, the following portions the gonadal rete blastema. A reevaluation of the comparative anatomical record revealed that a nephric origin of adrenocortical or interrenal cells is a general feature of all vertebrates and that the erroneous assumption of the lateral plate-derived coelothelium as precursor of the adrenocortical (interrenal) blastema should be definitively abandoned. The first adrenomedullary precursor cells become visible in the bovine adrenal primordium at day 35. At 50 days, both components (medullary and cortical precursors) are present as interpenetrating plates and strands between large sinusoid vessels and exhibit a strong MIB-1 activity, indicative of a high proliferation rate. About day 60 the cellular proliferation slows down in some of the adrenocortical precursor cells, and the separation into a visible cortex and medulla is initiated. From about day 80 on, the medullary tissue coalesces into a large, continuous area in the interior of the gland, surrounded by a narrow cortical glomerulo-fasciculata that becomes positive for 3beta-hydroxysteroid dehydrogenase at about day 90. Autonomous nerves penetrate the blastemal region as early as day 31. When the separation into cortex and medulla starts, the nerves are more concentrated in the latter. From 130 days on, nerve fascicles reach the interior of the organ not only from its medial side, but also from the capsule surrounding the gland. The penetrating bundles traverse the zona glomerulo-fasciculata without ramification and split off at the border to the medulla. Here, in the outer zone of the medulla, they constitute a particularly dense plexus, whereas in the central medulla a less dense innervation is observed. Up until 90 days, cells with the characteristic features of primordial germ cells are present within the confines of the adrenal gland.     

Development of the early human ovary and role of the mesonephros in the differentiation of the cortex

Summary The morphogenesis of the primary gonadal differentiation, of the sexual differentiation and the growth of the ovarian cortex during its early period have been studied on 10 human embryos between 12 and 95 mm CR-length. Semithin sections of glutaraldehyde-OsO₄-fixed and plastic-embedded material were used to demonstrate the structural events on a cellular level. The primary gonadal blastema within the genital ridge is formed by two types of somatic cells: cells segregated from the mesonephros and cells of the proliferating coelomic epithelium. The two types of cells show a tendency to intermingle and they enclose the immigrating primordial germ cells. In the female gonad the indifferent period terminates between day 40 and 42 of ovulation age (20 to 23 mm CR-length). Between day 40 and 50 the blastemal content of the indifferent gonad is remodelled and an ovarian cortex differentiates. Cellular strands extending from the primary blastema and strands from the superficial blastemal layer contribute to the formation of the cortex. Within the newly formed medulla, remnants of the disintegrating primary blastema differentiate into medullary cords.Cells of mesonephric origin which invade the growing cortex via the rete blastema interact with cells deriving from the supericial epithelium, and both exert their opposite influence on the germ cells. While female sexual differentiation is characterized by failure of the dark mesonephric cells to completely penetrate the gonadal blastema, the morphogenetic process resulting in the formation of the ovarian cortex shows a strong invasion of the cortex by the dark mesonephric cells. Dark cells advance at the most superficial layer of the cortex and increase in number at the deeper level of the cortex. Onset of oogonial proliferation and meiotic prophase seems to depend on the numerical proportion between the activating dark and the inhibiting light supporting cells.Supported by the Deutsche Forschungsgemeinschaft     

Distribution and regulation of progesterone receptor in the urogenital tract of the chick embryo

Summary The early appearance, cellular distribution, and hormonal regulation of the progesterone receptor was studied in the urogenital tract of the chick embryo using antibodies to the receptor molecule. In embryos at day 5 of incubation the receptor is revealed in cell nuclei of the mesenchyme and the coelomic epithelium near the primordium of the urogenital sinus. In embryos at days 6 to 10 immunostained cells are found in the mesenchyme surrounding the urodeal and proctodeal epithelia. The first difference between male and female embryos appears at day 8, with a higher density of progesterone receptor-containing cells along the urogenital sinus epithelium in females. The female type of receptorpositive cell distribution can be induced in males by oestradiol treatment. Anti-oestrogens applied from day 0 of incubation do not prevent or delay the appearance of PR, but induce a male-type distribution in female embryos. In the gonads, immunostained cells appear unambiguously at day 6 in the medulla. At later stages, the receptor is revealed mostly in the medulla, although there are also positive cells in the cortex of the left ovary. The immunoreactivity is not significantly modified by oestradiol or anti-oestrogens. The mesonephros is devoid of immunoreactivity, whereas most cells of the metanephric mesenchyme are receptor-positive. In the Mullerian ducts progesterone receptor is not detected in control embryos of either sex until after day 10. Between days 6 and 7 Mullerian ducts become responsive to oestradiol, which induces progesterone receptor in luminal epithelial cells. In the spinal cord, receptor is detected in neurones of the ventral horn and the meninges, starting at day 6. The progesterone receptor is up-regulated by oestradiol in the mesenchymal cells, Mullerian ducts, and mesothelium, but not in the gonads or the spinal cord. In none of the tissues or organs where the receptor appears naturally during development could an anti-oestrogen treatment with Tamoxifen or RU39411 block or delay its constitutive appearance. The widespread and specific distribution of the progesterone receptor, its programmed appearance in various organs, and its precise hormonal regulation, are in favour of a morphogenetic role of progesterone in tissue differentiation, related or not to sexual differentiation of the urogenital tract.     

Histogenesis and organogenesis of the gonads in human embryos

The histogenesis and organogenesis of the human gonad in twelve embryos and six fetuses of ovulational ages 5 to 18 weeks was investigated by histological and ultrastructural examination, including observation of almost complete serial Epon-embedded sections of the entire gonads of 10 embryos. This investigation revealed that the main constituent cells of the gonads are derived from the mesonephros, and that the coelomic epithelium is not involved in the formation of the main component at any stage.     

Involution and regeneration of the thymus in mice,induced by bacterial endotoxin and studied by quantitative histology and electron microscopy

Lipopolysaccharide from S. typhosa, injected intraperitoneally into Swiss albino mice, produced acute thymic involution—maximal at 48 hours after injection, followed by regeneration that was complete within 5 to 7 days. Using tissues fixed and embedded for electron microscopy, cell counts were made with the light microscope and cytological details were examined in electron micrographs. The cellular events of involution and regeneration were similar to those produced by injection of adrenal glucocorticoids, but it remains to be determined whether or not endotoxin acts on the thymus by inciting adrenal cortical secretion. Involution appeared to be the result of both the death of small lymphocytes and reduced lymphopoiesis in the thymus. Within 48 hours, macrophages had cleared away the cellular debris and medullary epithelial cells showed signs of hypertrophy and increased putative secretory activity. Subsequently, large lymphocytes proliferated at an accelerated rate in the subcapsular cortex, the cortex grew in width by the accumulation of small lymphocytes, and regeneration ceased when the thymus had reached its former size. These observations provide circumstantial evidence for the hypothesis that in regeneration, medullary epithelial cells increase their production of a lymphopoietic hormone which stimulates mitotic proliferaton of cortical lymphocytes.     

Mesonephric excretory function related to its influence on differentiation of fetal gonads

The mammalian intermediate fetal kidney, the mesonephros, is known in different species to excrete body waste products during a limited period of fetal life. Recently, the mesonephros and its derivatives have been shown to influence gonadal functions in several ways. Thus, the mesonephric cells are responsible for regulating the onset of meiosis in different mammals by the secretion of two substances, a meiosis-inducing substance (MIS) and a meiosis-preventing substance (MPS). In this paper, the relation between mesonephric kidney function and its influence on the gonads is reviewed through literature studies. It seems that cessation of mesonephric excretion precedes onset of meiosis in the ovary in different species. It is suggested that the mesonephric renal function interferes with synthesis and/or secretion of MIS or that the excreted products may interfere with the responsiveness to MIS of the germ cells.     

The contribution of the mesonephros to the development of the sheep fetal testis

In this study, which was performed on 52 sheep fetuses aged 24 to 85 days, we examined the relationship between testicular development and the “giant” mesonephric nephron, a peculiar structure consisting of a large glomerulus and multiple tubules. The development of the testis occurred in two phases. The preparatory phase began at day 24 of gestation, evolved simultaneously with the involution of the glomerulus of the giant nephron, and was characterized by mobilization of the glomerular cells and by their colonization of the genital ridge. By day 31, a prominent mass of migrating mesonephric cells had developed; it extended uninterrupted from the giant glomerulus into the gonad where the mesonephric cells associated with the germinal cells forming the cellular template from which the testicular cords later became assembled. At complete involution of the glomerulus (day 52), the migratory mass implanted on the tubules of the giant nephron, which thus became continuous with the gonad. During the organizational phase, which began at day 29 with the formation of the tunica albuginea, the various components of this continuum became progressively organized along a testis-to-mesonephros direction into seminiferous cords, tubuli recti, the cords of the rete testis, and the ductules efferentes. These observations show that, in the sheep, the precursors of the Sertoli cells are mesonephric in origin, and that the genital tract proximal to the epididymis differentiates from a single mesonephric nephron.     

Mature oocytes derived from purified mouse fetal germ cells

BACKGROUND: Mouse fetal germ cells have been successfully purified from fetal gonads. However, there are no published reports describing a procedure for deriving mature oocytes from isolated fetal germ cells. The purpose of this present study is to explore whether purified fetal germ cells are able to differentiate into mature oocytes through an in vivo grafting procedure. METHODS AND RESULTS: First, intact 11.5 and 12.5 days post-coitum (dpc) female gonads with or without the attached mesonephros and the reaggregated female gonad cells were transplanted into the recipient mice. The results demonstrate both the gonad accompanied by mesonephroi and the innate gonad structure are not absolutely required for 11.5 dpc and 12.5 dpc oogonia to generate mature oocytes. Next, oogonia were purified from female gonads, aggregated with different ovarian somatic cells and transplanted into the recipient mice. Purified 12.5 dpc oogonia were able to generate mature oocytes by aggregating with 12.5 dpc ovarian somatic cells, but not with 16.5 dpc or 0 days postpartum ovarian somatic cells. We also tested 12.5 dpc male germ cells but they were unable to undergo oogenesis. CONCLUSIONS: Our study demonstrates that mature oocytes can be derived from purified fetal germ cells through an aggregation and transplantation procedure. It also suggests that the synchronized interactions between oogonia and gonadal somatic cells are important to ensure normal folliculogenesis.     

Development of adrenal chromaffin tissue

The purpose of the present investigation was to study the morphological peculiarities of chromaffinoblasts and to determine their interrelations with the surrounding cellular elements of the fetal cortex at the early stages (embryonic weeks 4-7) of their migration into the developing adrenal gland of a pig. At week 5 neuro-cellular cords, consisting of so-called "naked" axons, neuroblasts, lemmoblasts, undifferentiated cells, chromaffinoblast clusters and chromaffinocytes, grow into the fetal cortex from side of abdominal aorta. In fetal cortex parenchyma chromaffin elements form cords, lobes, "medullary globes", which are enveloped by a basal membrane, which is a derivative of satellitocytes. Chromaffinocytes are stained with Wood's stain, potassium bichromate and, judging by the presence of secretory granules in their cytoplasm, are capable to synthesize summary catecholamines and to release them into the blood at the early stages of development. "Medullary globes" are the centers of proliferation and differentiation of the chromaffin cells in the adrenal medulla. The problem of chromaffin tissue stem cells is discussed.     

The further characterization of autoantibodies reactive with extra-adrenal steroid-producing cells in patients with adrenal disorders

Antibodies reactive with the steroid-producing cells in the gonads are described in the sera of ten patients, the majority of whom were known to have idiopathic adrenal insufficiency (Addison's disease) associated with premature ovarian failure. The immunofluorescent staining pattern of these antibodies with steroid-producing cells in the ovary, testis, placenta and adrenal cortex are illustrated. The staining patterns and the results of absorption studies indicate that there are a multiplicity of antibodies reacting with different antigens in the ovary and to a lesser extent in the testis. Most of these antigens are also represented in the adrenal cortex, but are not evenly distributed throughout the cortex. Some of these antigens are not represented in the zona glomerulosa while others are not represented in the zona reticularis.     

The development of the caudal ligaments of the mesonephros and of the gonads: a contribution to the development of the human gubernaculum (Hunteri)

The formation of the two caudal mesonephric folds is described. The plica uropelvina becomes the plica urogenitalis as soon as the paramesonephric (Müllerian) duct grows, and the plica inguinalis runs over the ridge of the umbilical artery to the ventral abdominal wall. Within the plica inguinalis the inguinal or caudal mesonephric ligament is formed directly subjacent to the coelomic epithelium. It interacts intensively with the mesenchyme sheath of the paramesonephric (Müllerian) duct in stage 21. It is separated by loose mesenchyme from the subjacent mesonephros and mesonephric (Wolffian) duct which therefore it does not pass beneath. In stage 23, and during the early fetal period, the caudal gonadal ligament is formed. It arises from the caudal pole of the gonads and proliferates in the space between the two genital ducts. Only the duct not destined to disappear associates with it. Therefore, in males the gubernaculum consists of the inguinal ligament of the mesonephros only. Its significance for the descent of the testis is discussed. In females the inguinal and the caudal gonadal ligaments fuse into a single strand and together form the gubernaculum.     

Formation of the chick mesonephros

Summary The post-induction pattern of nephron organization was analysed by microdissection of 6- and 8-day chick embryo mesonephroi marked in two transversal planes by a standard technique allowing the exact determination of homologous portions. It was proved possible to distinguish four nephron populations with Malpighian corpuscles situated on the surface of the kidney, which were arranged in a ventrodorsal sequence according to age. These populations formed practically two thirds of the mesonephros. A fifth (the youngest and very heterogenous) population was localized deep in the mesonephros forming most of the dorsal half of the organ. The correct determination of the sequence of the nephron populations according to their origin was verified by the corresponding gradient of the lengths of their tubules. The oldest population (V1) constituting a ventral surface of mesonephros was the largest; it comprized in average 29±1 nephrons and stretched from the cranial to the caudal pole. The cranial narrower part of the mesonephros (crp) was composed exclusively of the V1 nephrons. The other nephron populations occurred only in the caudal, growing part of the mesonephros. The total number of nephrons per mesonephros was close to one hundred (97±7). In all isolated nephrons, the glomerulus was found to be firmly connected to the intermediate segment of the tubule at the site of the second main flexure. Developmental irregularities, as rudimentary or hypertrophic nephrons occured in crp only, but the abnormality known as two-headed nephron was distributed more or less at random in the mesonephros with the mean frequency 6.5% of the isolated nephrons.     

Gene transfer by electroporation into hemogenic endothelium in the avian embryo

Hematopoiesis is the dynamic process whereby blood cells are continuously produced in an organism. Blood cell production is sustained by a population of self‐renewing multipotent hematopoietic stem cells (HSCs) throughout the life of an organism. Cells with definitive HSC properties appear in the mid‐gestation embryo as dense clusters of cells budding from the floor of the aorta, and that of the vitelline and umbilical arteries in the aorta‐gonads‐mesonephros region. Attempts to genetically modify the aortic floor from which these HSCs arise have been unsuccessful in the mouse, since the regulation of gene expression in the hemogenic endothelium is largely unknown. Here we report the implementation of gene transfer by electroporation into dorsal aortic endothelial cells in the chick embryo. This approach provides a quick and reproducible method of generating gain/loss‐of‐function models to investigate the function of genes involved in HSC birth. Developmental Dynamics 239:1748–1754, 2010. © 2010 Wiley‐Liss, Inc.     

Desert Hedgehog/Patched 1 signaling specifies fetal Leydig cell fate in testis organogenesis

Establishment of the steroid-producing Leydig cell lineage is an event downstream of Sry that is critical for masculinization of mammalian embryos. Neither the origin of fetal Leydig cell precursors nor the signaling pathway that specifies the Leydig cell lineage is known. Based on the sex-specific expression patterns of Desert Hedgehog (Dhh) and its receptor Patched 1 (Ptch1) in XY gonads, we investigated the potential role of DHH/PTCH1 signaling in the origin and specification of fetal Leydig cells. Analysis of Dhh(-/-) XY gonads revealed that differentiation of fetal Leydig cells was severely defective. Defects in Leydig cell differentiation in Dhh(-/-) XY gonads did not result from failure of cell migration from the mesonephros, thought to be a possible source of Leydig cell precursors. Nor did DHH/PTCH1 signaling appear to be involved in the proliferation or survival of fetal Leydig precursors in the interstitium of the XY gonad. Instead, our results suggest that DHH/PTCH1 signaling triggers Leydig cell differentiation by up-regulating Steroidogenic Factor 1 and P450 Side Chain Cleavage enzyme expression in Ptch1-expressing precursor cells located outside testis cords.     

Expression of the human NOV gene in first trimester fetal tissues

NOV, located on human chromosome 8q24.1, was originally cloned following discovery of its avian homolog as a consequence of over-expression in virally induced nephroblastoma. The gene product is a secreted, modular, protein and a member of the CCN gene family. Evidence to date indicates that the expression of the wild type protein is associated with cellular quiescence in normal embryonic fibroblasts yet produces growth stimulatory effects on established murine NIH 3T3 cells. Here we report the expression of NOV in the first trimester of human embryogenesis, between 5 and 10 weeks. In situ hybridisation and immunohistochemistry reveal widespread expression in derivatives of all three germ layers. The most abundant sites of expression are in the motor neurons and floor plate of the spinal cord, adrenal cortex, fusing skeletal, and smooth muscle, the urogenital system and the developing heart. Additionally, expression is seen in the cranial ganglia, differentiating chondrocytes, gonads, and lung. The sites of expression suggest strongly that autocrine or paracrine expression of NOV is associated with the process of cell differentiation.     

Fine structure and morphogenesis of spironolactone bodies in the zona glomerulosa of the human adrenal cortex

Numerous spironolactone bodies have been detected in the zona glomerulosa cells of the adrenal cortex of a 36-year-old spironolactone-treated woman whose non-tumorous right adrenal gland was removed surgically because of primary hyperaldosteronism. Electron microscopy revealed spherical laminated whorls which consisted of a central core composed of an amorphous electron-dense material surrounded by numerous smooth-walled concentric membranes. Continuous with and deriving from the endoplasmic reticulum, they were present in viable cells and were not associated with ultrastructural features indicating cellular injury. Cytoplasmic inclusions similar to spironolactone bodies can be detected in other organs after the administration of various compounds. Thus, they can be regarded as neither specific to spironolactone treatment nor exclusively inducible in the zona glomerulosa of the adrenal cortex.     

Interrenal cell zonation in the adrenal gland of the goose (Anser anser)

The adrenal medulla in mammalian species is surrounded by a cortex that contains three distinct layers, whereas the cortex and medulla are intermingled in poultry species. The objective of the present study was to determine the distinct zonation changes in the adrenal cortex of geese in various ages using both electron and light microscopy. Adrenal glands were obtained from French Geese (Anser anser) under deep ether anesthesia at posthach day 1, 5, 10, 21 and 30 (n= 5 per day). The cytoplasm of interrenal cells located beneath the adrenal capsule (sub-capsular zone, SCZ) were stained lighter than that of interrenal cells located inside the adrenal gland (inner zone, IZ) and contained several vacuoles for each sampling day. Additionally, unlike IZ cells, SCZ cells contained nuclei that were various shapes and surrounded by irregularly arranged membranes, lipid droplets which were not surrounded by a membrane, mitochondria with mostly shelf-like cristae. The arrangement of SCZ cells appears similar to that of zona glomerulosa and also the arrangement of IZ cells to that of zona fasciculata of mammalian adrenal cortex, suggesting the significant signs of zonation in goose adrenal cortex.