Embryonic cholinesterase in the chick limb bud.
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Animals↗
Biomedical subjects
U Drews
Publications and source records attributed to U Drews.
The vagina is formed by downgrowth of Wolffian and Müllerian ducts. Graphical reconstructions from normal and Tfm mouse embryos.
We use the Tfm (testicular feminization) mutation of the mouse to reexamine the role of Wolffian and Müllerian ducts during formation of the vagina. Three dimensional graphical reconstructions of the lower genital tract are prepared from serial sections of male, female, and Tfm embryos from day 15 p.c. until 8 days after birth. The reconstructions show that in female and Tfm animals the caudal segments of Wolffian and Müllerian ducts fuse and migrate caudally, whereas in the male they do not fuse and remain in their original position. Following down-growth, separate Wolffian and Müllerian ducts emerge from the fused caudal tips of the ducts. The Wolffian ducts degenerate, while the Müllerian ducts fuse with each other and form the vagina. Wolffian and Müllerian ducts are connected to the urogenital sinus by the sinus ridges which in later stages are separated from the sinus by lateral furrows. The sinus ridges are replaced by the Müllerian ducts. We conclude that the vagina develops by down-growth of Wolffian and Müllerian ducts along the sinus ridges. Wolffian ducts and sinus ridges regress so that the definitive vagina is formed by the Müllerian ducts. In Tfm embryos the vagina forms as in the female but subsequently degenerates, probably due to the action of AMH. The vaginal pocket in the Tfm is the variable remainder of the vagina at the end of the degeneration process.
Animals↗
Ultrastructural localization of cholinesterase during chondrogenesis and myogenesis in the chick limb bud.
Cholinesterase (ChE) is transiently expressed in undifferentiated embryonic cells. In the chick limb bud ChE-activity was found in the apical ectodermal ridge and in the subridge mesenchyme. The reaction was localized in the perinuclear cisterna, in an extensive network of narrow profiles of endoplasmic reticulum (ER), and in the Golgi complex. The chondroblasts emerging from the subridge mesenchyme, also showed strong ChE-activity. During differentiation the enzyme first disappeared from the Golgi zone. Then, the narrow ChE-positive ER was successively replaced by ChE-negative extended rough ER characteristic for the differentiated chondrocyte. The myoblasts showed weak ChE-activity with the same ultrastructural localization as in other mesenchymal cells. After fusion the myotubes exhibited strong ChE-activity in the perinuclear cisterna and the developing sarcoplasmic reticulum. In later stages of myogenesis the myoblasts were closely attached to the myotubes and had lost their ChE-activity. During mitosis of ChE-positive cells, ChE-activity was retained in fragments of perinuclear cisterna and ER. In ChE-active mesenchymal cells and chondroblasts we observed specialized contact zones between ER and plasma membrane. ChE-active cisternae of ER run parallel to the plasma membrane with a gap of approximately 10-15 nm. We discuss a possible function of a cholinergic system during morphogenesis.
Animals↗
Differential distribution of 3H dihydrotestosterone and 3H estradiol nuclear binding sites in mouse male accessory sex organs. An autoradiographic study.
The distribution of specific nuclear binding sites for androgens and estrogens in the male accessory sex organs of the mouse was assessed by autoradiography with 3H dihydrotestosterone (3H DHT) and 3H estradiol (3H E2). With 3H DHT nuclear labeling differed among the epithelia of the organs. It was high in seminal vesicle and ampullary gland, moderate in ventral prostate, urethral gland, prostatic excretory ducts and the ampulla ductus deferentis, low in dorsal prostate and low or absent in coagulation gland. With 3H E2, in contrast, epithelial nuclear labeling was high only in coagulation gland, moderate or low in seminal vesicle, low or absent in ventral and dorsal prostate and absent in ampullary gland and ampulla ductus deferentis. In the lamina propria of all organs nuclear labeling with 3H DHT was generally moderate and existed only in some cells, with the highest number in the ampulla ductus deferentis. With 3H E2, nuclear labeling in the lamina propria showed a high intensity in all organs, except in ventral and dorsal prostate which remained unlabeled. Many labeled cells were found in the deferent duct and its ampulla, while in the other organs only a few cells showed nuclear labeling with 3H E2. In the smooth muscle sheath of all organs, some muscle cells were moderately labeled with 3H DHT, but not with 3H E2. The results indicate the presence of nuclear receptors in male accessory sex organs for both dihydrotestosterone and estradiol. The differential patterns of 3H DHT and 3H E2 nuclear uptake suggest differential sensitivities of the individual organs and their tissue compartments for androgens and estrogens.
Animals↗
The muscarinic receptor of chick embryo cells: correlation between ligand binding and calcium mobilization.
In this report we characterize muscarinic cholinergic receptor on embryonic cells. We established dose-response curves by fluorometric measurement of Ca2+ mobilization in cell suspensions of whole chick embryos stage 23/24. Ca2+ mobilization was quantitated by standardization of chlorotetracycline (CTC) fluorescence changes after stimulation with muscarinic agonists. We determined ED50 values for the agonists acetylcholine and carbachol as 3.4 X 10(-6) and 2.7 X 10(-5) M, respectively. Pilocarpine and oxotremorine were found to act as reversible competitive antagonists with inhibition constants (Kl) of 5.0 X 10(-6) and 1.4 X 10(-6) M, respectively. Bethanechol, which induced only 23% of the maximal effect obtained by acetylcholine, was a partial agonist with an ED50 of 4.8 X 10(-4) M. Its antagonistic component is expressed by an inhibition constant of 1.9 X 10(-4) M. In parallel, binding studies were performed in a competition assay with [3H]-quinuclidinylbenzilate. For the agonists acetylcholine and carbachol, binding parameters were best fitted by a "two binding-sites model." Comparison with dose-response curves indicated that Ca2+ mobilization was triggered via the high-affinity binding site. The inhibition constants of antagonists derived from the shift of dose-response curves corresponded to the fitted KD values of the binding studies when a "one binding-site model" was applied. Combination of dose-response and binding data showed close proportionality between receptor occupancy and calcium mobilization. No spare receptors were present.
Acetylcholine↗
Autoradiographic binding studies with [3H]oestradiol and [3H]dihydrotestosterone in the autonomic genital ganglion (plexus of Frankenhäuser) of the mouse.
Male, female and Tfm mice (testicular feminization) were injected with [3H]oestradiol or [3H]dihydrotestosterone, and autoradiograms prepared of male accessory sex organs and of the cervico-vaginal portion of the female reproductive tract. After injection of [3H]oestradiol in male, female and Tfm animals a nuclear concentration of radioactivity was found in a subpopulation--about 20-30%--of the neurons of the genital ganglion. No such concentration was seen after [3H]dihydrotestosterone. The results suggest a direct genomic effect of oestradiol on certain neurons of the autonomic genital ganglion in both sexes.
Androgen-Insensitivity Syndrome↗
Differential distribution of dihydrotestosterone and estradiol binding sites in the epididymis of the mouse. An autoradiographic study.
The distribution of androgen and estrogen binding sites in the mouse epididymis was assessed by autoradiography with 3H dihydrotestosterone (3H DHT) and 3H estradiol (3H E2). Nuclear labeling with 3H DHT in principal cells of the epithelium is high in the caput, low in the corpus, and high again in the cauda. 3H E2 also binds to the nuclei of principal cells. The pattern is distinct from 3H DHT: nuclear labeling is highest in the ductulus efferens and high in the caput, but low or absent in corpus and cauda. Apical cells in caput and clear cells in corpus and cauda are moderately labeled with 3H DHT but heavily labeled with 3H E2. Connective tissue cells show variable labeling with both hormones, being more pronounced with 3H E2. Smooth muscle cells are also labeled to varying degrees with both hormones. The different binding patterns of 3H DHT and 3H E2 and the results of the competition studies with unlabeled compounds demonstrate that in the epididymis besides the specific nuclear receptors for androgen also estrogen receptors are present.
Animals↗
Choline acetyltransferase in the chick limb bud.
In embryonic tissues a primitive cholinergic system is transiently expressed during morphogenesis. In the chick limb bud expression of the primitive cholinergic system in mesenchyme and central chondrogenic core precedes the appearance of the definitive cholinergic system in nerve and muscle. Here we show that, parallel to the expression of cholinesterase in mesenchyme and chondroblasts, embryonic cells are capable of acetylcholine synthesis. Choline acetyltransferase (ChAT) activity was measured by the radiometric assay of Fonnum (1975).
Animals↗
The role of the Wolffian ducts in the formation of the sinus vagina: an organ culture study.
In mammals formation of a sinus vagina is inhibited in the male by endogenous testosterone from the embryonic testes. To answer the question which morphogenetic events during formation of the vagina are influenced by testosterone, we explanted genital tracts of mouse embryos in the indifferent stage of development in organ culture. Half of the explants were treated with testosterone and therefore developed in male direction. The other half was kept without testosterone and developed constitutively in female direction. Since the anti Müller factor was not present, in both types of cultures the Müllerian ducts were preserved. During female development the Müllerian ducts fused with the dorsolaterally apposed caudal segments of the Wolffian ducts. Thus the caudal segments of the Wolffian ducts were incorporated in the vaginal plate, while cranially the Wolffian ducts degenerated as expected. During male development fusion between Müllerian and Wolffian ducts did not occur. Under the influence of testosterone the respective caudal segments of the Wolffian ducts were surrounded by dense mesenchyme and further male differentiation took place. We conclude that the 'sinus protrusions' or 'sinovaginal bulbs' observed during development of the vagina, are in fact the caudal segments of the Wolffian ducts. They serve as a link between Müllerian ducts and urogenital sinus. Formation of a sinus vagina is prevented by testosterone simply by induction of male development in this area.
Animals↗
[Prenatal development of cerebral veins and sinuses with variants and dysplasias].
A review is given on the development of the cerebral veins and sinuses in man illustrated by schematic drawings and phlebograms of comparable embryos and fetuses of higher vertebrates. The system of venous sinuses arises early in development from three dural plexuses and the primary head sinus according to a constant pattern. The internal cerebral veins and particularly the temporo-basal veins arise at a later stage from longitudinal anastomoses of ventral segmental veins of the pial venous plexus of the brainstem. Accordingly they exhibit a high degree of variability in the adult.
Brain↗
Stimulation of growth by testosterone via the mesenchyme. Recombination of tissues from Tfm and wild-type preputial gland anlagen of mouse embryo.
To establish testosterone-dependent growth in organ-culture anlagen of preputial glands from normal wild-type and from androgen-insensitive mouse embryos carrying the testicular feminization mutation (Tfm) were explanted and cultured in the presence of testosterone. Within six days a size difference developed between Tfm and wild-type explants involving length of hair follicle, amount of preputial gland tissue, and overall size. Anlagen from Tfm and wild-type preputial glands were then separated into epithelial bud and mesenchyme. Reciprocal recombinants were prepared and cultured with testosterone. In the recombinants development of hair follicles and gland tissue was inconsistent. Nevertheless, the effect of testosterone was expressed in the overall size of the explants. The size correlated with the type of mesenchyme used, but not with the type of epithelium: Androgen-insensitive Tfm epithelium combined with wild-type mesenchyme reached the same size as whole wild-type glands and wild-type/wild-type recombinants. Wild-type epithelium with Tfm mesenchyme resulted in small explants, which were in the range of the whole androgen-insensitive Tfm glands. Tfm/Tfm recombinants showed very poor growth, probably related to the fact that in this group no hair or gland structures developed.
Androgen-Insensitivity Syndrome↗
Intact testosterone receptor complex does not induce RNA synthesis of Tfm-nuclei in multinucleated urethral muscle fibres of mosaic mice.
The X-linked testicular feminization mutation (Tfm) of the mouse leads to androgen insensitivity of target cells. Through the autosomal sex reversed (Sxr) factor we have converted female heterozygotes into males. Due to X-inactivation, mosaic animals arise which are composed of androgen sensitive wild-type and androgen insensitive Tfm cells. In the androgen dependent striated urethral muscle, Tfm and wild-type cells fuse and form multinucleated muscle fibres. In the muscle fibres the Tfm nuclei are exposed to the intact cytoplasmic testosterone receptor complex coded for by the wild-type nuclei. We ask the question whether under these conditions RNA synthesis can be stimulated in the Tfm nuclei. Castrated mosaic animals were injected with testosterone, and incorporation of 3H-uridine was studied by autoradiography. We found two classes of muscle cell nuclei, those with low grain counts corresponding to the Tfm controls and those with high grain counts corresponding to the stimulated male controls. The results indicate that the Tfm nuclei are not stimulated by the intact testosterone receptor complex.
Animals↗
[Sex determination and sex differentiation].
Sex determination in mammals proceeds like a cascade from the level of the sex chromosomes to the gonads, to the genital ducts, and finally to the expression of the male or female phenotype. At the level of the genital ducts male sex organs are induced by testosterone. Its action depends on an intact cytoplasmic androgen receptor protein. The testicular feminization mutation (tfm) leads to loss of hormone binding capacity. Individuals with testes but female external phenotype develop. In the mouse the interaction of androgen insensitive Tfm cells with normal cells can be studied in mosaic individuals composed of both cell types, and in organ culture by recombination of Tfm and normal tissues. The experiments show that under the action of testosterone the normal cells express male differentiated cellular functions, whereas the Tfm cells differentiate in female direction. In respect to proliferation and expression of male or female organ structures, however, both cell types communicate via local factors. Thus, instead of irregular malformations intersex organs develop.
Animals↗
Nuclei in testicular feminization (Tfm) are not activated by intact testosterone receptor complexes: a morphometric study in striated urethral muscle of mosaic mice.
Sex reversed mice heterozygous for the X-linked Tfm mutation are mosaics with respect to the Tfm locus. In the androgen-dependent striated urethral muscle, nuclei coding for the intact testosterone receptor protein and nuclei coding for the defective Tfm receptor protein are incorporated in the same multinucleate muscle fibres. The intact testosterone receptor complex can thus be expected to enter the Tfm nuclei. Our measurements show that the fibre diameters of the mosaic muscle form a homogeneous population, intermediate in size between induced male and non-inducible Tfm phenotypes. By contrast, the nuclear size shows a bimodal distribution, the subpopulations corresponding to Tfm and wild type nuclei. The results indicate that the Tfm nuclei are not activated by the intact testosterone receptor complex.
Androgen-Insensitivity Syndrome↗
Demonstration of 2n spermatids in carriers of the "sex reversed" factor in the mouse by Feulgen cytophotometry.
The "Sex Reversed" factor (SXY) leads to development of XX males. The condition is transmitted by XY-Sxr males. The testes of XY-Sxr carriers are characterized by patches of defective spermatogenesis with meiotic failure and appearance of extraordinary large spermatids. In the present study DNA content of the large spermatids is determined by Feulgen DNA measurement using a scanning cytophotometer. The large spermatids in XY-Sxr testes are shown to be 2n.
Animals↗
[Angiographic examinations of the circulatory development of living chick embryos (author's transl)].
In chick embryos of an age of incubation of 5-14 days, the physiological development of the circulation and the morphological differentiation of the arterial system were studied by intravital and postmortal angiography. For the examinations of the living embryos, a special radiographic and injection technique had to be developed. The contrast medium was injected into the umbilical veins and transported by the actions of the embryonic heart. Continuous ECG recordings showed no marked interference of the injections with the cardiac activity. According to the angiographic findings, the circulation is relatively fast within the main arteries, but the capillary perfusion is prolonged and lasts up to several minutes. The average circulatory velocity of the blood stream within the carotid artery increases parallel to the arterial enlargement, whereas the circulatory time decreases and the number of heart beats during the period of carotid opacification does not change to a great extent. By this, a steady transport of gas and nutritional material may be achieved in the growing arterial system.
Angiography↗
Mosaic character of spermatogenesis in carriers of the sex reversed factor in the mouse.
The "sex reversed" factor leads to development of XX male mice. It is inherited on one of the autosomes and transmitted through XY-Sxr carrier males. In the latter, spermatogenesis is studied under the aspect of gene dosis effects produced by the presence of the Sxr factor in addition to the Y chromosome. A mosaic pattern of normal and defective spermatogenesis is described. The defective areas are characterized by failure in late pachytene and metaphase I, and by appearance of spermatids with very large nuclei which degenerate in cap phase. The defects correspond to those observed in X0-Sxr spermatogenesis. Our interpretation is that in the normal areas only the Y chromosome, and in the defective areas the Sxr factor is expressed.
Androgen-Insensitivity Syndrome↗
Identical action of Y chromosome and sxr factor in early testicular development in the mouse.
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Animals↗