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Notes: The origin of the vertebrate gonad and the Müllerian duct are still a matter of debate. According to the majority of recent textbooks, the gonad is a product of the proliferating coelothelium and therefore derived from the mesoderm of the lateral plate region. The Müllerian duct grows parallel to the Wolffian duct, but it is not clear to what extent the latter contributes actively to the development of the former. In the last decade, we reinvestigated early gonadogenesis and Müllerian duct development in a number of vertebrate model species using various morphological techniques (TEM, SEM, immunohistochemistry). The conclusion of our studies is that rudimentary or regressing nephrostomial tubules, particularly cells of their nephrostomes, must be regarded as the immediate precursors of the somatic cells of the gonadal crest and the Müllerian infundibular field. According to this concept, both structures are derivatives of the intermediate mesoderm. Nephrostomial tubules are regular components of the primitive pro- and mesonephros. They connect the nephric tubule or the nephric corpuscle to the coelomic cavity and open into the latter by means of a funnel-like mouth, the nephrostome (coelomostome). In the larval sterlet, Acipenser ruthenus, short, segmentally arranged nephrostomial tubules with well-developed nephrostomes are present in the region of the cranial opisthonephros. Cells of the medial nephrostomial lips proliferate, surround the germ cells that have accumulated in this location and form a continuous gonadal crest. Cells of the lateral nephrostomial lips proliferate also, spread out on the coelomic surface, replace the original flat mesothelial cells over the Wolffian duct and the cranial opisthonephros and form the Müllerian infundibular field. At about 28 days, a flat pocket begins to invaginate the infundibular field. This pocket is the primordium of the Müllerian ostium abdominale. The findings in Acipenser can be generalized and transferred to other vertebrates.

Notes: The feline urogenital junction is situated between the extratesticular rete and the spacious initial segments of the efferent ductules. The rete epithelium is cuboidal to low columnar. The rete cells forming the junction rest on a wavy basal lamina, display deep mutual invaginations, possess central nuclei with several infoldings and form a distinct border with the columnar epithelial cells of the initial segments of the ductuli efferentes. The epithelium of the initial segments is composed of ciliated cells and non-ciliated principal cells. The latter are the dominating type and characterized by an apical brush-border and a supranuclear endocytotic apparatus. The stroma of the extratesticular rete contains an abundance of collagen whereas contractile cells are here generally absent. In contrast, the initial segments of the efferent ductules are surrounded by elastic fibres and a layer of contractile cells. All nerves for the feline urogenital junction come from the nervus spermaticus superior. In the epididymal head, small nerve bundles deviate into the septa between the ductules. Single fibres establish a dense network within the muscular coat of the ductuli. At the transition to the extratesticular rete, this network ends abruptly. Nerve fibres in the confines of the rete are associated with blood vessels or proceed to the testicular interior, but establish no relationships with the rete epithelium or the myofibroblasts of the mediastinum. The nervous network in the walls of the efferent ductules and their initial segments is not only composed of sympathetic but also parasympathetic, non-myelinated fibres. Particularly noteworthy is the abundance of calcitonin gene-related peptide (CGRP)- and substance P (SP)-containing axons around the initial segments. Both neuroproteins are consistent markers for sensory neurones. Taken together, it can be assumed that the entry of seminal fluid and spermatozoa into the efferent ductules is controlled by a regulatory nervous chain provided with afferent and efferent components.

Notes: Histological and electron microscopical examinations of the vaginal epithelium of the cowThe vaginal epithelium of the cow was not uniform. Its structure depended on the place from where a sample was taken, the hormonal status of the animal, and other (individual) factors. From each of 23 cows 11 tissue samples were taken at equal distances from the entire length of the vagina. Some cows had low blood hormone values, others were under gestagen dominance and still others under the influence of estradiol. In cows with low blood hormone values, tissue samples 1 and 2 (E 1 and E 2), which corresponded to the fornix and its junction with the vagina proper, showed an epithelium of one or two layers of cylindrical cells. Tissue samples E 3 to E 5 (cranial half of the vagina) were dominated by an epithelium consisting of three layers, i. e. two layers of basal cells and one variably shaped layer of apical cells. In E 6 to E 10 (caudal half) the height of the epithelium increased from three to about ten cell layers; a stratum intermedium of variable thickness could be discerned. Tissue sample Ell (vestibule) had a non-cornified squamous epithelium of multiple layers. Cows under the influence of gestagen had an epithelium which in principle was similar to the above findings. In cows under the influence of estradiol, the rate of cell proliferation was increased, the epithelium was thicker throughout, showed an active tendency of desquamation, and that in the vestibule had the potential to become cornified. Free cells (lymphocytes and plasma cells) were found in all areas; they were more numerous in animals under the influence of gestagen. In animals under the influence of estradiol also neutrophils were encountered.PAS-positive mucosubstances containing acid groups were found in the apical cells of the cranial end of the vagina. These substances could be responsible for a typical reaction (Kuppenreaktion) in the epithelial type that featured a stratum intermedium. Apart from folds the vaginal epithelium contained genuine intraepithelial and subepithelial glands.

Notes: Am 10. Tag wird der gesamte Nebenhodenkanal von einem einschidi-tigen Epithel ausgekleidet. Am 25. Tag treten in den Segmenten 1 bis 5 (Kopf und Körper) die ersten Basalzellen auf, während Segment 6 mit seiner Differenzierung weit vorauseilt: Das Epithel ist hier mehrreihig und besteht aus kleinen, rundlichen Basalzellen sowie sdilanken, hohen Zylinderzellen mit typischem Stereocilienbesatz. Bei der weiteren Ontogenese des Nebenhoden-epithels lassen eine Reihe von progressiven Merkmalen (Mehrreihigkeit, Stereocilienbesatz, Phosphatasegehalt der Zylinderzellen) eine disto-proximale Entwicklungsrichtung erkennen: Die Differenzierung des Schweinenebenhodens hat im Gegensatz zu den Verhältnissen bei Ratte und Kaninchen vorwiegend aszendierenden Charakter. Trotzdem wird in alien 6 Segmenten des Ductus epididymidis die definitive Ausformung des Epithels erst in der Endphase der Pubertat zwischen dem 140. und 160. Tag erreicht.〈section xml:id="abs1-2"〉〈title type="main"〉SummaryHistological and histochemical examinations of the postnatal developing epididymis of the pigAt postnatal day 10, the whole length of the epididymal duct is lined with a single layer of epithelial cells. At day 25, the first basal cells appear in segments 1 and 5 (caput and cauda), while in segment 6 cell differentiation is precocious in that the epithelium there has several layers consisting of small, round basal cells and tall cylindrical cells with typical stereocilia. Later, developmental criteria such as epithelial stratification, appearance of stereo-cilia, phosphatase content and appearance of cylindrical cells, indicate a disto-proximal (toward the testis) developmental progression. Thus, in contrast to the differentiation of the rat and rabbit epididymidis that of the pig shows ascending (toward the testis) progression. Nevertheless, in all 6 segments of the duct the definitive differentiation of the epithelium is not reached until the end of puberty (day 140 to 160).〈section xml:id="abs1-3"〉〈title type="main"〉RésuméRecherches histologiques et histodiimiques sur l'ontgénèse postnatale de l'épididyme chez le PoreAu 10éme jour, la totalité du canal épididymaire est revêtue d'un épithélium unistratifié. Au 25ème jour, les premières cellules basales apparais-sent dans les segments 1 à 5 (tête et corps) tandis que le segment 6 montre une différenciation largement plus avancée: l'épithélium y est plus stratifié et se compose de cellules basales petites et arrondies ainsi que des cellules cylindriques, hautes et élancées, pourvues de bordure en brosse typique. Au cours de Pontogenese ulterieure de l'epithélium épididymaire, la série des caractéristiques progressives (pluristratification, bordure en brosse, teneur phosphatasique des cellules cylindriques) suit une direction disto-proximale. La différenciation de l'épididyme du Pore, contrairement à. celle du Rat et du Lapin, présente, d'une manière prépondérante, un caractère ascendant. Cependant, l'achèvement épithélial définitif ne sera atteint, dans les 6 segments du canal épididymaire, que lors de la phase terminale de la puberté, entre les 140ème et 160éme jours.〈section xml:id="abs1-4"〉〈title type="main"〉ResumenInvestigationes histológicas e histoquímicas sobre el desarrollo del epidídimo en el cerdoAl 10° día todo el conducto epididimario está revestido de un epitelio monoestratificado. El día 25, se presentan las primeras células basales en los segmentos 1 a 5 (cabeza y cuerpo), mientras que el segmento 6 adelanta su diferenciación mucho más: el epitelio está dispuesto en varias filas y se compone de células basales pequeñas y redondas, y de células cilíndricas altas y delgadas con sus estereocílias típicas. Durante la ontogénesis ulterior, ciertas características (pluriestratificación, presencia de estereocílias, contenido en fosfatasa alcalina de las células cilindricas) permiten apreciar una progresión en sentido disto-proximal: de tal manera, la diferenciación del epidídimo presenta un caracter ascendente ascendente en el cerdo, en contraste con la rata y el conejo. No obstante, la formación definitiva del epitelio de todos los 6 segmentos del conducto epididimario só1o se alcanza entre los días 140 y 160 del desarrollo.

Notes: Am Terminalsegment des Tubulus seminiferus des geschlechtsreifen Bullen lassen sich drei Abschnitte, nämlich die Ubergangsregion, der Mittelabschnitt und der terminale Pfropf unterscheiden. Mittelabschnitt und terminaler Pfropf werden fast ausschließlich von modifizierten Stützzellen gebildet. Jedes Terminalsegment wird von einem Gefäßplexus manschettenartig umgeben. An den Tubulus seminiferus schliefk sich der Tubulus rectus an. Jeder Tubulus rectus beginnt mit einer kelchartigen Erweiterung, die den terminalen Pfropf umfaßt und die dann in einen engen und glattwandigen Kelchstiel übergeht. Rete-wärts vom Kelchstiel findet sich ein durch die Ausbildung von intraepithelialen Invaginationen gekennzeichneter Tubulusabschnitt, der dann in das Rete testis einmündet. Das einschichtige Epithel von Tubulus rectus und Rete testis ent-hält massenhaft freie Zellen (Lymphocyten und Makrophagen), die bis zu 25 % ausmachen können. Im subepithelialen Stroma des Rete testis liegen flache Zellen, die ihrem Phosphatasereichtum nach als kontraktil anzusprechen sind, sowie reichlich elastische Fasern.

Notes: Zusammenfassung In Uterusepithel und Uterindrüsen der geburtsreifen Schafplacenta werden folgende Fermente mit histochemischen Methoden nachgewiesen: NADH-Tetrazoliumreductase, Cytochromoxydase, NAD-spezifische Isocitratdehydrogenase, Succinatdehydrogenase, Lactatdehydrogenase, Glucose-6-phosphatdehydrogenase, β-Hydroxybutyratdehydrogenase, Adenosintriphosphatase, alkalische Phosphatase und Leucinaminopeptidase. Hierbei zeigt sich, daß die mütterlichen Epithelien der paraplacentaren Uterusschleimhaut und der Uterindrüsen ein wesentlich vielseitigeres Enzymmuster als das Septensyncytium innerhalb des Placentoms besitzen. Die Wirkungsweise der nachgewiesenen Fermente bei Bereitstellung und Sekretion der „Uterinmilch” wird diskutiert.

Notes: Abstract  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 3β-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.

Notes: Zusammenfassung 1. Die Seelöwenniere ist eine zusammengesetzte Niere, deren Renculi sich ohne bindegewebige Zwischensepten aneinanderlagern. 2. Das aus Renculi bestehende Gesamtorgan wird an der Oberfläche von einer gemeinsamen Capsula fibrosa überzogen; die Renculi sind durch seichte Furchen voneinander getrennt. 3. Die größeren, noch außerhalb des Parenchyms gelegenen Arterien und die Äste des verzweigten Harnleiters verlaufen nicht parallel. 4. Jeder Renculus wird von 2–4 Aa. renculares versorgt, die sich in der Mark-Rindengrenze in je 3–5 Aa. subcorticales aufteilen. 5. Die Aa. corticales radiatae enden alle durch Teilung in Vasa afferentia. Es gibt demnach keine freien Wipfeläste. 6. Ludwigsche Äste finden sich in sehr geringer Anzahl und zwar nur in der juxtamedullären Rindenschicht. 7. Für die Rindenzone der Einzelnierchen existiert nur ein oberflächliches abführendes Systems, das zu interrenkularen Venen zusammenfließt, die sich ihrerseits in einer einheitlichen, aus dem Hilus renalis austretenden Vena renalis sammeln.

Notes: Summary The boundary tissue of the porcine testicular seminiferous tubule (membrana propria) exhibits a distinct stratification: the basement lamina of the tubular epithelium (a) is followed by a non-cellular layer with collagen fibrils (b), the peritubular cells (d) with an inner (c) and outer (e) basement lamina and finally the intertubular loose connective tissue (f). Fully developed peritubular cells have many morphological features in common with smooth muscle cells, for instance inpocketings of the plasmalemma (pinocytotic vesicles) and a great number of filaments measuring 60–70 Å in diameter. These filaments are fixed at the inner side of the plasmalemma by means of electron-dense structures. The Golgi apparatus, rough endoplasmic reticulum, mitochondria and microtubules prefer a juxtanuclear position. In contrast that is seen in other species the porcine peritubular cells develop many of their characteristic features before puberty. In samples of the 4th day a fine network of filaments is already visible within the cytoplasm. These filaments are strongly augmented at the 25th day, and from now on they are arranged in a regular fashion. Other findings, also, underline an increased activity of the peritubular cells around day 25. At that time the concentrations of histochemically demonstrated alkaline phosphatase, adenosine triphosphatase and glucose-6-phosphatase reach the high levels typical for the stages of further development and the fully differentiated cells. Pinocytotic vesicles appear in great numbers from day 97. At the 140th day the morphology of the porcine peritubular cell is completely developed.