Haide Breucker

Cellular architecture of the lamina propria of human seminiferous tubules

SummaryThe lamina propria of human seminiferous tubules is composed of 5 to 7 cellular layers separated by laminae of extracellular connective-tissue components. By means of immunocytochemical methods the different nature of the cellular layers could be defined for the first time. Based on the light-microscopic demonstration of both desmin-like and vimentin-like immunoreactivity in the inner 3 to 4 layers of the lamina propria, these cells can be identified as myofibroblasts. The outermost one or two cellular layers, on the contrary, only show a vimentin-like immunoreactivity indicating the pure fibroblastic nature of these cells. Therefore, the outermost cellular layers are suggested to be derivatives of the interstitium. In cases of disturbed spermatogenesis, the lamina propria is frequently considerably thickened by an increase in the extracellular matrix components between the cellular layers. Whereas the ultrastructural localization of laminin-, collagen type-IV- and fibronectin-like immunoreactivity remains unaffected in the thickened lamina propria, the desmin-like immunoreactive cells of the inner layers strongly decrease in number and staining intensity. Most probably, the myofibro-blasts lose their myoid characteristics to participate in the secretion of increased amounts of extracellular matrix components, which in turn presumably block the mediation of the lamina propria between the interstitium and the germinal epithelium. It is still unclear whether the thickened lamina propria provokes the disturbance of spermatogenesis or vice versa.

Morphogenesis and fate of the residual body in human spermiogenesis

SummaryIn the human testis the formation of the residual body of the spermatid and its morphological changes during and after spermiation were studied by means of electron microscopy. The caudal cytoplasmic mass of the late spermatid contains a Golgi complex, mitochondria, annulate lamellae, a chromatoid body, flower-like structures, ribosomes, a few large vacuoles, myelin-like membrane profiles and sporadic lipid droplets. When, by detachment of the caudal cytoplasm from the free spermatozoon, the residual body is formed, the chromatoid body has disappeared; the mitochondria are clustered peripherally; the ribosomes appear as a single complex in contact with a large vacuole containing granular material; in place of the Golgi complex aggregations of vesicles are present. The lipid droplets remain unchanged. The residual bodies or their fragments are either extruded via the seminiferous tubular lumen into the excurrent ducts or they are engulfed by Sertoli cells where in the supranuclear region the successive steps of decomposition can be observed. The participation of the various constituents in the disintegration of the residual body is discussed. In contrast to other mammalian species, in man the sporadic lipid droplets seem to be of minor importance in the fate of the residual body.

Ultrastructural studies on the epithelia of the olfactory organ of cyprinodonts (teleostei, cyprinodontoidea)

SummaryThe epithelia of the olfactory organ of two cyprinodontoid fish species were studied both by transmission and scanning electron microscopy. The relatively flat floor of the organ is covered by sensory and nonsensory epithelia. The latter is distributed in the form of bands or ridges separating distinct areas of sensory epithelium. Differences between the olfactory organs of the two species investigated related only to the topography and quantitative distribution of the epithelia. Their ultrastructural features are very similar. The nonsensory stratified squamous epithelium contains numerous goblet cells and surface cells provided with microridges. A hypothetical function of the microridges is discussed. The sensory epithelium consists mainly of basal, supporting, and two types of sensory cells, i.e., ciliated and microvillous receptor cells. The cilia exhibit a predominant 9+0 microtubule pattern. Both epithelia are covered by a mucus layer in which all surface structures seem to be embedded. The possible nature, origin, and movement mechanisms of the mucus are discussed.

Die Spermatogenese der Zecke Ornithodorus moubata (Murr)

SummaryThe genesis of the tailless spermatozoa of the tick Ornithodorus moubata has been studied by light and electron microscopy.In the germ zone of the testis the smallest cells of the spermatogenesis are located, the spermatogonia A which are separated from each other by somatic cells. The result of a multiplication phase with 4 mitoses are clusters of 16 spermatogonia B. While growing up the spermatogonia B differentiate into spermatocytes I. They show a special structure of their border which, after the quickly passed maturation divisions, gets more developed in the spermatides and turns into a vacuole with ribbon-like cytoplasmic processes hanging into it. Simultaneously with an elongation of the spermatide the subsequent apex invaginates into the vacuole and induces an inversion of the spermatide like the finger of a glove. This last step takes place only after the copulation in the female. Then the processes previously hanging into the vacuole are lying as groins close to the outside of the mature spermatozoon. The condensation of the nucleus and the formation of the acrosome are described in particular. Because of the complicated transformation of the spermatide also the nucleus, the acrosome and the centrioles undergo extensive migrations being accomplished in the female.ZusammenfassungDie Genese der schwanzlosen Spermatozoen der Zecke Ornithodorus moubata wurde licht- und elektronenmikroskopisch untersucht.In der Keimzone des Hodens finden sich die kleinsten Zellen der Spermatogenese, die Spermatogonien A, die einzeln durch somatische Zellen voneinander isoliert sind. In einer Vermehrungsphase von 4 Teilungen entstehen Ballen von je 16 Spermatogonien B. Durch Wachstum gehen die Spermatogonien B in Spermatozyten I. Ordnung über. Dabei entsteht in ihnen eine Randstruktur, die sich nach den rasch ablaufenden Reifeteilungen in den Spermatiden zu einer Vakuole entwickelt, in die bandartige Zellfortsätze hineinhängen. Gleichzeitig mit einer Längsstreckung der Spermatide stülpt sich die spätere Spitze in die Vakuole ein und führt zu einer handschuhfingerartigen Umkrempung der Spermatide. Dieser letzte Schritt erfolgt erst nach der Kopulation im Weibchen. Dann liegen die ursprünglich in die Vakuole hängenden Fortsätze dem reifen Spermatozoon außen als Leisten an.Die Kernkondensation und die Akrosombildung werden im einzelnen beschrieben. Durch die komplizierte Umgestaltung der Spermatide erfahren auch Kern und Akrosom sowie die Zentriolen unfangreiche Ortsveränderungen, die erst im Weibchen abgeschlossen werden.

Cytosomale Einschlüsse und Neurosekret im Nervengewebe von Gastropoden

SummaryThe light- and electronmicroscopical structure of neurones, glial cells, extra cellular spaces, and perineurium were investigated in the different sex phases of Crepidula fornicata L. (males, intersexes, females). The electronmicroscopical structures of the granules, present in all nerve cells, are very heterogeneous and similar to those of cytosomes. The origin, growth, and structural changes of the cytosomes are described and their probable function is discussed. The topographical position of the neurosecretory cells in the cerebral ganglia is constant. The secretory products of these cells are transported along the axons partly by a small neurosecretory pathway, but the neurosesecretory system of Crepidula (Prosobranchia) is not so highly developed as that in the cerebral ganglia of other gastropods (for example in pulmonates). The glial cells can be devided into two types according to their different staining, the electronmicroscopical structure of their granules and their position in the central neuropil or in the peripheral layer of nerve cells. The intersexual phase is marked by a more evident content of neurosecretory material and more and larger granules in the peripheral glial cells.

Development of the olfactory organ in the rainbow fish Nematocentris maccullochi (Atheriniformes, Melanotaeniidae)

SummaryThe development of the olfactory organ in the rainbow fish, Nematocentris maccullochi, was studied using scanning and transmission electron microscopy; it was compared with the developmental process in other teleosts, especially in the closely related atherinids and cyprinodonts. The formation of the nares parallels that in atherinids, salmonids, cyprinids and heterosomats, but differs from that found in cyprinodonts. Another ontogenetic feature in which the olfactory organs of the rainbow fish and also of atherinids differ from those of cyprinodonts, is the occurrence of transitory kinociliary cells which disappear during the postlarval period. The divergent evolutionary pathways are discussed with reference to experimental investigations. During development, ciliated and microvillous receptor cell types occur. At the primary larval stage ciliated receptor neurons are exclusively present. At a later stage the microvillous type develops and becomes equal in frequency. Thus, the microvillous receptor represents a separate type of olfactory neuron and is not a progenitor of the ciliated receptor cell.

Macrophages, a normal component in seasonally involuting testes of the swan, Cygnus olor

SummaryIn the swan, Cygnus olor, spermatogenesis shows a pronounced seasonal cycle. During the long involution phase a transient invasion of macrophages into the seminiferous tubules regularly takes place at the height of regression prior to total rest. These macrophages are involved in the additional disposal of supernumerary and degenerating premature germ cells, at a time when the Sertoli cells are already filled with phagolysosomes.

Spermatozoen und Spermiohistogenese vonGraphidostreptus spec. (Myriapoda, Diplopoda)

SummaryThe mature spermatozoa of the African millipedeGraphidostreptus spec. (Diplopoda) were studied by light and electron microscopy. The hat-like spermatozoa are combined two by two in spermatophores. They consist of a plate containing a disk-like nucleus, and a cylinder containing the acrosomal complex. — The free border of the hat and a basal layer below the caryoplasma are formed by a very electron-dense cytoplasma with hemispheric protrusions on the basal side. The basal cytoplasma contains light canaliculi with a diameter of about 100 Å. — There is no membrane around the caryoplasma which is composed of an electrondense substance. It is completely filled up with long and light canaliculi with a diameter of 400 Å. These canaliculi contain an electron-dense tubulus of about 200 Å diameter, in the axis of which a filament of about 40 Å diameter is to be found. — In the border of the nucleus on its dorsal side there is a circle of mitochondria. — The acrosomal complex building up the cylinder is composed of an envelope of striated material below the cell membrane, of a nail-like acrosomal vacuole, of a body appearing in section like a M, of a hemispheric calotte, and of a cristalloid lying in the center.ZusammenfassungDie reifen Spermatozoen des afrikanischen TausendfüßlersGraphidostreptus spec. (Diplopoda) wurden licht- und elektronenmikroskopisch untersucht.Die hutförmigen Spermatozoen sind paarweise in Spermatophoren vereinigt. Sie bestehen aus einer den scheibenförmigen Kern enthaltenden Platte und einem Zylinder, in dem sich der Akrosomkomplex befindet. — Der freie Rand des Hutes und eine basale Schicht unter dem Karyoplasma werden von sehr elektronendichtem Zytoplasma gebildet, das basal halbkugelige Vorwölbungen besitzt. Das basale Zytoplasma enthält helle Röhrchen von ca. 100 Å Durchmesser. — Dem Karyoplasma fehlt eine Kernmembran. Es besteht aus einer elektronendichten Substanz und ist vollständig von langen, 400 Å dicken hellen Röhrchen durchsetzt. Die Röhrchen enthalten einen elektronendichten Tubulus von 200 Å Durchmesser, in dessen Achse ein ca. 40 Å dickes Filament liegt. — In den Rand des Kernes ist dorsal ein Ring von Mitochondrien eingelassen. — Der den Zylinder bildende Akrosomkomplex besteht aus einem Mantel streifigen Materials unter der Zellmembran, aus der nageiförmigen Akrosomvakuole, einem im Schnitt M-förmigen Körper, einer halbkugeligen Kalotte und einem zentral gelegenen Kristalloid.

Spermatozoen und Spermiohistogenese von Spirostreptus spec. (Myriapoda, Diplopoda)

SummaryThe spermiohistogenesis of the spermatozoa of Spirostreptus which have no tails has been studied by means of light and electron microscopy. The development can be divided into a sequence of five phases. — 1. phase: Thickening of the cell-membrane of the spermatide, arrangement of the mitochondria as a cap at the apical periphery of the nucleus. The centriol is situated near the apical pole of the nucleus. — 2. phase: The differentiation of the acrosomal complex starts with the formation of an acrosomal vacuole; between this vacuole and the nucleus the “calotte” appears. In addition to the calotte an annulus arises produced by material out of the nucleus. Later on the annulus increases to the M-like body. Between this body and the calotte the first portions of the cristalloid appear. — 3. phase: Increase of the acrosomal complex, especially of the M-like body and the cristalloid; during this period the nucleus flattens and the mitochondria cap, now forming a ring, moves with the centriol beside the plate-like nucleus. The basal cytoplasma becomes outlined. The particular structure of the “envelope” appears. — 4. phase: Transformation of the structure of the caryoplasma. In the first two phases parts of chromosomes are to be found in the caryoplasma. In the third phase the caryoplasma becomes homogeneous, and in the fourth phase primarily filaments appear which condense as skeins of caryoplasma. At the same time the gap of the basal nucleus envelope disappears and is filled by a complex of membranes. Beneath the apical and the lateral part of the envelope cisterns and tubules appear within the nucleus. — 5. phase: After separation of the basal cytoplasma the caryoplasma becomes lamellar. Primarily the lamellae are orientated two by two, later on various and finally all lamellae are situated parallel to each other. Then between adjacent lamellae junctions are formed by means of which the tubular structure of the caryoplasma of the mature spermatozoa originates. — The results are discussed and compared with the findings of similar forms of spermatozoa.ZusammenfassungDie Spermiohistogenese der schwanzlosen Spermien von Spirostreptus wurde licht- und elektronenmikroskopisch untersucht und in 5 Phasen dargestellt. — 1. Phase: Verdickung der Spermatidenmembran, Anordnung der Mitochondrien in einer Kappe um den apikalen Kernumfang. Das Zentriol liegt nahe dem apikalen Kernpol. — 2. Phase: Die Differenzierung des Akrosomkomplexes beginnt mit der Akrosomvakuole; zwischen ihr und dem Kern entsteht die „Kalotte“ und durch Materialaustritt aus dem Kern ein Ring um die Akrosomvakuole, der sich später zum M-Körper vergrößert. Zwischen M-Körper und Kalotte treten die ersten Anteile des Kristalloids auf. — 3. Phase: Vergrößerung des Akrosomkomplexes, besonders des M-Körpers und des Kristalloids, wobei sich der Kern abplattet und die Mitochondrienkappe als Mitochondrienring mit dem Zentriol an die Seite des scheibenförmigen Kernes tritt. Das basale Zytoplasma wird abgegrenzt. Die Mantelstruktur tritt auf. — 4. Phase: Umstrukturierung des Karyoplasma. In den ersten beiden Phasen sind im Karyoplasma noch Chromosomenteile zu finden. In der 3. Phase wird das Karyoplasma homogen, und in der 4. Phase treten zuerst Filamente auf, die sich zu Karyoplasmasträhnen verdichten. Gleichzeitig wird der basale Kernplasmaspalt zu einem Membrankomplex geschlossen. Unter der apikalen und seitlichen Kernmembran treten intranukleäre Zisternen und Tubuli auf. — 5. Phase: Nach Abstoßung des basalen Zytoplasmatropfens wird das Karyoplasma zunächst lamellar. Die Lamellen legen sich erst paarweise, später zu mehreren und schließlich alle parallel aneinander. Zwischen benachbarten Lamellen werden dann Querwände ausgebildet, wodurch die Röhrchenstruktur des Karyoplasma reifer Spermien entsteht. — Die Ergebnisse werden besprochen und mit den Befunden an ähnlichen Spermienformen verglichen.

DIFFERENT EPITHELIA IN THE DISTAL HUMAN MALE URETHRA

SummaryThe distal segment of the human male urethra, in particular the fossa navicularis, was studied with light- and electron microscopy as well as by means of histochemical and immunocytochemical methods. The fossa navicularis of the urethra contains a circumscribed zone of extremely thick, non-keratinized stratified squamous epithelium composed of cells containing a large amount of glycogen. These cells lack acid phosphatase activity and lysozyme-like immunoreactivity, both of which can be demonstrated to varying extents in the other zones of the distal male urethra. These glycogen-rich cells are considered to be the substrate for an endogenous flora of lactobacteria, whereas the acid-phosphatase activity and the lysozyme-like immunoreactivity indicate the presence of macrophages and the secretion of bactericidal agents at the epithelial surface. These observations suggest that the different zones with heterogeneous properties in the distal male urethra probably represent a defense system against the invasion of pathogenic microorganisms. Moreover, the glycogen-rich zone, which resembles the glycogen-rich epithelium of the vagina, is estrogen-dependent. This is demonstrated in cases of sex reversal in which after long-lasting estrogen treatment the glycogen-rich zone becomes extremely extended by displacement of the neighbouring epithelium.