Blood parasites of sheep in the Netherlands. I. Anaplasma mesaeterum sp.n. (Rickettsiales, Anaplasmataceae)

Summary On two occasions an anaplasm was isolated from sheep on the Dutch island of Ameland. The organism proved to be highly pathogenic for splenectomised sheep; a non-splenectomised animal recovered spontaneously after the packed cell volume had decreased by 40%. Treatment with oxytetracycline was effective. Its pathogenicity for goats appeared to be low, and the organism was apparently not infective to splenectomised cattle. This anaplasm differs from Anaplasma ovis in that less than 30% of the organisms are marginally situated in the red cell, as against over 70% in A. ovis; cross-immunity with A. ovis was incomplete and the latter appeared to be far more pathogenic to goats than the Dutch anaplasm, for which the name Anaplasma mesaeterum sp.n. is proposed. Its ultrastructure is similar to that of A. marginale and A. ovis. The vector is either Ixodes ricinus or Haemaphysalis punctata. Its practical importance remains to be ascertained.

The major bovine mastitis pathogens have different cell tropisms in cultures of bovine mammary gland cells

We previously showed that Staphylococcus aureus cells adhered mainly to an elongated cell type, present in cultures of bovine mammary gland cells. Moreover, we showed that this adhesion was mediated by binding to fibronectin. The same in vitro model was used here, to study adhesion of other important mastitis pathogens. Like the S. aureus strains, the Streptococcus dysgalactiae strains adhered mainly to elongated cells, which seemed to be mediated by fibronectin binding. In contrast, Streptococcus uberis strains adhered mainly to cubic cells. Since the cubic cells did not express fibronectin and S. uberis cells bound fibronectin less efficiently, the adhesion of S. uberis cells was independent of fibronectin binding. Streptococcus agalactiae strains adhered poorly to both cell types. The specificity and efficiency of adhesion of Escherichia coli strains was strongly strain dependent. None of the S. agalactiae and E. coli strains tested was able to bind fibronectin efficiently. The results suggest that the different mastitis pathogens have different target cell specificities and use different mechanisms to adhere to cells of the bovine mammary gland.

Penile bulb and its relationship with the pelvic urethra and the penile urethra in the rat: light and scanning electron microscopical observations

BACKGROUND

In male rats the urethral tract consists of the following parts: the pelvic urethra, the transitional urethra, the urethral diverticle, and the penile urethra. Perusal of the literature results in only some more general descriptions and a very few which go more into detail. None of the latter deals with all the compartments nor with the relationships between each other. Aim of this study is to give a detailed morphological study of all the urethral compartments and their relationships to provide a platform for further experimental investigations.

METHODS

From 40 adult male Wistar rats the urethral tract has been investigated by histology and scanning electron microscopy using intact tissue and casting techniques.

RESULTS

Most striking is the existence of the sinusoids in the spongious tissues in the pelvic urethra into a system of two perpendicular layers of parallel sinusoids. In the spongious tissues of the penile corpus spongiosum the same organization can be found although less prominent. Smooth muscle cells are very unequally present along the urethral tract. In its pelvic part they do not form a continuous layer around the spongious tissue and compared to the distal part they appear proximally more abundant. In the bulbal part of the corpus spongiosum the smooth muscles form a massive sac around the spongious tissue. In the corpus spongiosum in the penile shaft they are absent. The smooth muscle cells are separated from the striated urethral muscle by a very thin layer of connective tissue, in the penile bulb a prominent tunica albuginea separates them from the striated penile muscles. In the spongious tissues of the pelvic urethra and the penile bulb large amounts of compound urethral glands are present. Their ducts open into the respective lumen. Helicine arteries are common in the pelvic urethra, especially in the glandular tissue. They are also normally present in the wing tips of the penile bulb.

CONCLUSIONS

The transitional urethra, the urethral diverticle and surrounding spongious tissue are structurally closely related to the other parts, however their microscopical organization is intermediate between the pelvic part of the urethra and the corpus spongiosum. The highly ordered sinusoids in the spongious layers especially in the pelvic part together with a similar organization of the urethral muscle provide a possible basis for a peristaltic driving mechanism, suggesting these structures play a role in the high speed transport of sperms during ejaculation.

The periplasmic flagella of Serpulina (Treponema) hyodysenteriae are composed of two sheath proteins and three core proteins

The major components of the periplasmic flagella of the spirochaete Serpulina (Treponema) hyodysenteriae strain C5 were purified and characterized. We demonstrate that the periplasmic flagella are composed of five major proteins (molecular masses 44, 37, 35, 34 and 32 kDa) and present their location, N-terminal amino acid sequence and immunological relationship. The 44 kDa and the 35 kDa protein are on the sheath of the periplasmic flagellum, whereas the 37, 34 and 32 kDa protein reside in the periplasmic flagellar core. The two sheath flagellar proteins are immunologically related but have different N-terminal amino acid sequences. The N-terminus of the 44 kDa protein shows homology with the sheath flagellins of other spirochaetes, but the 35 kDa protein does not. The three core proteins are immunologically cross-reactive and their N-terminal amino acid sequences are almost, but not completely, identical, indicating that the core proteins are encoded by three distinct genes. The core proteins show extensive N-terminal sequence similarities and an immunological relationship with periplasmic flagellar core proteins of other spirochaetes.

Effect of pregnant mares' serum gonadotrophin on the micromorphology of antral follicles in heifers, with special reference to atypical granulosa cells

Five Dutch-Friesian heifers were injected i.m. with 3000 iu pregnant mares' serum gonadotrophin (PMSG) on day 10 of the oestrous cycle, to study the effects on the number and micromorphological quality of antral follicles (> or = 0.3 mm in diameter). The ovaries were collected 48 h after PMSG injection. As well as the presence of mitotic figures and the absence of pyknotic nuclei in the granulosa, atypical granulosa cells were found in nonatretic follicles. These cells had an oblong nucleus and stained with toluidine blue. They were characterized by their dark cell matrix, and the presence of numerous free ribosomes and intermediate filaments of varying quantity. Atypical granulosa cells were micromorphologically similar to fibroblast-like cells in the theca. Their presence coincided with the occurrence of degenerative changes in the cytoplasm of nearby granulosa cells and they were more frequent in atretic follicles. The presence of atypical granulosa cells in follicles hitherto called nonatretic is therefore probably associated with the onset of follicular atresia. In the PMSG-treated heifers, the mean number of large (> or = 6.0 mm in diameter) antral follicles was greater than in the control group (18.4 +/- 4.0 versus 3.0 +/- 1.0), because of an increase in the number of large nonatretic follicles (11.8 +/- 4.4 versus 0.4 +/- 0.2). After hormone treatment, the mean number of medium-sized (3.0-5.9 mm) nonatretic follicles also increased (6.4 +/- 1.3 versus 1.8 +/- 1.0). PMSG did not change the mean number of nonatretic follicles < 3.0 mm or that of atretic follicles in the different size categories. However, when follicles hitherto called nonatretic, with atypical granulosa cells, were taken together with the group of atretic follicles, PMSG appeared to increase the mean number of large atretic follicles (13.6 +/- 2.4 versus 3.0 +/- 1.0). The mean number of medium-sized and large nonatretic follicles without atypical granulosa cells was markedly increased (3.8 +/- 1.0 versus 0.2 +/- 0.2 and 4.6 +/- 1.9 versus 0.0, respectively). The data demonstrate that PMSG stimulates the formation not only of nonatretic follicles > or = 3.0 mm, but also of atretic follicles > or = 6.0 mm.

The ultrastructure of normal fetal and neonatal pig testis germ cells and the influence of fetal decapitation on the germ cell development

The development of germ cells in the male pig was investigated ultrastructurally in normal and decapitated fetuses. The age ranged respectively from 30 days p.c. till one month after birth and from 52 days p.c. until birth. The ultrastructural organization of the germ cells changes dramatically between 30 days p.c. and 52 days p.c. which coincides with the formation of ‘true’ sex cords. From 52 days p.c. onwards the morphology is rather stable: cells show a ‘hydrated’ appearance and typical cell bridges. There is no obvious difference in the ultrastructure of germ cells in decapitated animals, their normal littermates and control animals. Therefore germ cell development in the pig is likely to be insensitive to gonadotropins during the fetal period. The development of pig germ cells follows closely the pattern described for several species. Quantitatively there is an increase in the ratio of germ cell/Sertoli cell per cross sectional diameter in the decapitated animals.

Sertoli cell development of pig testis in the fetal and neonatal period

The Sertoli cells of pig fetuses from 35 days postcoitum until 1 mo after birth have been investigated by light and electron microscopy in decapitated animals and their control littermates, as well as in untreated animals. Until 52 days postcoitum, Sertoli cells change in form during the formation of sex cords but from then onwards they are rather uniform. They primarily display an elongated nonindented nucleus with one or more prominent nucleoli, a well-developed Golgi apparatus, and in the basal compartment below or beside the nucleus, a large lipid droplet. There are large quantities of rough endoplasmic reticulum (RER) from 52 days postcoitum onwards, often with complex whirl forms and a parallel arrangement of profiles with relatively few ribosomes. After birth their numbers seem to be somewhat less, and by 1 mo after birth the RER profiles are often shorter and almost free of ribosomes. Clustered ribosomes are found in large quantities throughout the period under investigation. Especially in the early fetal period, the endoplasmic reticulum (ER) profiles show prominently filled cisternae. Mitochondria are mostly long and slender, or small and ovoid. Most have lamellar cristae, but mixed lamellar-tubular cristae can also be seen. Between decapitated, control and untreated animals no obvious ultrastructural differences could be observed. The peritubular cell sheath surrounding the sex cords did not show signs of differentiation into a layer of myoid cells.

Cytoplasmic filaments in fetal and neonatal pig testis

Leydig cells in developing fetal pig testis contained during the fetal regressive phase large accumulations of intermediate filaments. Before and after this period these filaments were arranged in a criss-cross fashion. In the pig as well as in the dog testis these filaments have been characterized as vimentin. Within the vimentin aggregates occasionally a weak positive actin reaction was seen in pig but not in dog Leydig cells. Microfilaments were hardly observed. Most Sertoli cells contained a layer of actin microfilaments close to the basal cell membrane. In the lower cell compartment and around the nucleus (intermediate) vimentin filaments could be observed in a criss-cross configuration.

Leydig cell development in the pig testis during the late fetal and early postnatal period: an electron microscopic study with attention to the influence of fetal decapitation

The ultrastructure of fetal and postnatal pig Leydig cells was studied from 75 days postcoitum (p.c.) to 1 month after birth. Additionally, decapitated fetuses from 75 days p.c. until birth were used to study the effect of deprivation of gonadotrophins on the ultrastructure of Leydig cells. Normal Leydig cell development was characterized by a change in smooth endoplasmic reticulum (SER). Next to branched tubular SER, whirls of elaborate and tightly packed SER membranes appeared. The amount of SER increased with age but decreased slightly before the end of the observation period. Rough endoplasmic reticulum (RER) was a minor component. Large bundles or whirls of intermediate filaments were abundant until just before birth; thereafter, they decreased drastically. Peroxisome-like structures and crystalloid bodies were observed with increasing frequency from 75 days p.c. and 20 days postpartum onward. Polygonal lysosome-like dense bodies transformed into complex membranous structures especially after birth. Giant mitochondria occurred in the late fetal and postnatal period. From 75 days p.c. onward fully developed Leydig cells were scarce in testes of decapitated fetuses. Leydig cell characteristics disappeared toward the end of the fetal period; only the cell shape, the large bundles or whirls of intermediate filaments, some scarce polygonal lysosome-like dense bodies, and RER remained, but SER was negligible. Progressive hemorrhages apparent in situ were correlated positively with fetal age. The dependency of Leydig cells upon LH began between 60 and 75 days postcoitum.

Leydig cell development of pig testis in the early fetal period: an ultrastructural study

Leydig cell development in the pig testis occurs in three periods (an early fetal, the perinatal period, and the period from puberty onward). The earliest of these periods was investigated ultrastructurally. The early fetal period starts immediately after gonadal differentiation, approximately 27 days postcoitum (p.c.), and finishes at about 60 days postcoitum. Dates of observation were 35, 52, and 62 days p.c. At 42 days p.c. some animals were decapitated. Leydig cells at 35 days p.c. are characterized by an oval nucleus, vesicular or branched tubular smooth endoplasmic reticulum (SER), and a small quantity of rough endoplasmic reticulum (RER). The RER has two forms: a short and a long profile. The latter is closely coupled with mitochondria. The mitochondria mostly have tubular cristae. From 52 days p.c. onward the degree of coupling lessens, and it vanishes at 62 days p.c. At 52 and 62 days p.c. a very large amount of 10 nm filaments and a slight decrease in SER can be observed. The SER now has a branched tubular form, and the presence of polygonal dense bodies is also characteristic. Decapitation does not disturb normal development of the Leydig cells in the observation period. No obvious differences from controls can be observed.

Blood parasites of sheep in the Netherlands. I. Anaplasma mesaeterum sp.n. (Rickettsiales, Anaplasmataceae)

On two occasions an anaplasm was isolated from sheep on the Dutch island of Ameland. The organism proved to be highly pathogenic for splenectomised sheep; a non-splenectomised animal recovered spontaneously after the packed cell volume had decreased by 40%. Treatment with oxytetracycline was effective. Its pathogenicity for goats appeared to be low, and the organism was apparently not infective to splenectomised cattle. This anaplasm differs from Anaplasma ovis in that less than 30% of the organisms are marginally situated in the red cell, as against over 70% in A. ovis; cross-immunity with A. ovis was incomplete and the latter appeared to be far more pathogenic to goats than the Dutch anaplasm, for which the name Anaplasma mesaeterum sp.n. is proposed. Its ultrastructure is similar to that of A. marginale and A. ovis. The vector is either Ixodes ricinus or Haemaphysalis punctata. Its practical importance remains to be ascertained.

Is Mukherjeella caprae Bandaranayake and Neitz, 1961 (Rickettsiales) a microorganism?

Longitudinal structures in red cells in Giemsa-stained blood smears of goats in the Netherlands were in distinguishable from what has been described as Mukherjeella caprae Bandaranayake and Neitz, 1961 (Rickettsiales). Electron microscopic studies and animal experiments showed, however, that these structures are not parasitic in nature, but are fibres consisting of bundles of microfilaments embedded in the erythrocytic cytoplasm, apparently identical with the longitudinal fibres in goat erythrocytes which are considered to be a haemoglobin abnormality. The condition appears to be genetic. M caprae should be considered as a nomen dubium.

Erythrocytic forms of Theileria velifera

The enigmatic veil associated with the cattle parasite Haematoxenus veliferus has been shown to be crystallike in ultrastructure and to stain with benzidine like haemoglobin. The ultrastructure of the organism is similar to that of other theilerial parasites. As less distinct veil-like structures are known to occur with some other Theileria species, and in one case, have also been shown to be crystalline in structure, it is proposed to sink the genus Haematoxenus as a synonym of Theileria.

The secretory activity of the epithelium of the ampulla tubae in cyclic ewes: an electron microscopical study

The ultrastructural organization of the epithelium of the ovine oviduct was studied with special reference to cyclical changes in synthesis, storage, and release of the secretory product. In contradistinction to the ciliated cells, the secretory cells have a conspicuous endoplasmic reticulum especially on the first days after onset of heat. Several types of secretion granules can be distinguished; they possibly represent different stages of maturation. The younger forms predominate during the first days of the cycle. Release of the secretory product can be observed mainly during this period, but also occur during later stages of the cycle. The peak level of oestradiol-17theta, occurring in the blood on D 16 (D 0 is the first day of heat), is presumed to be responsible for the increase in synthesizing capacity of the secretory cells during heat and first following days. The endocrine control of the release of the secretory product remains obscure: progesterone does not seem to play an essential role.