Polyol pathway along the bovine epididymis

During the epididymal transit, male gametes acquire new surface proteins necessary for their fertilizing ability. We have previously shown that membranous vesicles, called epididymosomes, interact with sperm surface within the epididymal fluid allowing transfer of some proteins to different subcellular compartments of spermatozoa. We previously showed that one of the major proteins associated with epididymosomes was an aldose reductase (gene: AKR1B5) and confirmed that aldose reductase is located in the epithelial cells bordering the intraluminal compartment of the epididymis. The present study shows that cytosolic aldose reductase activity was maximal in the proximal and middle segments of the epididymis and decreased in the distal epididymis. Western and Northern blot analysis confirmed the distribution pattern of aldose reductase and of the encoding mRNA. The optimal pH of epididymal aldose reductase was 6.0-6.5 when glucose was used as a substrate; this corresponds to the pH of the intraluminal epididymal fluid. In order to evaluate the possible involvement of sorbitol in sperm physiology, Western blot of tissue homogenates were probed with an anti-sorbitol dehydrogenase antibody. The amount of enzyme immunodetected was higher in the proximal and distal segments of the epididymis when compared to the amount detectable in the middle segment of the epididymis. Sorbitol dehydrogenase activity as well as the level of the encoding mRNA showed the same pattern of distribution. Furthermore, immunohistological studies using the anti-sorbitol dehydrogenase revealed that this enzyme was synthesized by the epididymal epithelial cells bordering the intraluminal compartment. Knowing the importance of sorbitol and fructose in sperm metabolism, we hypothesized that the polyol pathway is involved in the modulation of sperm motility within the epididymis.     

Morphology of immature bovine oocytes

Bovine cumulus oocyte complexes (COCs) as used for in vitro maturation and fertilization can be classified into different categories by light microscopical inspection. We have distinguished four categories based on compactness and transparency of the cumulus investment and homogeneity and transparency of the ooplasm. The four categories were studied for their morphological characteristics at the ultrastructural level and for their developing capacity in an in vitro maturation system. In categories 1 and 2 oocytes, organelles were evenly distributed. In categories 3 and 4, oocytes organelles were clustered and the distribution of the organelles mimicked the characteristics of oocytes during final maturation. Cumulus cell process endings penetrated the cortex of the oocyte or were located superficial to the cortex of the oocyte. In category 1 oocytes, most of the process endings penetrated the cortex. In category 4 oocytes, most of the process endings did not penetrate. In categories 2 and 3 oocytes, both forms of process endings did occur. After in vitro maturation, only category 4 oocytes showed a decreased developing capacity. Categories 1–3 oocytes showed equal developing capacity in an in vitro maturation system.     

Morphology of the bovine Sertoli cell during the spermatogenetic cycle

Summary The morphology of the bovine Sertoli cell was studied during 6 different phases of the spermatogenetic cycle. Tubular dimensions do not vary significantly during the phases. Sertoli cells occupy 27.0% (phase 4) to 38.4% (phase 8) of the tubular epithelium. Sertoli cells of phase 1 are approximately 20% larger than during the other phases. 30–35% of Sertoli cell volume consists of organelles. Mitochondrial (about 5.0%) and nuclear (about 5.7%) volume densities remain remarkably stable during the cycle, irrespective of changes in Sertoli cell size. Phagocytic capacity of bovine Sertoli cells is only moderate. Elimination of excess spermatid cytoplasm occurs to a large extent prior to spermiation. The majority of spermatid residual bodies undergoes autolytic decay while attached to the Sertoli cell apical surface. Aggregates of densely packed cisternae of the smooth endoplasmic reticulum (ER) located in a basal position and associated with the acrosome-phase and maturation-phase spermatids contribute between 14 and 17% to Sertoli cell volume. During phase 3 the ER pinches off a large number of small, smooth-walled vesicles filled with flocculent content. The contact area between Sertoli cells and other tubular constituents changes considerably during the different phases. It is concluded that the blood-testis barrier is particularly impassable during phases 1 and 8. A lipid cycle does not exist in the bovine testicular tubular epithelium.     

Morphology of globule leucocyte from bovine bronchopulmonary lavage

It has hitherto been assumed that the globule leucocytes (GL) occur as free cells in the airways of animals. The present study provides definite evidence for the occurrence of these cells in the bronchopulmonary lavage of cattle. At the light-microscopic level, the GL was a round to elongate cell containing the characteristic large, round, metachromatic granules and an eccentric nucleus with a prominent nucleolus. Ultrastructurally, the cell was round, approximately 15 micron in diameter, and contained round, electron-dense granules which measured approximately 1.25 micron in diameter. The cell nucleus was endowed with abundant heterochromatin. The cytoplasm had only inconspicuous organelles. We conclude that the bovine GL is a specific cell which reaches the airway lumen following migration from the lining of the bronchopulmonary mucous membrane.     

Morphology of inhibited larvae of the bovine lungworm Dictyocaulus viviparus.

Some morphological features of inhibited fourth stage (L4) and fourth moult larvae (4M) of the bovine lungworm Dictyocaulus viviparus are described. Inhibition was induced by maintaining the third stage larvae (L3) for 6 weeks at 4 degrees C. Inhibited fourth stage (L4) and fourth moult larvae (4M) were collected by perfusion of the lungs of experimentally infected calves after necropsy at 15 and 68 days post infection (d.p.i.), respectively. Inhibited 4M, isolated at 68 d.p.i., were about ten times larger than inhibited L4 isolated at 15 d.p.i.     

Tuberculosis of the epididymis

Genital tuberculosis is usually associated with tuberculous involvement of the kidney. A case is reported of clinically isolated tuberculosis of the epididymis     

Morphology of preovulatory bovine follicles as related to oocyte maturation

Thirty-three preovulatory bovine oocytes and their follicles were collected during the period of final maturation in normally cyclic cows. Cell density of the membrana granulosa, mitotic index of the membrana granulosa, and the occurrence of eosinophylic granulocytes around the basal membrane as well as the maturational stage of the oocyte were determined. Cell density decreased during the period of final maturation. Mitotic indices also decreased after an initial high level in the first hours of the final maturation. Eosinophylic granulocytes were only seen during the last hours of final maturation. The maturational stages of the oocytes were related to distinct maturational stages of the follicular wall as determined by morphological characteristics. We propose a scoring system for the maturity of the follicular wall based on cell density, presence of mitotic figures and the presence of eosinophylic granulocytes outside the vascular compartment.     

Aldose reductase and macrophage migration inhibitory factor are associated with epididymosomes and spermatozoa in the bovine epididymis

During the epididymal transit, mammalian spermatozoa acquire new surface proteins necessary for male gamete function. We have previously shown that membranous vesicles, called epididymosomes, interact with spermatozoa allowing the transfer of some proteins to sperm surface within the epididymal lumen. The protein composition of those vesicles has been investigated to document the mechanisms of protein transfer from epididymosomes to spermatozoa. Electrophoretic analysis revealed that protein composition is different from the epididymal soluble compartment as well as from similar vesicles present in the semen. Protein association with epididymosome is very strong as revealed by resistance to extraction with detergent. Matrix-assisted laser desorption ionization time-of-flight as well as immunodetection techniques have been used to identify some proteins associated to epididymosomes and spermatozoa. An aldose reductase known for its 20alpha-hydroxysteroid dehydrogenase activity and the cytokine (macrophage migration inhibitory factor) have been identified. These two proteins have been immunolocalized in principal cells of the epididymal epithelium, a more intense signal being detected in the distal epididymal segment as well as in the vas deferens. Database search revealed that these two proteins are characterized by the lack of a signal peptide. These results are discussed with regard to a possible apocrine mode of secretion of these proteins acquired by spermatozoa during the epididymal transit.     

Studies of the guinea-pig epididymis

Summary The innervation of the ductuli efferentes and seven zones of the guinea-pig epididymis was investigated using immunohistochemical, histochemical and electron-micro-scopical techniques. Nerve fibers were localized by use of antibodies against substance P (SP-IR), vasoactive intestinal polypeptide (VIP-IR) and dopamine-beta-hydroxylase (DBH-IR). In the ductuli efferentes and all zones of the epididymal duct, SP-IR is consistently observed in the interstitial tissue and perivascular areas. Histochemistry reveals a significant amount of acetylcholinesterase-containing fibers in the interstitial, perivascular and periductal smooth muscles of the ductuli efferentes and zones V, VI and VII. In contrast to the homogeneous distribution of SP-IR within all zones of the epididymis, VIP-IR is seen only in zones VI and VII. Within these zones, VIP-IR is detected in large amounts in the subepithelial and muscular layers as is a sparse number of SP-IR varicosities. DBH-IR is also seen throughout all zones in the interstitial and perivascular regions with a tendency to increase in zones VI and VII. Transmission electron microscopy (TEM) reveals evidence of a cholinergic (agranular vesicles, AGV), adrenergic (small granular vesicles, SGV) and peptidergic (large granular vesicles, LGV) innervation throughout the interstitial connective tissue of the ductuli efferentes and all epididymal zones. Furthermore AGV are localized in the subepithelial layer, and also co-stored with LGV in the muscular layer of zones VI and VII. No nerve profiles were encountered within the epithelium.Correlation of immunohistochemical findings to TEM counterparts as well as their possible functional role are discussed.Supported by the Deutsche Forschungsgemeinschaft     

Morphology and developmental competence of bovine oocytes relative to follicular status

In cattle, follicle dimension has been used as the main criterion for selection of oocytes for in vitro embryo production. However, follicles with similar diameters may be in very different physiologic phases. The aim of this study was to investigate whether morphology and developmental competence of cumulus-oocyte complexes (COCs) are related to the phase of development of the follicle, and presence of the corpus luteum (CL) or the dominant follicle in the ovary from which the COCs were collected. Cows (n = 143) were given a luteolytic dose of PGF(2alpha) and 8 days later underwent transvaginal ultrasound guided ablation of follicles > or =4mm to induce emergence of a new follicular wave. Cows (n = 10-20 per replicate) were slaughtered on Day 2, 3, 5 or 7 (Day 0 = follicular wave emergence), equivalent to the growing, early static, late static, and regressing phases of subordinate follicle development. COCs were collected from subordinate follicles > or =3mm, were classified as denuded, degenerated or healthy, and underwent IVM-IVF-IVC. The proportion of oocytes that developed to the blastocyst stage was higher (P<0.05) in those collected on Day 5 after wave emergence (23%) than on Day 2 (12%), 3 (13%) or 7 (16%). Data did not support the hypothesis of a local effect of the CL or dominant follicle. We conclude that a positive relationship exists between early follicular regression and oocyte competence. Moreover, morphologic characteristics of oocyte quality used in this study were not predictive in identifying competent oocytes.