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Biomedical subjects

W V Holt

Publications and source records attributed to W V Holt.

At least 55 records · Page 3Linked to original sources
PubMed1988

Hormonal and behavioural detection of oestrus in blackbuck, Antilope cervicapra, and successful artificial insemination with fresh and frozen semen.

Hormonal detection of urinary pregnanediol-3 alpha-glucuronide proved an effective method of monitoring the progress of oestrous cycles in the blackbuck; observation of sexual behaviour in a vasectomized male was, however, a more practical procedure. Good correlation was observed between the occurrence of minimal pregnanediol concentrations in females and the maximal behavioural response by the male. On the basis of intervals between periods of behaviourally detected oestrus, a mean cycle length of 16.9 days (+/- 0.62, s.e.m.) was derived from 12 cycles (4 animals). Eleven females were inseminated in this study, 8 with freshly collected semen and 3 with frozen semen; 6 calves were obtained, 1 after the use of frozen semen. Pregnancy was monitored by measurements of pregnanediol-3 alpha-glucuronide excretion and by ultrasound scanning. The mean interval between insemination and parturition was 183.3 days inclusive, ranging from 182 to 186 days.

Animals↗
PubMed1988

Ultrastructure and secretory nature of the seminal glomus in budgerigars (Melopsittacus undulatus).

The seminal glomera from captive budgerigars were dissected and prepared for ultrastructural and histochemical studies of the lining epithelia. The general structure suggested that they are formed by convolutions of the terminal portions of the ductus deferens which appear as a network of tubules. The epithelium lining the tubules was identified as pseudostratified ciliated and non-ciliated columnar epithelium. With the electron microscope it was possible to identify two different cell types in the epithelium: type 1, ciliated cells and type 2, non-ciliated epithelial cells. Light microscopy revealed periodic acid Schiff (PAS) positive material, resistant to diastase digestion in the distal parts of some of the epithelial cells, indicating its glycoprotein nature. Alcian blue/PAS staining showed mixed acidic and neutral glycoproteins. Alcian blue staining at different hydrogen ion concentrations (pH) showed that the acidic glycoprotein was of the weakly sulphated type. Periodic acid thiocarbohydrazide silver proteinase staining, at the ultrastructural level, confirmed the presence of an intracellular glycoprotein.

Animals↗
PubMed1986

Thermotropic phase transitions in the plasma membrane of ram spermatozoa.

A steady-state fluorescence polarization technique, using the membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH), showed that separately detectable transitions occurred in the regions of 17, 26 and 36 degrees C in isolated preparations of ram sperm plasma membrane. An independent technique based on the temperature-related behaviour of calcium- and magnesium-activated ATPase detected a single phase transition in the region of 24 degrees C. Modulation of ATPase by neighbouring lipid composition was inferred from findings that phospholipase A2 caused significant stimulation of the enzyme. Cholesterol-rich liposomes caused an upward shift of the phase-transition temperature from 24 degrees C to 30 degrees C, but the reasons for this are unclear. It is considered that these phase transitions may have profound effects on sperm survival and physiology, both during normal fertilization processes and in response to cryostorage.

Adenosine Triphosphatases↗
PubMed1985

Computer-assisted measurement of sperm swimming speed in human semen: correlation of results with in vitro fertilization assays.

A semiautomatic computerized technique for the measurement of sperm swimming speed is presented. The equipment is easy to use and would be suitable for routine clinical laboratories. The value of the sperm speed measurements obtained from over 100 individuals in relation to fertility has been studied by the correlation of these results with human in vitro fertilization (IVF) data and sperm penetrating capability in the zona-free hamster egg assay. The results show that sperm speed measurements correlate very well with those of the IVF, both human and hamster, and can be used successfully, in conjunction with multivariate statistical methods, to predict the outcomes of such techniques with about 75% accuracy.

Animals↗
PubMed1985

Determination of lipid composition and thermal phase transition temperature in an enriched plasma membrane fraction from ram spermatozoa.

The preparation of a purified fraction of ram sperm plasma membranes is described and validated in this paper. Lipid analyses were performed on both the membrane preparation and whole spermatozoa; the main differences were that plasma membranes showed a significantly higher cholesterol: phospholipid molar ratio and a higher sphingomyelin content than did whole spermatozoa, but a lower proportional content of phosphatidylethanolamine. Enzymic assays revealed the presence of two distinct adenosine triphosphatase (ATPases) in the membrane fraction, activated independently by calcium and sodium ions. Arrhenius plots of the calcium-stimulated ATPase activity demonstrated that a change in energy of activation occurred in the region of 23 degrees C; it is believed that this is evidence for the occurrence of a thermal phase transition in the lipid environment of the enzyme molecules.

Adenosine Triphosphatases↗
PubMed1984

Partially irreversible cold-induced lipid phase transitions in mammalian sperm plasma membrane domains: freeze-fracture study.

In an effort to investigate the nature of the cellular injury caused when mammalian spermatozoa are cooled prior to cryopreservation, the occurrence of thermal phase transitions amongs the lipid components of the sperm plasma membrane was investigated by the use of freeze-fracture electron microscopy. The mechanisms by which glycerol and egg yolk exert protective effects during semen cooling and freezing were also examined. Ram and blackbuck spermatozoa, maintained at 30 degrees C prior to fixation at this temperature, exhibited randomly distributed intramembranous particles over the acrosomal, postacrosomal, and flagellar regions of the plasma membrane. In contrast, spermatozoa fixed at 5 degrees C after slow cooling to this temperature exhibited particle clustering over the postacrosomal region of the head as well as over the tail. These effects were not influenced by the presence of egg yolk or glycerol during the cooling procedure, although these substances protected the spermatozoa against loss of motility. Particle clustering over the sperm tail, induced by the slow cooling process, was found to be only partially reversible. The extensive areas of particle-free lipid, noted to result from the cooling procedure, were absent if the spermatozoa were rewarmed to 30 degrees C; however, the original distribution of particles was not restored and numerous small particle-free domains persisted. It is proposed that this type of irreversible change within the sperm plasma membrane may contribute to the loss of motility and fertility suffered by spermatozoa after cooling and freezing. Furthermore, it is suggested that protective substances such as egg yolk may exert their effects by countering these deleterious changes, rather than by preventing their occurrence.

Acrosome↗
PubMed1984

The structure and epididymal maturation of the spermatozoon of the common marmoset (Callithrix jacchus).

Maturation of the spermatozoon of the common marmoset (Callithrix jacchus) during epididymal transit was investigated using light and electron microscopy. Except for the caudal migration of the cytoplasmic droplet there were no apparent ultrastructural modifications, although interesting morphological features of the sperm head were observed such as the substructure of the acrosome and a waist at the equatorial region. Alteration to the plasmalemma during maturation was reflected by an increasing capacity of the sperm surface to bind wheat germ agglutinin (recognising n-acetyl-d-glucosamine) but not ricin communis or concanavalin agglutinins. This change was concomitant with the development of sperm fertilising capacity in this species.

Acrosome↗
PubMed1984

Ultrastructural aspects of spermatogenesis in the common marmoset (Callithrix jacchus).

The pattern of normal spermatogenesis in the common marmoset, Callithrix jacchus, is described and a system classifying the spermatogenic cycle into nine successive stages is presented. In contrast to most previous studies of spermatogenesis, the classification system developed in this study depends more upon the recognition of characteristic cell associations rather than upon identification of particular steps of spermatid development. The structurally simple acrosome of the marmoset spermatozoon displays insufficiently clear morphological changes during spermatid elongation to allow this to be used as a key to spermatogenic classification. Ultrastructural aspects of spermatogenesis in the marmoset are also described; in general, these correspond to similar descriptions of this process in other primates.

Animals↗
PubMed1982

Epididymal origin of a coiled-tail sperm defect in a boar.

The development of a tail-coiling defect in spermatozoa from Welsh boar was studied by light and electron microscopy. The onset of tail-coiling was coincident with the passage of spermatozoa through the epididymis, since only cells isolated from regions of the duct distal to the caput epididymidis exhibited this characteristic. An intermediate form of this abnormality was detected in the proximal corpus epididymidis, where migration of the cytoplasmic droplets mainly occurred. It is suggested that defective migration of the cytoplasmic droplet might be associated with the pathogenesis of the coiled-tail defect in this animal.

Animals↗
PubMed1981

Studies of the deferent ducts from the testis of the African elephant, Loxodonta africana. III. Ultrastructure and cytochemistry of the ductuli efferentes.

The epithelium of the ductuli efferentes is composed of ciliated, principal, halo and basal cells. The supranuclear cytoplasm of ciliated cells is penetrated by particularly long cilial rootlets which are surrounded by numerous elongate mitochondria. Microtubules are arranged along the longitudinal axis of the cells. The spaces between the microvilli of principal cells form canaliculi which penetrate the apical cytoplasm and appear to be involved in endocytotic activity. The supranuclear cytoplasm contains oval mitochondria and numerous vacuoles. Both ciliated and principal cells contain poorly developed Golgi and endoplasmic reticulum, but numerous supranuclear dense bodies are usually present. Supranuclear and basal accumulations of dense bodies were identified as lipofuscin; they were the source of brown pigmentation in the proximal two thirds of the ductuli efferentes. The halo cells were probably macrophages. They occurred quite frequently and contained crescent shaped nuclei and large accumulations of lipofuscin material.

Animals↗
PubMed1980

Studies of the deferent ducts from the testis of the African elephant, Loxodonta africana. II. Histochemistry of the epididymis.

The three main segments of the elephant epididymis were examined for the occurrence, in the spermatozoa and lining epithelium, of carbohydrates, neutral lipids and phospholipids, ATPase, alkaline phosphatase, succinic dehydrogenase, glucose-6-phosphate dehydrogenase, diaphorases, hydroxysteroid dehydrogenases, acid phosphatase and non-specific esterase. The most distinct feature of the carbohydrate content of the epididymis was a layer of acidic, alcian blue-positive glycoprotein over the luminal surface of the epithelium, particularly in the terminal segment. PAS-positive, diastase-resistant inclusions were also found throughout the epdidymis. Neutral lipid occurred as droplets above and below the nucleus in the epithelium of the middle segment, and as supranuclear accumulations in the terminal segment. All the enzymes except the steroid dehydrogenases were detected in the epididymal epithelium, and all except the steroid dehydrogenases and acid phosphatase were detected in the spermatozoa. There was considerable variation in the intensity of the cytochemical reactions in the epithelium, but not in the spermatozoa, in different regions of the epididymis. In general, the enzymes involved in active transport showed strongest reactions in the initial and terminal segments, the reactions in the stereocilia being the most intense. The enzymes involved in energy metabolism showed strongest reactions in the middle and terminal segments, with the activity being fairly evenly distributed throughout the cytoplasm of the principal cells. However, the two lysosomal enzymes which were studied showed quite different distributions: the reactions for acid phosphatase were strongest in the initial and middle segments, whilst the reactions for non-specific esterase were strongest in the middle and terminal segments. It is suggested that the initial segment is involved in absorptive and anabolic activity, the middle segment in anabolic activity, and the terminal segment (where spermatozoa are stored ready for ejaculation) in considerable metabolic activity and active transport of substrates across the epithelium.

Acid Phosphatase↗
PubMed1977

Postnatal development of the testes in the cuis, Galea Musteloides.

Testicular development to 9 months of age has been studied. Seminiferous tubule diameter increased in a linear manner between 13 and 65 days of age, and there was a steep increase in testicular weight with age. At about 9 months the animals weighed 400-500 g and total testicular weight was about 10 g. This relatively large testicular size was correlated with high sperm density in the semen. Spermatogenesis commenced at about 21-25 days of age, when the first spermatids were found. Spermatozoa appeared in a small proportion of seminiferous tubules by 31-35 days of age, and were seen in the epididymides of an animal of 31 and another of 34 days. Epididymal spermatozoas were consistently present in large numbers after 60 days and this correlated with the increased frequency of mature seminiferous tubules. Leydig cell size increased rapidly from 13 to about 60 days, then remained constant. Inferences have been drawn from this and the study of spermatogenesis about the level of testosterone secretion. The results indicate that the male cuis is almost fully grown and sexually mature by about 90 days of age.

Aging↗