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Biomedical subjects

W H Boyd

Publications and source records attributed to W H Boyd.

At least 37 records · Page 2Linked to original sources
PubMed1983

Bovine pituitary intraglandular colloid: a transport medium.

Bovine pituitary intraglandular colloid is formed by the cyclic degeneration of marginal cells lining the intermediate lobe and is housed in the intraglandular lumen (residual lumen). The lumen communicates with the subarachnoid cerebrospinal fluid space by well defined channels. Electrophoresis in acrylamide gel shows bovine pituitary intraglandular colloid as having double protein bands identical to the protein in bovine and human cerebrospinal fluid. These studies demonstrate two distinct bands in the gamma region for colloid, not apparent in the normal bovine or human cerebrospinal fluid due to the low concentration of gamma globulins. We conclude that pituitary colloid, laden with immunoreactive fragments of various pituitary hormones, is discharged from the hypophyseal intraglandular space, directly into the subarachnoid cerebrospinal fluid space.

Animals↗
PubMed1983

Salient characteristics of bovine pituitary intraglandular colloid: a transport medium for determinants to pituitary hormones and immunoglobulins.

Bovine hypophyseal intraglandular colloid, the holocrine secretion of marginal intermediate lobe cells, contains high molecular weight (MW 45 000 to 158 000) protein fractions and low molecular weight (MW below 25 000) peptide fractions. The fractions display immunoreactive determinants similar to those in pituitary hormones, cerebrospinal fluid (CSF), serum IgG and albumin. Immunoelectrophoresis shows that components in high molecular weight fractions distribute themselves in three distinct bands (gamma, beta, alpha), while those in low molecular weight fractions distribute themselves in two bands (gamma and alpha). Physiochemical characteristics, i.e., sedimentation rate, percentage of hexose, total CHO and 12C as well as the content of cystine are presented. It is concluded that pituitary colloid should not be dismissed as a waste product of cellular degeneration, since there are strong suggestions that it serves as a transport medium for certain pituitary hormones.

Albumins↗
PubMed1980

The relationship of intraglandular colloid production to hormone synthesis.

The production of intraglandular colloid, brought about by the cyclic breakdown of intermediate lobe cells, is related to the synthesis of hormones in the hypophysis. By analyzing the 'shift' of the amino acid, cystine, during various phases of the gland's cycle it is apparent that hormones, as well as other protein determinants of immunological importance, are transported by way of the intraglandular cleft to the venous circulation and to the cerebrospinal fluid.

Animals↗
PubMed1980

Pituitary colloid--a non vascular secretion with immunoglobulin-like properties.

We show evidence of an internal holocrine secretion capable of distributing its immunoreactive substances to the cerebrospinal fluid (CSF) and to the venous circulation of the cavernous sinuses. The substances, covering a wide molecular weight range, appear on immunoelectrophoresis, to be similar to serum proteins. Double diffusion shows no identity to serum immunoglobulins or albumin even though antisera produced against serum components react positively. Of equal interest is their identification with pituitary hormones, which theoretically are secreted directly into the blood stream. There is a suggestion that elevated or suppressed levels of immunoglobulins and other serum components manifest by current methodology may, in fact, be due to changes in pituitary function. This paper proposes that we take a serious look at the intermediate lobe of the pituitary gland, and examine its unique and individual contributions to our biological chemistry.

Animals↗
PubMed1980

Low molecular weight protein in bovine anterior pituitary similar to immunoglobulin M.

Bovine pituitary IgM was isolated from anterior lobe material by molecular sieve and DEAE-cellulose chromatography. It was characterized using physico-chemical and immunochemical techniques. The molecular weight of the molecule was below 20 000, and immunoelectrophoretic and immunodiffusion analysis, demonstrated precipitin arcs for IgM. The small molecular weight protein may prove to be significant in continuing studies of IgM and the relationship of the pituitary gland to the immune system.

Animals↗
PubMed1980

Intrinsic neuronal elements of the hypophyseal intermediate lobe.

The last neuron in the bovine hypophyseal neuroendocrine system is located in the intermediate lobe and not in the hypothalamus. Intrinsic neuronal elements, neurosensory and neurosecretory, of the intermediate lobe of the hypophysis are currently very relevant and they may be directly related to the chemically linked peptides including MSH, LPH, ACTH and the endorphins contained in the intermediate lobe. Hypothalamo-hypophyseal fibers innervating the intermediate lobe, subserve a trophic maintenance as well as a regulatory and feedback function. Variations in hypothalamic influences that tend to change the milieu interior of the intermediate lobe, activate the intrinsic neurosensory and neurosecretory elements. The neurosensory cell, an internuncial neuron, subserving a receptive function, analyzes and integrates changes in the environment of the lobe and sends either stimulatory or inhibitory impulses to the neurosecretory cell. Stimulatory impulses temporarily polarize the neurosecretory cell which eliminates specific materials that diffuse amongst intermediate lobe cells. The materials, in turn, stimulate certain intermediate lobe cells whose secretions are directed towards satisfying bodily functions as designated by the hypothalamus. The rather avascular intermediate lobe, utilizes intraglandular colloid, the holocrine secretion of the lobe, to transport its products to he cerebro-spinal fluid circulation and to the systemic venous circulation of the cavernous sinuses. When bodily functions registered by the hypothalamus (serving as a feedback organ) are satisfied, the hypothalamo-hypophyseal fibers readjust the lobe and the intrinsic elements are "turned off."

Animals↗
PubMed1979

Binding of bovine immunoglobulins to pituitary intermediate lobe cells.

Basophilic granular cells of the bovine pituitary intermediate lobe and intraglandular colloid show an affinity for immunoglobulin IgG, IgA, and IgM. The cells were identified by direct and indirect fluorescent staining methods using blocking tests as controls. It is suggested that these cells may play some role in the synthesis and release of immunoglobulins or their determinants to the intact Ig molecule.

Animals↗
PubMed1978

Morphology of certain sensory and motor endings in muscle spindles of the rabbit's diaphragm.

The morphological features of certain sensory and motor nerve endings in muscle spindles in the rabbit's diaphragm were examined using a variety of techniques employed in light microscopy. The nuclear accumulation in the equatorial region of the spindle is encased in a dense capsule penetrated by both sensory and motor fibers. The sensory fibers from a profuse internuclear network terminating in round and triangular buttons in direct contact with the sarcoplasmic membrane of the muscle fiber. Motor end plates trail and plate endings are distributed throughout the spindle save the equatorial region. Muscle spindle motor end plates typify those observed on extrafusal muscle fibers. The trail and plate endings are readily identified since the plate axons are short in length giving rise to claw and bulb type terminal. The terminals are directly applied to the muscle fiber. The elongated axon of the trail fiber terminates in either thin tapers or in brush-like constructions.

Animals↗
PubMed1978

The structure of motor end-plates in the rabbit's diaphragm.

The musculature of the diaphragm is parallely arranged and is innervated by single segmental nerves. The pattern of distribution of the phrenic nerve is specific, with the zone of branching being restricted. Teloglia, the arborization and fundamental nuclei accompany the terminal branches, and the territory of the motor unit are definable and may be used to sample the whole fiber group. The structure of motor end-plates show only slight variances from those in other muscles.

Animals↗
PubMed1978

Antigenic activity and mobility of bovine pituitary hormones.

The antigenic activity and mobility of bovine pituitary hormones; follicle stimulating hormone (FSH), growth hormone (GH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH) and melanophore stimulating hormone (MSH) were studied with the aid of agar gel diffusion and electrophoresis. MSH and ACTH were the only hormones not demonstrating antigenicity. Tests by electrophoresis showed "gamma" mobility of the pituitary hormones exhibiting antigenic activity. The observation of antigenic determinants exhibiting identity with immunoglobulins suggests that the bovine pituitary gland houses immunoglobulin molecule and the various pituitary hormones.

Adrenocorticotropic Hormone↗
PubMed1976

The role of reticulo-endothelial cells in hemopoiesis in the adult liver.

Form their sinusoidal position in the properly stimulated adult liver, the reticulo-endothelial cell invades the hepatic cords. Here, their cytoplasmic processes come in direct contact with the cytoplasm of the hepatic cells. Ferritin is transferred from cord cells to the reticulo-endothelial cell, initiating extravascular hemopoiesis. As the reticulo-endothelial cell regains an intravascular position, it takes on the characteristics of a proerythroblast. The activity described for the adult liver follows the pattern observed in the fetal liver where proerythroblasts appear within the hepatic sinusoids only after hemopoiesis is established in the adjacent extravascular hepatic cords.

Animals↗
PubMed1976

Contractile endothelial cells in terminal segments of certain hypophyseal anterior lobe veins.

A dual system of hypophyseal anterior lobe veins is suggested for bovine. One system is associated with the gland at large and utilizes the capsular plexus of veins, while the other, not utilizing the capsular plexus, is associated with the sinusoids of the hypophyseal portal veins. As they reach the capsule of the gland, those veins not utilizing the capsular plexus, are lined, at their terminal segment by endothelial cells with contractile and secretory elements. The contractile endothelial cells subserve a valve-like action on demand of glandular function.

Animals↗