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Y Z Abdelbaki

Publications and source records attributed to Y Z Abdelbaki.

14 recordsLinked to original sources
PubMed1986

Microanatomy of the renicule of Balaena mysticetus.

Renicules from twelve bowhead whales (Balaena mysticetus) were examined utilizing light, scanning electron, and transmission electron microscopes. The basic organization of the renicule into capsule, cortex, sporta perimedullaris, medulla, and calyx is described. Despite less than perfect preservation resulting from environmental and logistical conditions at the collecting sites, it has been possible to document the basic microstructure of most components of the renicule of this endangered species. Several unusual features were observed. The absence of smooth muscle fibers (other than in vessel walls) from the capsule, sporta perimedullaris, and calyx wall is a departure from what is reported in other cetaceans as is the consistent presence of arcuate arteries in the substance of the sporta perimedullaris. Large subcapsular veins are present but do not appear to represent connecting elements in an alternative venous return through capsular and interrenicular veins. Elastic fibers are seen only in the sporta perimedullaris and the calyx wall, whereas reticular fibers are most abundant in the medullary stroma. Finally, enlarged cells with clear cytoplasm are seen in the tunica media of the glomerular afferent arterioles extending a variable, but always considerable, distance toward the interlobular arteriole. These cells are presumed to represent an extended array of the epithelioid cells common in the afferent arterioles of the juxtaglomerular apparatus of other mammalian kidneys.

Animals↗
PubMed1986

Comparative morphology of esophageal mucosa and submucosa in dogs from 1 to 337 days of age.

Scanning electron microscopy, light microscopy, and morphometric analyses were used to examine the morphology of the tunica mucosa-tela submucosa of the cervical, thoracic, and abdominal parts of the esophagus of healthy dogs from birth to 337 days of age from 3 litters of dogs whelped and reared under controlled conditions. Apart from the absence of a lamina muscularis mucosae from the cervical part of the esophagus of all dogs examined, little regional variation was detected. However, morphologic variation associated with age was observed. The number and complexity of microplicae on surface epithelial cells, as observed with the scanning electron microscope, increased with age, particularly between 1-day-old and 21-day-old dogs. Although scanning electron microscopy revealed typical duct openings from the submucosal glands in 1-day-old dogs, light microscopy revealed few functional glands. These glands gradually developed into a complex strata of tubules and acini during the time that secretory activity and the volume fraction of the tunica mucosa-tela submucosa occupied by glands increased with age. The presence of ciliated cells in the esophagus of 1-day-old dogs was apparent with scanning electron and light microscopes. Ciliated cells were always most abundant in the abdominal part of the esophagus. Finally, morphometric analyses revealed a significant increase in epithelial and connective tissue compartment thicknesses, as well as a marked increase in the volume fraction occupied by glands between 1 day and 161 days after dogs were whelped. A smaller decrease in all 3 measures occurred between 161 and 337 days after the dogs were whelped.

Aging↗
PubMed1985

Epidermal and papillary dermal characteristics of the bowhead whale (Balaena mysticetus).

Skin samples from most body regions of the bowhead whale were examined. The epidermis is 2.7 to 50 times thicker than that reported in other cetaceans with both regional and individual variations in thickness. The thinnest areas examined (1 mm) occur on the eyelid margins and the thickest (25 mm) occur on the lower jaw. A distinctive parakeratotic stratum corneum with a thick underlying stratum spinosum (without a stratum granulosum) extends over the entire body surface. From a few dozen to several hundred epidermal lesions are present on all whales studied. A typical stratum basale of germinative keratinocytes (with melanocytes in pigmented areas) rests upon a well-defined basal lamina. Epidermal rod arrays arise from the basal keratinocytes which cover highly elongated dermal papillae and extend to the epidermal surface through the distal stratum spinosum and the stratum corneum. At least four diatom genera occur on and in the stratum corneum and lesion areas of different whales. The superficial dermis consists of a papillary layer with long (up to 13 mm) dermal papillae interdigitating with the epidermis from a basal area that is 2-4 mm in thickness. The number of dermal papillae per mm2 varies inversely with the thickness of the epidermis. Large diameter, sensory papillae packed with tortuous, highly elongated, encapsulated nerve end organs also interdigitate with the thin epidermal areas of the ventral surface of the rostrum, the upper and lower lip margins, and the upper and lower eyelid margins. Scattered, single, stiff hairs emerge from the skin only in specific, pigmented regions of the head.

Animals↗
PubMed1984

Macroanatomy of the renicule of the bowhead whale (Balaena mysticetus).

The macroanatomy of renicules and surrounding tissues from the kidneys of five Eskimo-harvested bowhead whales, Balaena mysticetus , was examined. These renicules are similar in overall structure to those of other cetaceans and intermediate in size. There are several important differences including the presence of arcuate vessels within the sporta perimedullaris , the extension of connective tissue from the sporta deep into the peripheral cortex, and the presence of very large, thin-walled veins that occupy the interrenicular spaces. Arterial and venous plexuses outside the substance of the sporta reported in other cetaceans were not observed in the bowhead .

Animals↗
PubMed1984

Microanatomy of the major airway mucosa of the bowhead whale, Balaena mysticetus.

In the bowhead whale, Balaena mysticetus, the mucosa of the major airways from the blowholes through the rostral portion of the larynx is lined with parakeratotic, pigmented, stratified squamous epithelium. Scattered enlarged connective tissue papillae of the lamina propria of the nasal vestibules and the palatopharyngeal sphincter contain encapsulated nerve endings. Abundant papillae in the mucosa covering the epiglottic and arytenoid cartilages contain similar nerve endings. The remainder of the laryngeal cavity and laryngeal sac is lined by a variably pigmented, stratified squamous epithelium, which is not keratinized. At the laryngotracheal junction the lining changes to ciliated pseudostratified columnar epithelium which continues through the trachea and principal bronchi. Scanning electron microscopy (SEM) indicates that this epithelium is typically mammalian, with approximately half of the surface cells bearing cilia and slender microvilli. The remaining cells are mucus producing and have thicker microvilli. The valvular mass regulating the external nares consists of irregular, dense white fibrous connective tissue with numerous adipose cells and is penetrated by skeletal muscle cords ranging from 2-4 mm in diameter. The septal mass between the blowholes is composed of irregular, dense white fibrous connective tissue containing large tendinous bundles, clusters of adipose cells, and several large arteries and thick-walled veins. The lamina propria of the nasal vestibules is irregular, dense white fibrous connective tissue. That of the larynx is not as dense and contains proportionately more elastic fibers. The laryngeal sac does not contain elastic laminae, but does have a tunica muscularis of skeletal muscle bundles. Within the trachea and principal bronchi, the lamina propria possesses laminae of longitudinally oriented elastic fibers and simple, branched tubuloalveolar mucous glands. The nasal, laryngeal, tracheal, and bronchial cartilages are hyaline with vascular channels.

Animals↗
PubMed1983

Gross anatomy of the respiratory system of the bowhead whale, Balaena mysticetus.

Components of the respiratory system from seven bowhead whales have been examined. The paired and laterally curved external nares are passively closed by a valve-like mass located in the rostral, lateral, and ventral walls of the nasal vestibules. Nasal septal cartilages are paired smooth plates rostrally changing to accordion-like folds caudally. The epiglottic and arytenoidal protuberances of the larynx are typically cetacean, but blunt. The cricoid cartilage is not a complete ring, but an elongated, inverted, trough-shaped structure. The thyroid cartilage is trough-shaped with elongated cranial cornua curving dorsocaudally from each thyroid lamina. A conical mass of skeletal muscle serves as the floor of the short trachea and also surrounds the termination of the laryngeal sac. The trachea is dorsoventrally compressed, lacks a tracheal bronchus, and its width equals its length. The principal bronchi give rise to lobar bronchi at obtuse angles. Large segmental bronchi branch extensively from lobar bronchi near the mediastinal lung surface. The lungs are rectangular and of nearly uniform thickness throughout, without external or internal lobulation.

Animals↗
PubMed1982

Scanning electron microscopic study of the small intestine of dogs from birth to 337 days of age.

The surface morphology of the small intestine of dogs from birth to 337 days of age was studied by scanning electron microscopy. The small intestinal surface morphology was similar to that described for other species, except for irregular villous length in the duodenum, jejunum, and ileum of the dog from birth to 21 days of age. The absorptive epithelial cells and goblet cells were similar in morphology and distribution from birth to 337 days. Segmented filamentous bacteria were attached to the ileal mucosa of dogs 54 to 161 days of age.

Animals↗
PubMed1976

Nephrotoxic action of rattlesnake and sea snake venoms: an electron-microscopic study.

The fine structure of renal corpuscles and proximal convoluted tubules of the right kidneys of Suiss mice were studied 9 hr after the injection of the venom of Crotalus atrox (Western diamond-back rattlesnake) or the venom of Laticauda semifasciata (broad-banded blue sea snake). Rattlesnake envenomation resulted in several ultrastructural changes in the renal corpuscles and proximal convoluted tubules. Visceral epithelial changes included intracellular oedema, blebbing, vesiculations, the formation of microvillus projections and dilatation of the endoplasmic reticulum and mitochondria. Changes in the parietal epithelium were similar except that no microvillus projections were noted. Mesangiolysis was a consistent finding. Collagenous fibrils were very prominent in the lysed areas of the mesangial cells. Increased numbers of lysosome-related structures were noted in the proximal convoluted tubule cells. Most of the nuclear cisternae of the cells of the renal corpuscles and proximal convoluted tubules were greatly dilated. Sea snake envenomation resulted in focal organellar swelling and focal intracellular oedema of the visceral epithelium. This venom did not affect the cells of the proximal convoluted tubule. The presence of light and dark visceral epithelial cells has been a consistent finding for both the control and the environmated groups.

Animals↗
PubMed1976

Variations in kidney ultrastructure with a variety of paraformaldehyde fixation techniques.

Variations in fine structure of glomeruli and proximal tubules were studied to determine the results of several fixation techniques with paraformaldehyde. Immersion fixation techniques generally resulted in poor fixation, while the quality of fixation by perfusion was directly related to the concentration of the paraformaldehyde. The best technique was fixation by perfusion and immersion in 3% paraformaldehyde for 2 h followed by a post-fixation in 1% OsO4 for 1 h. Intracellular edema was noted in all epithelial, mesangial and proximal tubular cells that were from poorly fixed kidneys. Swollen mitochondria and the dilated endoplasmic reticulum were common in many of those cells. Mesangial and proximal tubular cells were the first to swell. Poor fixation produced the early stages of autolysis. The criteria for good paraformaldehyde fixation are discussed.

Animals↗