Ultrastructural, Sensory and Functional Anatomy of the Northern Elephant Seal (Mirounga angustirostris) Facial Vibrissae.

Vibrissae (whiskers) play a key role in underwater orientation in foraging phocids through vibrotactile sensation processing. Our aim was to evaluate the structure of northern elephant seal (NES) vibrissae by means of light (LM) and transmission electron microscopy (TEM), in order to elucidate their function. Vibrissal follicles were processed using standardized laboratory methods and LM/TEM techniques. Individual follicular axonal numbers were counted and axonal diameter measured and averaged. NES have mystacial, rhinal, supraorbital and labial vibrissae. The vibrissal follicles are histologically subdivided into a ring, upper and lower cavernous sinuses (LCS). Each vibrissa is innervated by the deep vibrissal nerve. The average number of axons per large mystacial vibrissa is 1804 (±123), rhinal 985 (±241), supraorbital 1,064 (±204) and 374 (±65) in labial vibrissa. The entire vibrissal system carries an estimated 148 573 axons, and mystacial vibrissae alone have 125 323 axons. Axonal conduction velocity for each vibrissal type is 55.26 m/s for labial, 56.58 m/s for rhinal and 35.88 m/s for mystacial vibrissae. TEM and LM revealed a plethora of mechanoreceptors within the vibrissal follicles: Merkel cell-neurite complexes, lanceolate and pilo-Ruffini end organs. A vast number of sensory axons projecting from the entire vibrissal system indicate that the vibrissal sensory area takes up a large proportion of phocids' somatosensory cortex. In conclusion, NES has highly sensitive and finely tuned vibrotactile vibrissal sense organs.

Histological Characteristics of the Tracheobronchial Tree of the Least Shrew (Cryptotis Parva).

The least shrew (Cryptotis parva) is a small vomit-competent insectivorous species which has recently been introduced as an emesis animal model in the laboratory. In this study, the respiratory system of the least shrew was examined and compared with the well-established larger species routinely used in the laboratory. Five least shrews (4-5 g body weight, 45-60 days old) were used. Standard histological procedures were followed for light microscopic examination. The lining epithelium of the trachea was found to be pseudostratified ciliated columnar (PSCC). Three types of cells were easily identified, basal and ciliated as well as few goblet cells interspersed among the ciliated cells and they were not clearly recognizable. A few tracheal seromucous glands were located at the free end of the C-shaped cartilaginous rings. The cartilaginous rings are replaced by smooth muscle cells before the bronchi enter into the lung. The lining epithelium of tracheobronchial tree gradually changes into simple cuboidal epithelium that lacks goblet cells. However, the division of the tracheobronchial tree is similar to other mammalian species. On the other hand, the principal bronchus lacks cartilaginous plaques as it becomes intrapulmonary bronchus. The wall of the bronchi is supported by thick layers of spirally arranged smooth muscles. Two types of cells were readily recognizable: basal and ciliated cells, with rarely observed goblet cells. In addition, the PSCC epithelium changes into simple cuboidal much earlier in the bronchial division relative to other species.

Morphological study of the oesophagus and stomach of the Gopher snake Pituophis catenifer.

The gastrointestinal tract of the snake has various distinctions from mammals, birds and other reptiles. Five gopher snakes (Pituophis catenifer) were studied in relation to the gross anatomical measurements of visceral organs relative to body length as well as the histology of the oesophagus and the stomach. The oesophagus closely resembles the empty stomach upon gross examination. A small palpable thickening was observed at the junction of the oesophagus with the stomach. In both the oesophagus and the stomach, there were cellular and structural differences observed in the tunica mucosa which can be linked to the feeding habits and natural biology of the snake when compared to those of mammals. Both oesophagus and stomach were lined by simple columnar to pseudostratified columnar epithelium. There were no glands in the wall of the oesophagus. Scattered ciliated triangular cells (brush cells) were present among the columnar epithelial cells in the distal portion of the oesophagus. The stomach can be divided into three portions (proximal, middle and distal). The stomach has a small non-glandular portion with low folds. After this small non-glandular portion, glands started to appear and gradually increase in quantity. The largest quantity of glands appeared in the middle portion of the stomach with more branching folds resulting in a decrease in the lumen diameter. The tunica muscularis increased in thickness at the oesophageal and the pyloric-duodenal junctions. Positive statistical correlations were established in thickness of the tunica muscularis between proximal and distal portions of the oesophagus and the stomach.

Histological assessment of selected blood vessels of the phocid seals (northern elephant and harbour seals).

Phocid seals exhibit vascular adaptations that allow them to undertake prolonged deep dives. These vascular adaptations are either unique to phocids, or are modified vascular equivalents to those present in terrestrial mammals. One such adaptation, the aortic bulb, is a spherical enlargement of the ascending aorta specific to phocid seals. Its histological make-up consists of a reinforced tunica media with circular and longitudinal layers of elastic fibres. This reinforcement enables multi-axial deformation of the aortic bulb, thus complementing its function as a prominent elastic reservoir or 'windkessel'. A second adaptation, the hepatic sinus, is an asymmetrical dilation of the abdominal portion of the caudal vena cava and accompanying hepatic veins. The hepatic sinus is comprised of a relatively thin tunica media, with a scant smooth muscle component. The bulk of the sinus wall is comprised of tunica adventitia. A third vascular adaptation distinctive to the phocids is the pericardial venous plexus, composed of convoluted veins circumnavigating the perimeter of the heart. Microscopically, these veins have a thick tunica media and also contain valves. Smaller arteries, venules and distinct capillary beds are observed interspersed in-between these veins. It can be hypothesized, that in seals, certain vascular embryonic development may be arrested at an earlier embryonic stage, resulting in these unusual vascular formations. These modifications play a vital role in blood pressure regulation and distribution of oxygenated blood during prolonged deep diving. The purpose of this work was to elucidate the histological aspects of these unique vascular modifications and relate them to specific function.

Evaluation of the toxic potentials of cypermethrin pesticide on some reproductive and fertility parameters in the male rats.

Adult male Sprague-Dawley rats were exposed to tap water containing 0, 8,571, 17,143, or 34,286 ppm cypermethrin for 12 weeks. Based on water consumption per animal per day the rats received 13.15, 18.93, and 39.66 mg cypermethrin, respectively. Fertility was significantly reduced in male rats ingesting cypermethrin at a concentration of 13.15 and 18.93 mg in that the number of females impregnated by them was significantly reduced. The number of implantation sites was significantly reduced in females mated with males that had ingested cypermethrin at a concentration of 39.66 mg. A significant reduction in the number of viable fetuses was observed in females impregnated by the exposed males at all three doses of cypermethrin. The body weight gain was significantly lower in the treated males. Ingestion of cypermethrin at a concentration of 18.93 or 39.66 mg per day resulted in a significant increase in the weights of testes and seminal vesicles. Preputial gland weights were increased at all three concentrations of cypermethrin. Epididymal and testicular sperm counts as well as daily sperm production were significantly decreased in exposed males. The serum levels of testosterone, follicle-stimulating hormone and luteinizing hormone were significantly reduced in males exposed to 39.66 mg per day. Ingestion of cypermethrin at 18.93 and 39.66 mg/animal/day also resulted in a significant decrease in the perimeter and number of cell layers of the seminiferous tubules. The testes of treated animals were infiltrated with congested blood vessels with marked hemorrhage and a significant accumulation of connective tissue surrounding the seminiferous tubules, which contained a large number of immature spermatids. These results clearly demonstrate the adverse effects of cypermethrin pesticide on fertility and reproduction in male rats.

Activin-A differentially regulates steroidogenesis by sheep granulosa cells.

Intra-ovarian factors, such as activin, are implicated in multiple aspects of follicular development in mammalian ovaries. This study was conducted to investigate a possible effect of activin-A on steroidogenesis in sheep granulosa cells in vitro. Sheep granulosa cells were obtained from medium antral follicles and cultured in a chemically defined RPMI -1640. Oestradiol and progesterone production, secreted by the cultured cells, was evaluated by enzyme-linked immunosorbent assay. In order to determine the dose effect of activin-A on steroidogenesis, granulosa cells were cultured in the presence of increasing concentrations of activin-A (0, 0.5, 5 and 50 ng ml(-1)) for 48 hours. The results revealed that activin-A exerts a differential effect on steroidogenesis in granulosa cells in such a way that it significantly (P < 0.05) suppressed progesterone production and enhanced oestradiol production. These results were confirmed by the time effect of activin-A on oestradiol and progesterone production in granulosa cells. In the absence of activin-A treatment, granulosa cells showed enhanced capacity to produce progesterone, but not oestradiol, as the time progressed from 12 to 48 hours. Treatment of sheep granulosa cells with 25 ng ml(-1)activin-A for 12, 24 and 48 hours significantly stimulated oestradiol production but inhibited progesterone production. These results suggest that activin-A is a local regulator of sheep folliculogenesis that might act to support differentiation in granulosa cells and suppress luteinisation.

Alkaline phosphatase and 5'-nucleotidase enzymes in the carotid rete-cavernous sinus complex of sheep and goats.

12 sheep and 4 goats were used to detect the presence of alkaline phosphatase (A.P.) and 5'-nucleotidase (5'-N) enzymes in the carotid rete-cavernous sinus structure. Different methods of preservation were used. The calcium and the lead methods were used to detect the presence of A.P. and 5'-N, respectively. Best results in their detection were obtained with liquid nitrogen preservation. A.P. enzyme was found in and around areas in which blood capillaries were present, indicating active transport of materials through the capillary membrane. Slight enzymatic activity was seen on the endothelial surface of the rete branches, while the enzyme seemed to be absent from the cavernous sinus. 5'-N was discernible in the tunica adventitia and in the endothelial cells, while the tunica media of the rete branches was apparently devoid of this enzyme. Possible role of these enzymes in the vascular wall metabolism of this structure has been discussed.

Adenosine triphosphatase activity in the carotid rete-cavernous sinus complex of sheep and goats.

The carotid rete-cavernous sinus structures of sheep and goats were frozen with liquid nitrogen or with Freon liquid spray and were cryo-sectioned at -20 C. The main concentration of sodium- and potassium-dependent adenosine triphosphatase was on the tunica intima, especially on the endothelial cells of rete branches and the cavernous sinus. Little reaction product was discernible in the tunica media and the tunica adventitia.

Gross and scanning electron microscopy of the carotid rete--cavernous sinus complex of the sheep (Ovis aries).

Intravascularly plastic injected specimens of the carotid rete of the sheep were investigated. In addition, glutaraldehyde-fixed, freeze-fractured and sputter-coated retia were examined by SEM. The carotid rete is supplied by one caudal and 2-4 rostral rete branches of the maxillary artery, with a few variations in the origin of the rostral rete branches. The tunica adventitia of muscular arteries was continuous with that of the cavernous sinus. The endothelial cells of the cavernous sinus were differently oriented than those of the arterial rete branches. In addition, craters were found in the endothelial cells of the arteries but not in those of the cavernous sinus.

Light microscopic study of blood vessels of the nasal cavity of the pig.

4 adult pigs were used for light microscopic studies to depict the relationship between nasal blood vessels and the surface epithelium, and to describe the histomorphology of these vessels. After giving an electric shock, animals were bled to death. Tissues were collected from three regions in the nasal cavity after splitting heads sagitally. Different types of vessels were described and a new classification was suggested. Arteries were muscular in type with, as well as without, internal elastic laminae. Thick-walled veins (characterized by smooth muscle cells in the tunica media) were present throughout the nasal cavity, while thin-walled veins or cavernous spaces were discernible only in the caudal one third of the nasal cavity. Further, arteriovenous anastomoses, epithelioid arterioles, and free smooth muscle cells in the propria submucosa were observed throughout the nasal cavity.

Histomorphologic structure of the carotid rete-cavernous sinus complex and its functional importance in sheep (Ovis aries).

Paraffin sections of the carotid rete-cavernous sinus complex of sheep were studied, using different stains. The carotid rete of sheep was composed of medium-sized arteries with smooth muscle layers that were oriented in different directions. The carotid body cells may have migrated proximally in the adventitia of the intracranial portion of the internal carotid artery as its extracranial portion degenerates early in life. The cavernous sinus shared a common tunica adventitia with surrounding rete branches. At places, the wall of the cavernous sinus had a distinct tunica media interposed between the endothelial cells and the tunica adventitia. Therefore, the name cavernous venous plexus has been proposed for the cavernous sinus in sheep.

Blood supply to the nasal cavity of sheep (Ovis aries) and its significance to brain temperature regulation.

Blood supply to the nasal cavity of the sheep has been grossly studied on 25 specimens by employing different injection techniques. Following intramuscular injection of Rompun solution (Xylazine hydrochloride, 10 mg/lb body weight), the animals were killed either by bleeding or decapitation. Subsequently, the heads were perfused with physiologic saline solution, injected with various intravascular materials, and then either routinely dissected or macerated to trace the vessels. The nasal cavity of the sheep was mainly supplied by the sphenopalatine and ethmoidal, and indirectly by their anastomoses with the infraorbital, malar, major palatine, and the superior labial arteries. The venous drainage of the nasal cavity has connections with the cavernous sinus via: 1. the dorsal and/or the lateral nasal veins-angularis oculi vein-ophthalmic plexus; and 2. via the sphenopalatine vein-rostral branch of the deep facial-pterygoid plexus. The former venous pathway has also been confirmed by venography in one live anesthetized sheep. The internal carotid rete was found to be enmeshed in a venous plexus of the cavernous sinus. From their close relationship it may be inferred that their function is to accommodate flow in opposite directions and that such an arrangement has the necessary anatomic requirements expected of a countercurrent heat exchanger.

Histomorphologic studies of the nasal cavity of sheep (Ovis aries) and its significance in temperature regulation of the brain.

10 sheep were used for light microscopic studies to described the distributions of the blood vessels, epithelium, and glands of the nasal cavity. The animals were killed following intramuscular injection of Rompun solution (xylazine hydrochloride). The heads were sawed and tissues were taken from the alar fold, respiratory, and olfactory regions. More vascularity was noticed in areas of the nasal cavity that were in direct contact with the airstream. Moreover, in the submucosa, the presence of arteriovenous anastomoses, collagen fibers, elastic fibers, thick-walked or cushion veins, and free smooth muscle cells were observed, gradually decreasing from the rostral to caudal regions. The tunica media of the arteries was very thin in the vestibular region and relatively thicker in the respiratory region. On the other hand, luminal diameters of the arteries were very small in the respiratory region and relatively larger in the vestibular region. In addition, a large number of intraarterial bolsters was present in the respiratory region, but there were fewer in the olfactory region, and they occurred with still less frequency in the vestibular region.