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.

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.

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.

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.

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.