Koei Ojima

Suppressive effect of vagal afferents on the activity of the trigeminal spinal neurons related to the jaw-opening reflex in rats : Involvement of the endogenous opioid system

The purpose of the present study is to test the hypothesis that via the endogenous pain control system, vagal afferent input modulates the activity of the trigeminal spinal nucleus oralis (TSNO) related to the tooth pulp (TP)-evoked jaw-opening reflex (JOR). Extracellular single-unit recordings were made from 36 TSNO units responding to TP electrical stimulation with a constant temporal relationship to a digastric electromyogram (dEMG) signal in 26 pentobarbital-anesthetized rats. The activity of 36 TSNO neurons and the amplitude of the dEMG increased proportionally during 1.0-3.5 times the threshold for JOR. Some of these neurons (4 out of 5) were also excited by chemical stimulation (bradykinin, 1-2 microl, 1 mM) of TP. In 31 out of 36 TSNO neurons (86%), their activities during tooth pulp stimulation were suppressed by conditioning stimulation of the right vagus nerve. The suppressive effect of vagal afferent stimulation occurred at conditioning-test intervals of 20-150 ms after the onset of the stimulation, and its maximal suppressive effect occurred at approximately 50 ms. The mean time course of this suppressive effect paralleled that of the dEMG. After administration of naloxone (0.5 and 1.0 mg/kg, i.v.), an opiate receptor blocker, the suppressive effect on the activity of TSNO neurons (6 out of 8) was significantly attenuated at the conditioning-test interval of 50 ms compared to the control (p < 0.01). These results suggested that vagal afferent input inhibits nociceptive transmission in the TSNO related to TP-evoked JOR and this inhibitory effect may occur via the endogenous opioid system in rats.

Angioarchitectural comparison of the filiform papillae of the cat and rabbit using scanning electron microscopic specimens

The functional and morphological characteristics of the fungiform papillae (FuP) on the anterior dorsal surface of the cat and rabbit tongues were studied and compared using a scanning electron microscope (SEM), because the comparison of the functional and morphological relationship of FuP in microvascular cast specimens (MVCS) between these tongues is as yet not clear. In both species, FuP were found to be distributed sporadically among the numerous filiform papillae (FiP). In the cat, in particular, FuP were classified into four types (FuP I-IV) according to the shape and size of a main process (MP) and the number of accessory processes (AP). Each FuP, (FuP I-III lay along oblique lines of FiPs) contained a MP and many APs lying at the anterior basal margin of the MP, whereas FuP IV contained only the small fishnet-ball-shaped MP. In the rabbit, however, only the similar size and shape of the capillary loops, resembling the carnation flower, were scattered among FiPs on the anterior dorsal surface of the fore-tongue. These results suggest that in comparing the functional sense mechanism in both species, the FuP of the rabbit tend to be more simple than those of the cat in respect to taste sense.

The distributive pattern form and function seen in microvascular cast specimens of filiform papillae on the anterodorsal surface of the adult rat tongue

The purpose of the present study was to examine in detail the distributive pattern, form and function of small conical papillae (SCP) and of filiform papillae (FIP) in the anterodorsal part of the adult rat fore-tongue in a microvascular cast specimen (MVCS), with the scanning electron microscope (SEM), and to elucidate the close relationship between the morphological characteristics and the function of the tongue. From the results obtained in this study, SCP in the anterior part were subdivided into three types: SCP type I, II and III according to the shape, size, distributive pattern and form taken from the two peripheral sides as for as the median sulcus (MS) in the central portion. The results we obtained suggested that the primary role of SCP types I and II at the apex may be mainly that of touch and attachment to the food and water, while SCP types II and III in the anterior part function efficiently by taking the food and water from both peripheral sides to the MS or central portion, and finally transporting it into the oral cavity and supporting the mastication system.

ANGIOARCHITECTURAL CLASSIFICATION OF THE FUNGIFORM PAPILLAE IN THE CAT TONGUE

Abstract Three-dimensional structures of the microvascular network of the fungiform papillae (FuP) of the cat tongue were observed by the corrosion cast method under a scanning electron microscope (SEM). FuP were found to be distributed sporadically among the different types of numerous filiform papillae (FiP). A single FuP consisted of the main process (MP) and the accessory process (AP) which were arranged at the anterior basal margin of the MP. FuP can be classified into four types (I∼IV) according to the shape and size of the MP and the number of AP within each FuP. FuP-I to FuP-III contained a large, medium and small MP, showing the small fishnet-ball and oval-ball shapes, and these were surrounded at the anterior basal margin by AP inclining toward the anterior part of the tongue. FuP-IV contained only the small fishnet-ball-shaped MP.

Angioarchitectural structure of the fungiform papillae on rabbit tongue anterodorsal surface

The relationships between the functional and morphological characteristics and the positional difference of the microvascular cast specimen (MVCS) of the fungiform papillae (FuP) on the antero-dorsal surface of the rabbit tongue were examined and compared using a scanning electron microscope (SEM). The sporadic FuPs scattered among the numerous small filiform papillae (SfP) were found to be distributed irregularly over the antero-dorsal surface. FuPs consisted of the ascending and descending capillary loops, forming margins of the central opening at the top of FuP. They resembled flower-like configurations (carnations), the petals of which ranged from eight to twelve, and they were larger in width and more complex in shape than SfPs with morphological differences. FuPs can be classified into three types: type I (consisting of eight petals), type II (ten petals), type III (twelve petals) according to the shape of FuP, and to the petal number of the flower-like aspect on the eight points of MVCS of FuPs observed by SEM. These results suggest that the petals of the ascending and descending capillary loops of FuP expanded the flower-like figure, increased in the surface areas and effectively play a role in receiving the sense of taste.

Functional role and angioarchitectural arrangement of the filiform and fungiform papillae on the medial-dorsal surface of the beagle dog tongue.

A scanning electron microscopic study has been performed on the three-dimensional morphological structure and functional arrangement in microvascular cast specimens (MVCS) of the filiform (FiP) and fungiform papillae (FuP) of the entire medial-dorsal surface of the caudal portion of the beagle dog tongue. The characteristics and functional arrangements of each FiP and FuP were as follows: The FiPs densely and geometrically covered the entire medial-dorsal surface. The outer structure of the FiPs was composed of both the main process (mp) and accessory process (ap). These were formed by both the ascending and descending branches and originating in their tributaries was a spoon-like capillary micronetwork structure with a sharp arrowhead-like top. The mp inclined posteriorly and the ap anteriorly. On the other hand, the outer structure of the FuPs was a rounded papillary body composed of a capillary microvascular network consisting of the ascending and descending branches just as the FiPs. They were distributed sporadically along the oblique eines of FiPs in a V running from both peripheral edges in the posterocentral direction. It has been conjectured that the FiPs play a concentric functionally important role in transporting food and liquid from both the peripheral edges to the postero-central part or towards the pharynx, and on the other hand the FuPs play an assisting role in receiving gustatory sensations from the masticated food and liquid on the medial-peripheral and central-dorsal surface of the caudal portion of the beagle dog tongue.

Functional and morphological observations on the microvascular structure of the filiform and fungiform papillae in the cat tongue

The purpose of this study was to undertake a three-dimensional comparative observation of the microvascular cast specimen (MVCS) of the filiform papillae (FiP) and fungiform papillae (FuP) on the dorsal surface of the cat tongue. By means of the corrosive resin casting technique, the MVCS of the FiP and FuP of the cat tongue were prepared and examined in detail under the scanning electron microscope (SEM). The numerous FiP and FuP distributed sporadically among the different types of the FiP were found on the entire dorsal surface of each cat tongue. A single FiP consisted of a main process (MP) which contained a large spoon-shaped concave network process and the accessory process (AP) contained a bundle of spine-like processes, arranged in a circle at the basal margin of the MP. The FiP can be classified into five types (Type I-V) according to the shape and size of the MP and numbers of the AP. Each FuP consisted of a single MP which contained an ovoid head and many AP surrounding the basal margin of the MP. The FuP can be classified into four types (FuP I-IV) according to the shape and size of the MP and numbers of the AP. The MP of the FuP, a sense organ for taste, of the cat tongue was considered to be a transformed type from the MP of the FiP, which acquires the ability to masticate and swallow functionally.

Angioarchitectural structure of the fungiform papillae on the anterodorsal surface of the rat tongue

To ascertain whether the microvascular morphological differences of fungiform papillae (FuP) on the anterodorsal surface of the rat tongue are locationally and functionally related, this study aimed at examining and comparing, in greater detail, the comparative morphological characteristics of FuP. FuP were sporadically and consistently scattered among numerous filiform papillae (FiP) in three parts: the apical, central and in front of the intermolar eminence on the anterodorsal surface. We studied these by means of the microvascular cast specimen (MVCS) of FuP using scanning electron microscopy (SEM). The results obtained in this study showed that in all three parts on the anterodorsal region, the capillary bed of FuP presented as a netbasket-like and cylindrical figure with a central hole consisting of 4-5 horizontal rings of several ascending and descending roots. FuP in the central part on the anterodorsal region were relatively larger in size and more cylindrical in shape than those of both the other parts, and they play the leading part as sensory organs for the taste sense and were regarded as taste receptive organs.

Numerical variation and distributive pattern on micro vascular cast specimens of vallate papillae in the crossbred Japanese cat tongue

In order to examine in detail the numerical variation and distributive pattern of vallate papillae (VaP) on the lingual posterior dorsal surface of the crossbred Japanese cat tongue, macroscopic, stereoscopic and scanning electron microscopic studies by means of a microvascular cast specimen (MVCS) were carried out under the scanning electron microscope (SEM). Regardless of sex, there were 4-8 VaPs in number, with an average of 6, forming 2-4 pairs arranged by type which could be observed symmetrically or asymmetrically on both sides of the posterior dorsal region of the tongue surface. The results of this study showed that the distributive pattern of VaP can be classified into six forms: typical forms I (2 left and 2 right), II (3:3) and III (4:4); and forms IV (2:3), V (2:4) and VI (3:2) were atypical. It seems that there is every probability that statistically another atypical form (3:4), (4:2), (4:3) will appear in the future. Nevertheless, in a large number of studies on the lingual papillae of the cat tongue, 8 VaPs arranged in pairs by type have been found (form III (4:4)) has not yet been reported in the crossbred Japanese cat tongue.

Functional role of V form distribution seen in microvascular cast specimens of the filiform and fungiform papillae on the posterior central dorsal surface of the cat tongue

The relationship between the functional role and three-dimensional structures of the microvascular network of the filiform papillae (FiP) and fungiform papillae (FuP) on the posterior central surface of the cat tongue were observed by the corrosion cast method under a scanning electron microscope (SEM). FiP can be classified into five types; types I-V (Ojima and Lowe 1995), and FuP, found to be distributed sporadically among FiP (I-V), into four types; types I-IV (Ojima et al. 1996 b) according to the shape and size of the main process (MP) and the number of the accessory processes (AP). Each of the types I-V of FiP were arranged in the form of a V as oblique lines running in an orderly and geometrical fashion from the posterior central zone to the anterior peripheral zone in both directions. Each of the types I-IV of FuP were scattered throughout the line of FiPs arranged in the form of a V, the point of which is directed towards the pharynx. FiPs play an important role in the drinking of milk and water, holding, masticating and swallowing the food and, after mixing the food with saliva, in the transporting of the food mass towards the pharynx. The MP of FuPs is considered to be a modified form of the MP of FiP of the cat tongue function (Ojima et al. 1996 c) as part of a sense organ for taste.