Clinical Anatomy of the European Hamster 
men, 1953), guinea pigs (Kelemen, 1950) and rab- 
bits (Kelemen, 1955). The ectoturbinals are 
situated ventral and caudal to the folds of the endo- 
turbinals. Both groups represent true independent 
turbinals, as each arises separately from the wall of 
the ethmoid bone with an individual base. 
The architecture of the turbinals is best seen in 
serial section. The basal lamella of the first endo- 
turbinal (Fig. 2-16) is divided into two parts dis- 
tally, each forming a spiral. Caudally (Fig. 2-17), 
only the dorsal spiral is present. The second endo- 
turbinal (Figs. 2-16 to 2-19) is separated from the 
first and the third by separate meatuses. Rostrally 
(Figs. 2-16, 2-17) the second endoturbinal consists 
of only a tuberosity which broadens near the nasal 
septum. Caudally (Fig. 2-18) it bifurcates into two 
broad terminal parts. The third endoturbinal (Figs. 
2-16 to 2-19) is longer and broader than the first 
and second ones. While the fourth endoturbinal 
bends only slightly dorsally and laterally, the third 
endoturbinal bends strongly dorsolaterally (espe- 
cially prominent in Figs. 2-17 and 2-18); in this 
way, a semicircle is formed which is distinctly 
isolated from the nasal cavity. 
The three ectoturbinals (Figs. 2-16, 2-17) are 
smaller than the endoturbinals; they are enclosed 
by the first and second endoturbinals, the cribri- 
form plate (lamina cribrosa) of the ethmoid bone 
and the medial wall of the maxillary sinus. The 
first ectoturbinal (Figs. 2-16, 2-17) extends ven- 
trally from the roof of the nasal cavity, recurving 
mediodorsally. Cranially the second ectoturbinal 
projects mediodorsally without curling (Figs. 2-16, 
2-17); caudally however, it rolls ventrolaterally 
forming a small recess (Fig. 2-18). The third ecto- 
turbinal (Figs. 2-16, 2-17), the smallest of all the 
turbinals, projects vertically from the medial wall 
of the maxillary sinus, nearly touching the second 
ectoturbinal. 
The nasal conchae define three nasal passages or 
meatuses (Figs. 2-3, 2-4, 2-11 to 2-14, 2-38). 
The dorsal nasal meatus {meatus nasi dorsalis) 
(Fig. 2-13) lies between the dorsal wall of the nasal 
cavity and the dorsal nasal concha. The limits of the 
dorsal meatus include the dorsal concha, the nasal 
septum and the dorsal wall of the nasal cavity. 
Caudally, it narrows and ends at the cribriform 
plate of the ethmoid bone. The middle nasal meatus 
{meatus nasi medius) (Fig. 2-13) is located between 
the dorsal nasal concha and the ventral nasal 
concha and is a narrow fissure which joins the dor- 
sal meatus along the rostral edge of the endotur- 
binals and ends shortly thereafter. The ventral 
nasal meatus {meatus nasi ventralis) (Fig. 2-13), 
which is the continuation of the nostril, lies between 
the ventral nasal concha and the base of the nasal 
cavity. The middle and ventral conchae and mea- 
tuses comprise the respiratory portion of the nasal 
cavity, since they converge at the caudal end of the 
conchae and continue as a single median passage, 
the ventral meatus (formerly the nasopharyngeal 
duct) ventral to the endoturbinals, (Figs. 2-3 to 
2-5, 2-16 to 2-26, 2-31 to 2-37, 2-38). The endo- 
turbinals are thus supplied with air via all three 
nasal meatuses (Fig. 2-39). In passing the endo- 
turbinals, the ventral meatus gradually turns ven- 
trally, not continuing in the straight caudal direction 
typical of the Syrian golden hamster (Schwarze and 
Michel, 1959-60). 
2.4 NASOPHARYNX 
The nasal cavity passes caudally into the naso- 
pharynx {pharynx, pars nasalis) at the level of the 
soft palate, by means of the internal nostril or 
choana (Fig. 2-3). The choana is bordered laterally 
and ventrally by the palatine, and dorsally by the 
vomer and presphenoid {os praesphenoidale) bones 
(Fig. 2-8). The nasopharynx stretches 1 .5 to 1 .8 cm 
from the choana to the epiglottis, and varies in 
width from 1.5 to 3.0 mm (Figs. 2-16 to 2-26, 
2-31 to 2-37) (Jensen, 1977). 
It is lined for most of its length by respiratory epithelium, but 
caudally the ventral portion is protected with multilayered unkeratin- 
ized squamous epithelium, which becomes keratinized lateral to the 
epiglottis. 
Lateral to the epiglottis, the tiny Eustachian tube 
{tuba auditiva) establishes communication between 
the nasopharynx and the auditory bulla {bulla tym- 
panica). The tube measures 2 mm in length and 
0.25 mm in diameter (Jensen, 1917). 
It is lined with respiratory epithelium, and is supported by hyaline 
cartilage 
2.5 VOMERONASAL ORGANS 
Paired vomeronasal organs {organum vomero- 
nasale) are situated at the ventral margin of the 
18 
