Clinical Anatomy of the European Hamster 
physis (Fig. 2-72) demonstrates its structure in the 
European hamster. The largest part is the adeno- 
hypophysis or anterior lobe, with its ventrally dis- 
posed distal part (pars dtstalis). The middle lobe 
(pars intermedia) is small and surrounds the neuro- 
hypophysis, or posterior lobe, ventrally and later- 
ally. Between the distal and intermediate parts of 
the adenohypophysis is the prominent interhypo- 
physeal cleft (cavum hypophysis) which extends to 
the caudal third of the hypophysis. The neuro- 
hypophysis is relatively small and lies dorsomedi- 
ally. The short, narrow, cone-shaped infundibular 
cavity (pars cava infundibuli) penetrates into the 
neurohypophysis. The details of the hypophysis of 
the European hamster are similar to those of the 
.Syrian golden hamster (.Schwarze and Michel, 
1959-60) and the Chinese hamster (Horber, et ai, 
1974) . 
The adenohypophysis contains acidophilic, basophilic and chromo- 
phobic cells in hematoxyiin-eosin stains. Each type is either loosely 
dispersed or arranged in cords surrounding sinusoids and sparse inter- 
stitial connective tissue elements. The acidophils include somatotropes, 
producing growth hormone (.STH) and mammotropes, producing 
mammotropic hormone (LTH). The basophils include the gonado- 
trophs, thyrotrophs and corticotrophs; the gonadotrophs are the source 
of the follicle-stimulating hormone (F.SH), luteinizing hormone (LH) 
and male interstitial cell-stimulating hormone (ICSH). The thyro- 
trophs produce thyroid stimulating hormone (T.SH) and the cortico- 
trophs produce adrenocorticotrophic hormone (ACTH). Chromo- 
phobe cell function is still unclarified. TTie chromophobe cell is thought 
to be either a precursor acidophil or basophil or else a mature cell with- 
out staining potential due to cytoplasmic degranulation (Herlant, 
1975) . 
Histometrical studies in the European hamster 
show variations in cell frequency, distribution and 
size of the nucleus during hibernation (Schlotter, 
1976) . Nuclear size is construed as a measure of the 
cell's functional state (Muschke, 1953) and fre- 
quency of cell type as a shift in total amount of hor- 
mones secreted. In females the basophils were most 
active in May and in non-hibernating animals in 
January. In males the highest activity was also in 
May but, in contrast to the female, the January 
values in nonhibernating animals were signifi- 
cantly lower. Lowest activity in both sexes was 
recorded during hibernation. Only the males 
showed a significant decrease in acidophilic cells 
during hibernation. There was significant change 
during October, May and in the nonhibernating 
animals, in January (see Table 9). From examina- 
tion of the testes (Reznik-Schiiller and Reznik, 
1973, 1974), ovaries (Ziichner, 1975) and the thy- 
roids (Schlotter, 1976), variation in basophil func- 
tion can be attributed to variation in number and 
function of the gonadotropic component. 
2.20 ORBITAL ADIPOSE TISSUE 
The orbital adipose tissue {corpus adiposum 
orbitae) occupies much of the orbit, especially the 
ventral portion (Figs. 2-18 to 2-21 , 2-32, 2-33). 
At low magnification, it resembles glandular tissue, but higher mag- 
nification demonstrates that it consists of multivacuolated fat cells 
(Fig. 2-73). 
2.21 LACRIMAL APPARATUS 
The lacrimal apparatus (apparatus lacrimalis) 
consists of the lacrimal gland (gl. lacrimalis), the 
accessory lacrimal gland (gl. lacrimalis accessoria) 
(Fig. 2-58) and associated ducts. The lacrimal or 
tear glands have the function of lubricating the 
cornea and preventing the drying of the epithelium. 
In addition to their secretory function, the acces- 
sory lacrimal gland, along with the opthalmic plex- 
us and orbital adipose tissue, has the function of 
protecting the very large eye balls (bulbi oculi). 
2.22 LACRIMAL GLAND 
The lacrimal gland is the smallest of the tear 
glands, lying in a triangle formed by the zygomatic 
arch, the temporal muscles and the eye ball (Fig. 
2-58). Its medial surface presses against the oph- 
thalmic plexus, and it is partially covered on the 
lateral side by the periorbita. 
The glandular structure is of the tubuloalveolar type and the secre- 
tion is serous. 
2.23 ACCESSORY LACRIMAL GLAND 
The accessory lacrimal gland is situated ventro- 
laterally, completely within the orbit (Fig. 2-58). 
It forms a triangular mass between the zygomatic 
arch and the temporal muscle, surrounding the eye- 
ball and the optic nerve, investing them rostro- 
medially as it does in the Chinese hamster (Horber 
et ai, 1974). The gland extends caudally 3-4 mm 
from the zygomatic arch to the area of the optic 
foramen (foramen opticum). Numerous excretory 
ducts (ductuli excretorii) discharge into the con- 
junctival sac (saccus conjunctivae). The fiuid is 
24 
