Clinical Anatomy of the European Hamster 
5.8.1 Testis 
The testes are compound tubular glands, slightly 
flattened and oval in shape, with the function of 
sperm formation and production of androgen. They 
have a length of 20 to 25 mm and a breadth of 1 1 
to 13 mm in adult animals during spring and sum- 
mer (Tables 4, 6) (Reznik, et ai, 1973). During the 
sexually active period of the year, they each weigh 
about 2.6 g and are completely lodged within the 
vaginal tunic {tunica vaginalis). In autumn and 
winter, the testes weigh only about 0.55 g (Tables 
4, 6, 7, 13, 13a). Only during the mating period are 
the testes located within the scrotum of wild Euro- 
pean hamsters. Coiled testicular veins are detecta- 
ble on the surface of the tunic that tightly invests 
the testis {tunica albuginea) (Fig. 5-61 ). 
The parenchyma of the testicles is yellowish- 
white in color and is of such soft spongy consistency 
that the seminiferous tubules {tubuli seminiferi) 
protrude. During the months of August through 
October, the testes migrate back through the in- 
guinal canal into the pelvic cavity. Within the pelvic 
cavity, both testes rest within a large fat pad which 
almost completely invests them (Fig. 5-62). While 
situated within the pelvic cavity, the right testis 
lies between the caudolateral abdominal wall and 
the urinary bladder. Its caudomedial surface is 
adjacent to the ascending portion of the ampulla of 
the ductus deferens. The left testis is similarly situ- 
ated, except its dorsal surface rests against the 
descending colon. 
During the sexually active period, various cell types are microscop- 
ically demonstrable within the seminiferous tubules of adult males 
Spermatogonias A and B, Sertoli cells, resting spermatocytes, spermat- 
ocytes, spermatids in different stages of maturity (Leblond and Cler- 
mont, 1952a and b) and mature sperm (Fig. 5-63) are visible on the 
tubule walls. 
The interstitial tissue of the testes consists of the cells of Leydig (Fig. 
5-64) and various other cells, some of connective tissue type, together 
with the vessels and nerves. Only during hibernation is spermiogenesis 
reduced to the 15th stage (Fig. 5-65); however, all other cell types are 
represented (Reznik-Schuller and Reznik, 1973, 1974b) (Fig. 5-67). 
5.8.2 Epididymis 
The epididymis serves as storage site for the 
sperm, and is connected with the testis by the rete 
testis. Under the influence of the epididymal secre- 
tion, the maturation of the previously immobile 
sperm is completed. At the time of ejaculation, the 
sperm are transported into the ductus deferens by 
peristaltic contractions. 
The cranial extremity of the head of the epidi- 
dymis {caput epididymidis) (Figs. 5-59, 5-60) -s 
firmly attached to the cranial pole of the testis in a 
hood-like manner and is surrounded by yellowish- 
white fat bodies. The head of the epididymis and a 
portion of the fat bodies lie intra-abdominally. The 
body of the epididymis {corpus epididymidis) is 
quite thin and extends dorsolaterally to the ductus 
deferens and dorsomedially to the testis (Figs. 5-59, 
5-60). The caudal extremity, or tail {cauda epidi- 
dymidis) (Fig. 5-59), has the form of a blunted 
cone and is located at the caudal pole of the testis 
{extremitas caudata). The convolutions of the epi- 
didymal duct {ductus epididymidis) are clearly 
recognizable. At the level of the pelvic inlet, the 
ductus deferens expands to form the prominent 
ampulla, doubles back medially to join the dorsally 
situated urethra through the ejaculatory duct {duc- 
tus ejaculatorius) (Fig. 5-59). The weights and 
sizes of the epididymal regions are given in Tables 
14- 14c. 
The coiled efferent ductules lined with ciliated columnar epithelium 
contain circularly arranged muscle fibers in their walls; thev form the 
small vascular cones (com vascuhsi) of the head of the epididymis (Fig. 
5-66). Their union forms a coiled tube that constitutes the body and 
tail of the epididymis and becomes the ductus deferens (Fig. 5-59). 
Within this duct, the muscle layer becomes thicker, the epithelium is 
pseudostratified columnar and the superficial cells have long, regular 
microvilli. 
5.8.3 Accessory Genital Glands 
The accessory genital glands {gll. genitales ac- 
cessoriae) are grouped around the pelvic part of the 
urethra. Their growth and function are controlled 
by the sex hormones. During hibernation, they are 
markedly atrophied (Tables 15, 16, 16a, 17). The 
secretion of the accessory genital glands provides 
the specific substrate for the completion of the ma- 
turation and mobilization of the sperm. 
5.8.3.1 Vesicular Gland 
The paired vesicular glands {gll. vesiculares) are 
flattened falciform or sickle-shaped coiled tubes 
which are concave medially, lying dorsal to the 
urinary bladder and ampulla of the ductus deferens, 
and ventral to the rectum. The small tubes stretch 
cranially to form two points which often press 
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