Download An anatomical study of the feline lower urinary tract

An anatomical study of the feline lower urinary tract
Diploma of Veterinary Clinical Sciences
1975
Tsutomu Kurosawa
Abstract
A review of the literature and anatomical observations on the feline lower urinary tract have
been carried out. The observations were performed on three male and four female cats.
For convenience of description, the lower urinary tract was divided into the bladder, the
preprostatic urethra, the pelvic urethra and the penile urethra.
The long urethral crest which is a continuation of the ureteric fold was observed. Stratified
transitional epithelium was found in the bladder and urethra. It changed to squamous
epithelium at the external urethral orifice in both sexes. However some variation of the
urethral epithelium was recognized in the male animal.
The submucosal layer did not contain a lamina propria muscularis.
The muscle arrangement of the bladder showed a woven mesh-work of smooth muscle,
however no special muscle arrangement could be found as an internal sphincter at the vesicourethral junction.
The male urethral lumen was found to become progressively narrower towards its distal end
and to decrease suddenly at the level of the bulbourethral gland.
In the female the urethral lumen was similar in diameter throughout its length except at the
external urethral orifice.
The submucosa of the urethra contained many sinuses. In the female cat these were fewer
than in the male and longitudinally oriented.
The muscular layer of the urethra consisted of both smooth and striated fibres. The M.
compressor urethrae membranaceae extended into the preprostatic urethra and was composed
of mixed muscle. The M. bulbocavernosus covered and diffused into the bulbourethral gland.
The M. rectocavernosus consisted of both striated and smooth muscles, the former of which
decreased progressively toward the distal end. In the female, the muscle arrangement of the
urethra was similar to the preprostatic urethra in the male.
The adventitial layer surrounding the urethra consisted of loose connective tissue. Dense
fibrous capsules surrounding the prostate and bulbourethral glands were found by previous
authors, but were not found in this study.
The bilobed prostate gland was subdivided into lateral, dorsal and medial parts, the latter of
which consisted of disseminated glandular tissue around the urethra. The epithelium of the
prostate was composed of simple columnar and cuboidal cells.
The bulbourethral gland was about half the size of the prostate. This gland was lined by
simple columnar cells, however its ducts were lined by simple columnar and stratified
transitional cells.
Urethral glands were not found in either sex.
Three varying sized encapsulated nerve endings were found. Large encapsulated nerve
endings which were possibly the Pacinian corpuscles described by previous authors were seen
in the adventitial layer. Medium sized encapsulated nerve endings, 50 to 150 µm in diameter,
were found in the submucosal and muscle layer. Small encapsulated nerve endings of less
than 50 µm in diameter were found in the submucosal layer just beneath the epithelium.
A few glanglia were found in the bladder muscle and most were present in the adventitia.
The os penis which was located dorsal to the urethra was found to be solid bone. The bone
was composed of Haversian systems surrounded by one or two layers of periosteal cells.