Small and Large Animals Male Reproductive Organs PDF

Small and Large animals Male Reproductive Organs Cristian Dezdrobitu, DVM, MSc, PhD 1 Male Genital Organs Dog 2 Scrotum Protects and supports the testes Dual chambered pouch...

Small and Large animals Male Reproductive Organs Cristian Dezdrobitu, DVM, MSc, PhD 1 Male Genital Organs Dog 2 Scrotum Protects and supports the testes Dual chambered pouch Separated by a septum (2) into right and left halves Each half containing a testis (7), epididymis (9), and the distal portion of the spermatic cord (including 8 and other elements) 3  Layers of the scrotum Outer skin layer is superfine closely associated with a smooth muscle layer (tunica dartos 1 cache m. - puckering or wrinkling of scrotum) I Spermatic fascia External and internal (not distinguished) Vaginal tunic Parietal and visceral Vaginal cavity is in between these 2 Ñm layers 4  eys Cremaster muscle the vagaltunic Outside of Caudal slip of the internal abdominal oblique m. Attaches to the vaginal tunic near the testis Pulls the testis closer to the body (elevate testes) Interm tofend v58 5  Blood supply: Scrotum External pudendal a. 6  Testes Male gonad Located in the scrotum Surface is invested by the tunica albuginea Covered by the visceral vaginal tunic 7 Testes Orientation depends on species Suband veg Iguiding 8  Blood supply Blood supply Testicular a. Testicular v. forms the pampiniform plexus that convolutes around the artery, lymphatics and nerves 9  Descent of the Testes Testes migrate from their developmental position near the kidneys to a location outside the body (scrotum) There are two phases of the migration of the testes through the inguinal canal For the first phase the extra-abdominal part of the gubernaculum increases in length and volume dilating the inguinal canal allowing the testes to pass through it For the second phase the gubernaculum will regress into a small fibrous structure making room for the testes 10  C. A. B. D. 11 Cryptorchidism “Hidden testicle” When one or both of the testes are retained within the abdominal cavity or trapped in the inguinal canal 12  Open vs. closed castration Closed Incise through the skin, tunica dartos m., and separate the spermatic fascia from the parietal vaginal tunic You are leaving the parietal vaginal tunic intact, therefore not exposing the vaginal cavity (and in turn the peritoneal cavity) to the external environment 13  Open castration Incises the skin, tunica dartos m., spermatic fascia, and parietal vaginal tunic This opens the vaginal cavity which is continuous with the peritoneal cavity and “exposing” it to the external environment 14 15 Spermatic cord Superficial inguinal ring Testicular artery, vein and nerves Comprised of the ductus deferens, testicular v., a. and n., and their serous membranes (mesoductus deferens and mesorchium) Ductus deferens Dog 16 Epididymis Maturation and storage of spermatozoa 3 parts Head- sperm enter here from the testes Body Tail- continuous with the ductus deferens 17 18 Ligaments of the Scrotum, Testis, and Epididymis Proper ligament of the testis Connects testis to the tail of the epididymis Ligament of the tail of the epididymis Connects tail of the epididymis to the layers of the vaginal tunic Scrotal ligament Connects tail of the epididymis to the tunica dartos m. 19  Ductus deferens DOG Continues from the tail of the epididymis Crosses lateral ligament of the urinary bladder to enter into the pelvic urethra Genital fold- peritoneal fold between each ductus deferens 20 Ductus deferens Transports sperm from the tail of the epididymis to the urethra Opens at the colliculus seminalis 21  Blood supply Blood supply Artery of the ductus deferens DOG 22  Penis 2 types of penis Musculocavernosus Fibroelastic Erection is brought about by a relaxation of the retractor penis muscle and the erectile tissue filling with blood 23  Musculocavernosus type of penis Found in the stallion, dog and the tom cat (and human) Large amounts of erectile tissue Cat Dog 24  Fibroelastic type of penis Limited erectile tissue (still present) Contain a sigmoid flexure Bull, boar, ram 25 26  Erectile tissue Corpus cavernosum Dog Contributes to crus Extends distally to form the dorsal columns of the body of the penis Corpus spongiosum Expands as the bulb of the penis proximally Surrounds the entire penile urethra Continuous as the glans (apex) of the penis distally 27  Penis Composed of 3 parts Root Consists of right and left crura, bulb, and surrounding musculature Body Intermediate to the root and glans Glans Distal most aspect of penis Consists of bulbus glandis and pars longa glandis in Dog the dog Contains the os penis in the dog and tom cat 28 Root Crus of the penis (bilateral) Dog Proximal end of the corpus cavernosum (erectile tissue) and affiliated tunica albuginea Anchors the penis to the ischiatic tuberosity Covered by the ischiocavernosus m. Bulb of the penis Urethra surrounded by Lies between the crura corpus spongiosum penis Retractor penis m. (ischial arch) Courses along the caudal Corpus spongiosum aspect of the penis Externally covered by the 29 bulbospongiosus m.  Ischiocavernosus m. Paired Area of the root of the penis 30  Bulbospongiosus m. Overlaps the bulb of the penis Extends down the caudal and ventral surfaces 31  Penis Body of the penis Begins where the two crura join to form the dorsal erectile columns of the penis From the root to the glans Dog 32 Glans of the penis (unique to species) Bulbus glandis (dog) Expansion of the corpus spongiosum in the proximal third of the penis Contributes to the “tie” during copulation Dog Pars longa glandis (dog) Erectile tissue structure Apex of the penis Deforms during intromission and allows the urethral opening to shift dorsally 33 PLG = Pars Longa Glandis BG = Bulbus Glandis 34 Os penis (dog, tom cat) Visceral bone within the glans penis Urethral groove located along the ventral aspect (not present in tom cat) Provides protection of urethra 35  Os penis (dog) https://www.vetstream.com/treat/exotis/ferrets/illustration/j-shaped-os-penis This radiograph documents multiple well-defined, mineral opaque calculi within the penile urethra (arrows). 36 https://www.cliniciansbrief.com/content/urinary-calculi-image-gallery-8-11 https://commondescentpodcast.wordpress.com/2019/01/26/episode-53-the-baculum-penis-bone/ 37 Equine penis – glans Corona glandis Cranial surface – greatest circumference of the glans Column glandis Narrowing of the glans caudal to the corona Urethral process with external urethral orifice Fossa glandis X Depression surrounding urethral process Urethral sinus Diverticulum off the fossa glandis dorsally Located above the urethral process Constantinescu Fig. H4.14 Courtesy of Dr. Terri Clark Smegma accumulates here Tom cat Cornified spines Testosterone responsive Anus tissue on glans penis Present for approximately 30 Scrotum days post orchiectomy Penis Helpful when determining if retained testis is present Prepuce  Blood supply: Penis The internal pudendal artery is the primary source of blood to the penis After giving rise to the wit ventral perineal artery, the internal pudendal artery continues as the artery of the penis Artery of the penis gives rise to the artery of the bulb, Bose deep artery of the penis, and then continues as the dorsal artery of the penis The external pudendal artery also supplies branches that anastomose with the preputial branch of the dorsal artery of the penis Dog 40 Blood supply: Penis 29. Internal pudendal a. 39. Ventral perineal a. Bull/Boar/Ram 41. Dorsal scrotal a. 42. Artery of the penis Internal iliac a. 43. Artery of the bulb of the penis internal pudendal a. 44. Deep artery of the penis artery of the penis 45. Dorsal artery of the penis Artery of BrE the bulb of the penis Deep artery of the penis Dorsal artery of the penis Bull 41 Blood supply: Penis Stallion 1. Internal iliac a. (19) internal pudendal a. (29) artery of the penis (42) Bakit down Stallion 42 Stallion 2. External iliac a. (7) (deep femoral a.) pudendoepigastric de trunk (9) external pudendal a. (12) cranial artery of the penis (18) Bukit Stallion 43 Stallion 3. Internal iliac a. (19) Bent caudal gluteal a. (24) cranial gluteal a. (26) obturator a. (27) middle artery of the penis (28) Go Stallion 44  Male urethra Divided into 2 parts Pelvic urethra Colliculus seminalis Penile urethra (penile) Continuation of the pelvic portion, begins at the ischial * arch Surrounded by corpus spongiosum Dog 45 Dyce 4th ed. Fig. 15-27  Urethralis m. Striated m. that surrounds the pelvic urethra Bull Bull and boar 46  Prepuce Fold of skin covering the glans penis External lamina The haired skin of the outer surface Internal lamina Terminates at the fornix, where it becomes continuous with the skin of the glans (penile lamina) 47  Prepuce In the equine the internal lamina gives rise to an additional, circular preputial fold and External layer of Internal layer of preputial fold which, with its cranial border, forms the preputial fold preputial ring Free part of penis Glans penis In the erect penis, the internal and external layers of the preputial fold (part of the Preputial ring internal layer of the prepuce) adhere to the penis forming the penile layer of the prepuce In the erect penis, the preputial ring is 48 applied to the penis 49 CEM in the Stallion Swab: 1. Distal urethra 1 2 (urethral process) 2. Fossa glandis 3. Urethral sinus 4. Shaft of penis and prepuce 3 4 50  Preputial diverticulum Found in the boar “Boar taint” Foul smelling fluid that contains a pheromone If the contents of the diverticulum collect excessively, the appearance may mimic umbilical hernia 51  Blood supply: Prepuce Internal pudendal a. (Ventral perineal a.) External pudendal a. 52  Accessory sex glands Responsible for the production of seminal plasma Size of accessory glands decreases with castration 1. Ampulla 2. Vesicular glands (seminal vesicles) 3. Prostate gland 4. Bulbourethral gland (Cowper’s gland) Canine 53  Ampulla Enlargements of the ductus deferens Open into the pelvic urethra Present in the stallion, bull, ram Dog - not a real ampulla but they have ampullary glandular tissue in the final segment of the deferent duct 54  Vesicular glands Paired glands Dorsocranial to the pelvic urethra Open into the pelvic urethra Present in the stallion, bull, ram, boar 55  Prostate Lies in close proximity to the junction between the bladder and the pelvic urethra Great species variation with regard to shape and location Corpus and disseminate prostate 56 Courtesy of Dr. Terri Clark  Bulbourethral glands Paired on either side of the urethra near the ischial arch Very large in the boar In the ram, bull, and stallion, the gland is quite small and buried under the bulbospongiosus m. Present in the stallion, bull, ram, boar, and tom 57 Species Ampulla Vesicular Prostate Bulbourethral Stallion + + + + Bull + + + + Boar - + + + Ram + + + + Buck + + + + Dog + - + - Tom Cat - - + + 58  Mechanism of Erection - FYI Erection is achieved by the filling of the spaces of the erectile tissues with blood. Erection is a Parasympathetic event “Point” Pelvic nerve Ejaculation is a Sympathetic event “Shoot” Hypogastric nerve Maintenance of erection is via activation of pudendal nerve 59  Mechanism of Erection - FYI Increased blood flow to penis results in filling of cavernous spaces Constriction of the veins of the penis partially prevents venous return, assisting in maintenance of blood pressure within cavernous tissues Tunica albuginea also acts to maintain pressure within erectile tissues 60  FYI Upon Intromission: Contraction of penile musculature forces blood into the glans penis Engorgement of the female vestibular bulbs further restricts venous outflow from the penis, allowing the bulbus glandis to maximally engorge (results in the tie) Tie is maintained until penile musculature relaxes and arterial blood pressure drops to normal 61 62