Full Title: CAnine Dog Reproductive Information and Process
Author: Mandy Armitage
Date of Publication: April 6, 2015
Research Paper Text:
The developing testes start off in the abdomen. They develop from somatic mesenchymal cells in the genital ridge found caudal to the developing kidneys, around the tenth thoracic vertebra. The testes migrate caudally and retroperitoneal towards the inguinal canal and scrotum. Descent of the testes starts during the last part of pregnancy and first several days after birth. Usually at about 4 to 5 weeks of age they come through the inguinal ring and entered the scrotum. The testes are a paired organ that is oval or walnut shaped that are fixed in a sack. 4 Each testis is suspended by a fold of peritoneum, the mesorchium, and enclosed by it continuation, the vaginal tunic. Inside there is dense fibrous connective tissue internally projecting septula to support the testis. The pouch of skin, smooth muscle, and fascia make up the scrotum. There is a muscle in the scrotum along with the spermatic cord that assist in regulating the temperature of the testicles by raising and lowering them from the body wall. 5
Anatomy of the reproductive tract:
The reproductive tract of a male consists of: The bladder, distensible membranous sac. The Prostate, is an essential part of the male reproductive system, Right and left lobes of the glad enclose the prostatic part of the urethra. 5 Its job is secreting a liquid that works to balance out and protect the seminal fluid and aiding in its motility and survival. The Urethralis Muscle encircles the caudal urethra. The Bulbocavernosus Muscle, a muscle of the perineum, the area between the anus and the genitals. Crura, two tapering process that connect to the ischia process. Penis, contains Bulbous Gland, Glans of the Penis and inside has the balculum (penis bone). The Vas Deferens moves the sperm and the blood is supplies by its own artery. 1
Process of Erection:
Parasympathetic effect 3 — arterial vasodilation and venous constriction; inflow to penis exceeds outflow and blood accumulates in penis; pressure increases within fibroblastic capsules of erectile bodies; pressure mechanically compresses internal veins to further impede outflow; contraction of the penis pumps blood in against the increasing pressure; — the dorsal vein of penis expands pressure within glans; following insertion, the superficially located dorsal veins of penis, which drain the glans, are mechanically constricted. In the dog, the bulbous glands expand following insertion and this explains the “tie” during copulation. 2 A tie can last anywhere from 5 to 60 minutes. The male does not get erect until after insertion, the bone (baculum) makes insertion possible.
Dympathetic pathway — Sperm cells develop in the seminiferous tubeles. During Ejaculation each deferent duct propels spermatozoa and epididymal fluid to the urethra. The mass of sperm cells and epididymal fluid is moved by muscular contraction of the diferent ducts and ischiocavernouse muscles, into the prostatic urethra. It passes straight through ducts and mature under the influence of secretions from the cells lining the duct. It continues up the spermatic cord and terminates by the opening into the prostatic part of the pelvic urethra. This mass is moved toward the external urethal opening, Once the tie is complete the arterial flow returns to normal and muscles relax, permitting the veins to open fully. The two penile retractor muscles contract, assisting the return of the penile glans into the prepuce. 5
Inserted photo is a hairless Chinese Crested at 18 months old.
- Veterinary Gross Anatomy by Thomas F. Fletcher, DVM, PhD & Christina E. Clarkson, DVM, PhD
- Dog Anatomy by Robert A Kainer, DVM, MS & Thomas O McCracken, MS