Welcome to Module 9. This is the second part of the Reproductive System module and we will now discuss the gross anatomy of the female reproductive system. At the end of this module, you should be able to identify the organs and associated structures in the female reproductive system. The female reproductive system includes paired ovaries, paired uterine tubes or the oviducts, the uterus with the uterine horn the body and the cervix the vagina and the vulva the truck of the dog is designed to carry several fetuses during a single pregnancy and is classified to be bicornuate or with two horns the bitch bear litters of young thus they are called multiparus for orientation purposes the system is located in close proximity to the urinary system here is the kidney Here is the ovary, the uterine tube, and the uterine horn.
Let us begin with the female gonads. The ovaries are paired glands, oval, firm in consistency, and often nodular or tuberculate due to the protruding follicles. They are suspended from the body wall by the mesovarium. They are generally found in the sublumbar region, and in dogs it ranges from 1 to 1.5 centimeters. Here is a longitudinal section of an ovary showing its internal structures.
The ovary from a mature animal shows two major division, a cortex and a medulla. The cortex is a parenchymatus zone, it is denser where the follicles are found as you can see here. While the medulla is the vascular zone, it is where the blood supply of the ovaries are found depicted by these blood vessels.
Here is another figure showing the follicles present at the cortex of the ovaries at various stages. From the primary follicle to developing follicles to mature follicles called Graafian follicles. After ovulation, the structures called corpus luteum and corpus albicans will be seen.
This topic will be given emphasis in your histology and physiology courses later. In our level, It is important to at least recognize that in the cortex of the ovaries, we can grossly recognize the mature follicles, the corpus luteum, and the corpus albicans whenever they are present. The corpus luteum is yellow in appearance while the corpus albicans is white somewhat like a scar.
The ovaries must be in its place at all times, thus they are held in place by various ligament. First, we have the broad ligament. This is a large peritoneal sheet suspending the entire genital tract. Specifically, it has the mesovarium, which suspends the ovary itself, the mesosulfinks, suspending the uterine tube, and the mesometrium, suspending the uterus.
The ovarian bursa is formed by the mesosulfinks laterally and ventrally by the proper ligament of the ovary, mesovarium and the ovary itself. The suspensory ligament of the ovary is present only in beach. It is a peritoneal fold which attaches the ovary to the diaphragm in the region of the last rib. And the proper ligament of the ovary attaches the uterine end of the ovary to the ipsilateral uterine horn.
Now let's move to the uterine tubes. The uterine tubes are also known as the ovidux or the fallopian tubes. These are paired convoluted tubes that conduct the ova from each ovary to the respective horn of the uterus and are the usual site of fertilization of ova by the spermatozoa. It is composed of the infundibulum, the fimbria, the abdominal ostium, ampulla, isthmus, and the uterine ostiums. Here is the gross appearance of the uterine tube showing its parts.
The infundibulum is the funnel-shaped portion of the uterine tube adjacent to the ovary that appears to catch the egg during ovulation. At the free ends of the infundibulum are the fimbria. These are the irregular finger-like projections assisting in directing the ova to the uterine tubes.
The abdominal ostium of the uterine tube is the opening at the center of the infundibulum. This is the only opening at the peritoneal cavity to the outside in the female genitalia. The distal opening is called uterine ostium. The ampulla is the thickened part of the uterine tube as you can see here. This is the actual site of fertilization.
And the isthmus is the narrower part and of more convoluted distal part of the tube. The entire uterine tube is being held by the mesosulfinks. Next, we move to the uterus. The uterus is a highly expandable tubular organ where the embryo or the fetus develops.
The uterus of domestic mammals consists of uterine horns, a uterine body, and a cervix or the neck of the uterus. In the case of dog, they have a long uterine horn, short uterine body, and short cervix as depicted in this slide. The horns of the uterus are two musculomembranous extension of the uterine body which are continuously crinially with the uterine tube. They are located at the abdomen. The body of the uterus is a simple muscular tube of varying length between the cervix and the uterine horn.
It lies dorsal to the urinary bladder and ventral to the descending colon and the rectum. The cervix or the neck of the uterus is the most caudal part of the uterus connecting the uterus to the vagina. It has a narrow lumen which is closed most of the time except during estrus, during parturition and a short period thereafter.
It has two openings, the internal uterine orifice which connects the body of the uterus. cranially and the external uterine orifice which connects with the vagina caudally. The cervix is located in the pelvic cavity.
To orient you on the location of the uterus, here is a dorsal view of the abdomen. Here is the paired long uterine horn, the short uterine body, and the short cervix. The uterus is being held by the mesometrium.
Additionally, Here is a picture showing the uterus from a pregnant cat. Take note of the size of the ovary and the size of the developing fetus inside the uterine horn. The vagina, vestibule, and the vulva are the structures at the distal end of the female reproductive tract after the cervix. Here is the extent of the vagina.
It extends from the external uterine orifice of the cervix to the entrance of the urethra. With the vestibule and the vulva, the vagina is considered as the female's copulatory organ and the birth canal. Hymen is poorly developed in dogs and represented by a vestigial mucosa folds at the junction of the vagina and the vestibule.
Next to the vagina is the vestibule. It extends from the urethral opening until the boundary with the vulva. This is the part of the reproductive tract belonging to both urinary and the genital system. It connects the vagina with the external opening called the vulva. The vestibule has organized erectile venous plexuses in the vestibular walls called the vestibular bulbs.
During the coital lock-in dogs, the bulbs erect and press against the penis caudal to the enlarged bulbous glandis. Vestibular gland opens into the vestibule and lubricates the reproductive organs during parturition and copulation. Lastly, the vulva is the terminal end and the only external part of the female genital tract. It has a rounded dorsal commissure and a more pointed ventral commissure.
The vulva has a right and left lips called labia. The vulvar cleft is the opening between the labia leading to the vestibule. The clitoris is homologued to male penis located between the ventral commissure of the vulva. The glands is the only exposed part of the clitoris.
It is located in the clitoral fossa surrounded by the clitoral prepuce. And that ends our discussion on Module 9. As a summary, the female reproductive system is composed of the paired ovaries, the paired uterine ducts, the uterus, vagina, vestibule and the vulva. You should be able to at least recognize those structures including their specific parts.