996 Gh.,t.tiATIVE APPARATUS. 



The Meatus Urinarius and its Valve.— The urethral canal in the 

 female is very short. It passes immediately beneath the anterior sphincter 

 muscle of the vulva, and after a brief course in the texture of the floor of the 

 vagina, it opens into the vulvar cavity by an orifice covered by a large mucous 

 valve : this is the meatus urinarius and its valve. The urinary opening, placed 

 at the bottom of the cavity, at frc- : S^ to 5 inches from the external opening, 

 is wider than the male urethn",, and will admit sounds of somewhat large size, 

 for the catheterism of the bladaer. The valve has its free border inclining 

 backwards, to direct the flow of r.riEe towards the exterior, and prevent its reflux 

 into the vagina. 



(The female urethra is composed of two tunics : a mucoi/s, continuous with 

 that of the bladder and vagina ; and a muscular coat, also a continuation of 

 that belonging to these organs, and chiefly made up of circular fibres ; some 

 flat fasciculi attach it to the periosteum of the ischial bones. The urethra is 

 not suiTounded by a corpus spongiosum, as in the male.) 



The Hymen. — This membrane, when it exists, distinctly separates the 

 vulvar from the vaginal cavity. It is rarely present, however ; though we 

 have observed it several times in the adult Mare.^ It forms a circular partition, 

 fixed by its margin to the vulvo-vaginal walls, as w^ll as to the valve of the 

 meatus urinarius, and is perforated by one or more openings which establish a 

 communication between the vulva and vagina. On many occasions we have 

 found, in old brood-mares, pediculated appendages— the remains of this septum. 

 It is usually represented by a transverse fold of mucous membrane, notched on 

 its free border, which lies above the meatus urinarius. 



Structure of the Vulva. — The vulva offers for study in its structure : 

 1. The mucous membrane lining its interior. 2. An erectile body lying on that 

 membrane, and named the vaginal bulb. 3. Tivo constrictor muscles — anterior 

 and posterior. 4. Two muscular ligaments. 5. The external skin. 



1. Mucous membrane. — Continuous with that of the vagina and bladder, this 

 membrane has a rosy colour, which may become a bright red at the period of 

 oestrum. It often shows, near the free border of the labia — and especially on the 

 mucous cap of the clitoris — black pigment patches, which give it a speckled 

 appearance. It has in its substance a great quantity of mucous follicles and 

 sebaceous glands. The latter exist near the free border, particularly about the 

 clitoris, and especially in the space between that erectile body and the inferior 

 commissure of the vulva, where they meet in several small sinuses. (These 

 glands secrete an unctuous matter possessing a special odour ; they are most 

 active during oestrum.) 



Where the mucous membrane is furnished with papillae, it is covered by a 

 stratified pavement epithelium. 



2. Vaginal (or vestibular) bulb. — This is an organ entirely formed of erectile 

 tissue with wide areolae ; it is divided into two branches {bulbi vestibuli), which 

 arise from the vicinity of the crura of the clitoris and pass on the sides of the 

 vulva, where they terminate in a round lobe. Covered by the posterior con- 

 strictor of the vulva, the vestibular bulb conununicates, inferiorly, with the 

 veins of the corpus cavernosum. The influx of blood into the cells of its tissue 

 contracts the vulvar cavity, and concurs to render the coaptation of the copu- 

 latory organs more perfect during coition. 



• Goubaux gives several instances, in an article on " Purturitiou in the Domestic Animals,* 

 published in the Bectieil de M^d. V^te'rinaire for 1873. 



