REPRODUCTIVE ORGANS IN ANIMALS 33 



The female sex organs, which are visible from the exterior, 

 are known collectively as the vulva, and both the labia and 

 nymphse are included under this term. The labia on the outside 

 are covered with hair. On separating the internal lips or 

 nymphse, not only does the vaginal opening become visible, but 

 also that of the urethra through which the urine is ejaculated. 

 Between the two nymphae lies the vestibule (vestihulum vagince), 

 which encloses the orifice of the vagina and the external orifice 

 of the urethra. On each side of the vestibule venous plexuses 

 — the bulbi vestibuli — are situated. Near the posterior part of 

 the vaginal aperture there are some small mucous glands, known 

 as Bartholini's or Tiedemann's glands, which are especially 

 active during oestrus. The vaginal opening itself in the virgin 

 is closed in the lower half by a membrane called the hymen, 

 which is broken at coitus. At the other or upper (anterior) 

 end of the vulva is the clitoris, which is a solid rod-like organ 

 corresponding to the penis of the male, but not perforated by 

 the urethra. It is a sensitive erectile organ and covered by a 

 prepuce or foreskin like the penis, but it is considerably smaller 

 than that organ. From the clitoris erectile tissue extends 

 around the vaginal opening and beneath the skin of the 

 nymphse. The perineum lies between the vulva and the anus 

 in the same position as in the male. 



The pelvic symphysis in the female may be recognised as a 

 slight prominence at the lower end of the abdomen and above 

 (or anterior to) the vulva. The pelvic hair covers it. There 

 is a cushion of fat padding it, and this is known as the mons 

 veneris. 



The Mammary Glands 



The mammae are compound tubular racemose glands. They 

 are divisible into lobes, which are in turn divisible further into 

 smaller components or lobules. The lobules are formed of the 

 secretory alveoli and the convoluted subdivisions of the chief 

 ducts with which the alveoli communicate, the whole being bound 

 together by connective tissue. The alveoli are lined by secretory 

 cells which discharge the substances composing the milk into 

 more or less centrally placed lumina. During secretion the 



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