THE GENITAL ORGANS OF THE FEMALE. 993 



cylindrical in the os ufpri, and pavemental around the cervix ; here also are 

 found calyciforra cells — a kind of unicellular glands which secrete the thick mucus 

 found in this part. (The cilia vibrate towards the fundus of the organ. The 

 membrane is closely connected with the muscular tunic, and is composed of 

 embryonic, nucleated, connective tissue, without elastic fibres.) The uterine 

 mucous membrane is destitute of papilla except at the cervix (where there are 

 many highly vascular papillae) ; but it lodges numerous simple or ramified 

 glands, which are straight or slightly flexuous at their extremities. At the 

 cervix, these glands enlarge at the bottom, and assume something of the 

 appearance of acinous glands. 



(These mucous glands are designated simple and cylindricaL The first are 

 most numerous towards the cervix ; some, here and there, with their orifices 

 closed, are enlarged, and form small vesicular tumours— the ovula, cysts, ox glands 

 of Nabothi; they secrete the peculiar transparent mucus found here. The 

 cyUndrkal, uterine, or utricular glands are closely clustered together, sometimes 

 bifurcated, often twisted in a spiral fashion, and terminating in a cul-de-sac in 

 the substance of the membrane. In structure they resemble other mucous 

 glands, consisting of a membrana propria, an epithelium of spheroidal cells at 

 the bottom of the tube, and of columnar cells in its duct. During gestation 

 they are much enlarged, and receive the cotyledonal processes of the placenta. 

 At the period of cestrimi, the glandular secretion of tlie uterus is more active 

 than at other times.) 



Vessels — Nerves. — The blood is brought to the uterus by the uterine and utero- 

 ovarian arterks, and is conveyed from it by veins corresponding to the latter. 

 In animals which have been pregnant several times, the vessels are remarkable 

 for their enonnous volume, their tortuousness, and the adhesion of the veins 

 to the neighbouring tissues. (The arteries freely anastomose ; they ramify 

 through the muscular and mucous tunics, constituting coarse and fine networks, 

 which ultimately end in the veins. These are very large, and have no valves ; 

 the plexuses they form are considerable.) 



The lymphatks that proceed from the uterus are as remarkable for their 

 number as their size ; they pass to the sublumbar region. 



The nerves supplying the organ come from the small mesenteric and pelvic 

 plexuses. (In the uterus there are several important nerve-ganglia ; and during 

 gestation it has been ascertained that the nerves, like the vessels, enlarge, and 

 after parturition return to their former size.) 



Development. — Narrow in the foetus, and in the adult which has not been 

 impregnated, the uterus increases in size in animals which have had young 

 several times. 



Functions. — The uterus is the sac in which the embryo is developed. The 

 ovum grafts itself upon the mucous membrane of the organ by its placental 

 apparatus, in order to draw indirectly, from the maternal blood, the materials 

 for its development. This function of the uterus gives rise to most interesting 

 anatomical and physiological considerations, which will be referred to when 

 giving the history of the ovum. 



4. The Vagina (Figs. 535, 536). 



The vagina is a membranous canal with thin walls ; it succeeds the uterus, 

 Bnd terminates posteriorly by an external opening — the vulva. 



Situation and Relations. — Situated in the pelvic cavity, which it passes 



