This micrograph, a higher magnification of Figure 23.27, shows the stratified squamous epithelium and mature cells with small pyknotic nuclei. Note a single layer of basal cells and two or three layers of cells undergoing differentiation (with eosinophilic cytoplasm). Projections of the connective tissue papillae into the epithelium give the connective tissue–epithelial junction an uneven appearance. The tips of these projections often appear as isolated structures surrounded by epithelium (arrows). 180.
are more plentiful in the lower third of the vagina are probably associated primarily with pain and stretch sensations.
The female external genitalia consist of the following parts, which are collectively referred to as the vulva and have a stratified squamous epithelium as follows.
 The mons pubis is the rounded prominence over the pubic symphysis formed by subcutaneous adipose tissue.
 The labia majora are two large longitudinal folds of skin, homologous to the skin of the scrotum, that extend from the mons pubis and form the lateral boundaries of the urogenital cleft. They contain a thin layer of smooth muscle that resembles the dartos muscle of the scrotum and a large amount of subcutaneous adipose tissue. The outer surface, like that of the mons pubis, is covered with pubic hair. The inner surface is smooth and devoid of hair. Sebaceous and sweat glands are present on both surfaces (Fig. 23.29).
 The labia minora are paired, hairless folds of skin that border the vestibule and are homologous to the skin of the
The examination of Pap smears is a valuable diagnostic tool in evaluating the vaginal and cervical mucosae (Fig. F23.5.1). The superficial epithelial cells are scraped from the mucosa, spread on a glass slide, fixed, and then stained with the Papanicolaou stain (a combination of hematoxylin, orange G, and eosin azure). Examination of the Pap smear provides valuable diagnostic information about the epithelium regard-ing pathologic changes, response to hormonal changes dur-ing the menstrual cycle, and the microbial environment of the vagina. The synthesis and release of glycogen by the epithelial cells of the uterus and vagina are directly related to changes in the pH of vaginal fluid. The pH of the fluid, which is normally low, around pH 4, becomes more acid near midcycle as Lactobacillus acidophilus, a lactic acid–forming bacterium in the vagina, metabolizes the se-creted glycogen. An alkaline environment can favor the growth of infectious agents such as Staphylococci, Corynebacterium vaginale, Trichomonas vaginalis, and Candida albicans, causing an abnormal increase in vaginal transexudates and inflammation of the vaginal mucosa and vulvar skin known as vulvovaginitis. These pathologic con-ditions are readily diagnosed with Pap smears. Specific antimicrobial agents (antibiotics, sulfonamides) are used to-gether with nonspecific therapy (acidified 0.1% hexetidine gel) to restore the normal low pH in the vagina and thus pre-vent the growth of these agents. In addition, cervicovaginal Pap smears are widely used for diagnosis of early cervical cancer as well as endome-trial carcinoma. Because cervical lesions may exist in a noninvasive stage for as long as 20 years, the abnormal cells shed from the epithelium are easily detected with a Pap smear examination. Microscopic examination of these cells permits differentiation between normal and abnormal cells, determines their site of origin, and allows classifying cellular changes related to the spread of the disease. The Pap smear is an extremely effective and in-expensive screening method in preventing cervical can-cer. Most of the cell abnormalities detected by Pap smears are in the precancerous stage, which allows the clinician to implement appropriate therapy.