Mills Ch35 Prostate

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CHAPTER 35:  Prostate

Subpopulations of these cells also contain a variety of peptide hormones, such as somatostatin, calcitonin, and bombesin. They rest on the basal cell layer between secre- tory cells and often have laterally spreading dendritic pro- cesses. They are not reliably identifiable microscopically except with immunohistochemical and other special stains. Their specific role in prostate biology is unknown, but they presumably have paracrine function. The secretory cells of the prostate contribute a wide variety of products to the seminal plasma. PSA and PAP are produced by the secretory cells of the ducts and acini of all zones, while pepsinogen II (39), tissue plasminogen activator (40), and lactoferrin are normally produced only in the ducts and acini of the central zone. While PSA and PAP have historically been utilized as immunohistochemical markers of prostatic epithelium (or for prostatic origin in car- cinomas), newer antibodies against the NKX3.1 protein are also frequently employed in routine clinical practice (41). The cytoplasmic appearance of the normal secretory cell in all zones is similar and contains an abundance of small clear secretory vacuoles. Vacuoles in peripheral zone and transition zone cytoplasm are tightly packed (42), whereas in the central zone, a more abundant dense cytoplasm is associated with a somewhat wider vacuole spacing and lower vacuole density. Since the secretory vacuoles appear empty by routine microscopy, peripheral zone and transition zone cells are typically pale to clear, while central zone cells are typically somewhat darker (Figs. 35.26 and 35.27).

FIGURE 35.27  Central zone epithelium with eosinophilic cytoplasm and prominent basal cell layer.

The appearance of normal cell cytoplasmon tissue sections is strongly influenced by staining technique and by the type of fixative used. In the peripheral zone and the transition zone, light hematoxylin & eosin (H&E) staining after formalin fixa- tion shows that normal cells are “clear cells” in which a faint network of pale-staining cytoplasmic partitions between vacu- oles can be visualized with careful scrutiny under high magni- fication. Only an occasional cell shows complete outlines that define numerous intact vacuoles, but immunostaining with PSA (Fig. 35.28) or PAP on the same tissue sharply outlines

FIGURE 35.28  Peripheral zone epithelium immunostained with anti- body to PSA. Protein is concentrated in a reticulated pattern that spares vacuole lumens and accentuates portions of vacuole partitions.

FIGURE 35.26  Peripheral zone epithelium showing clear cells in which cytoplasm is barely discernible as composed of a sheet of small empty vacuoles with delicate pale partitions.