Morphometric analysis of the fate of secretory epithelial cells in the ventral lobe of the rat prostate during massive apoptosis

Orchiectomy causes marked, rapid involution of the prostatic secretory epithelium. Concurrently, macrophages, which in normal glands are small and rarely occur at the base of the secretory epithelium, increase in size and number. Apoptotic cells are engulfed by companion epithelial cells and also by macrophages. In secretory cells and macrophages, dense bodies progressively increase in number and store membranes derived from dead cells of the secretory epithelium. In this work, we examined the contributions of the various routes of disposal of demised secretory epithelial cells of the rat prostate, induced to enter in apoptosis by retrieval of androgen. Specifi cally, we sought to determine how much membrane surface area derived from apoptotic cells of the secretory epithelium could be stored in dense bodies, and how these data compared with the disposal of dead cells via the glandular lumen. Glands from unoperated controls (day 0) and from rats examined 12 h and 1, 2, 3, 4, 5, 6, 7, 8, and 9 days after orchiectomy were studied morphometrically. The total membrane surface area of rough and smooth endoplasmic reticulum, Golgi apparatus, mitochondria and vesicles declined from 6.75 x 103 \ub5m2 in non-castrated rats to 1.12 x 103 \ub5m2 nine days after castration. Similarly, the total surface area of the secretory epithelium decreased from 10.6 x 1011 \ub5m2 in non-castrated rats to 0.204 x 1011 \ub5m2 nine days after castration. Geometrical models revealed that 1 \ub5m3 of dense body accommodated at least 142 \ub5m2 of myelin-like membrane surface area. Three to four days after castration, the total volume of intramacrophage dense bodies peaked (~5 x 106 \ub5m3) and represented 1-2% of the volume of intraepithelial dense bodies (~4 x 108 \ub5m3). The minimum membrane surface area that could be stored in dense bodies of the secretory epithelium on post-castration days 0, 1, 2, 3, 4 and 9 was 1.4%, 9%, 16%, 23%, 28% and 44%, respectively, of the total membrane surface area of the secretory epithelium. The total number of cells counted in the glandular lumina on days 4 and 5 represented 2.6% and 1.2% of the number of cells lost in the glands between post-castration days 3 and 4 and days 4 and 5, respectively. As stated, a relevant source of cell disposal is represented by the autophagic process which occurs in the secretory epithelial cells and results in the formation of dense bodies. Digestion of remnants of apoptotic secretory epithelial cells in the cytoplasm of macrophages and removal of dead cells via the intraluminal route accounted for some 1-3 to 3-4 % , respectively, of the total cell death