Light Microscopic Immunocytochemical Localization of 3β-Hydroxy-5-ene-steroid dehydrogenase/Δ5-Δ4- Isomerase in the Gonads and Adrenal Glands of the Guinea Pig

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Abstract
The enzyme complex 3.beta.-hydroxy-5-ene-steroid dehydrogenase/.DELTA.5-.DELTA.4-isomerase (3.beta.HSD) is involved in the biosynthesis of all classes of active steroids, namely glucocorticoids, mineralocorticoids, progesterone, and sex hormone steroids. To obtain precise information about the cellular and subcellular localization of 3.beta.HSD in the gonads and adrenals of the guinea pig, we have proceeded to immunocytochemical localization of the enzyme using antibodies developed against purified human placental 3.beta.HSD. In the testis, specific immunostaining was restricted to the cytoplasm of the interstitial cells. In the ovary, on the other hand, immunostaining was found in the cytoplasm of the cells of the corpus luteum and theca interna. The granulosa cells of the follicles were not immunolabeled, with the exception of one layer of cells in contact with the zona pellucida. This restricted labeling was observed in growing and mature follicles, but not in primordial and small primary follicles. In the adrenals, the three zones of the cortex were labeled, whereas no staining could be detected in the medulla. Contrary to findings in testis and ovary, staining was found in both the cytoplasm and nuclei of adrenocortical cells. The present data suggest a functional interaction between the ovocyte and the specialized layer of 3.beta.HSD-containing granulosa cells which might play a role in ovocyte maturation.