Heterogeneity of intrafollicular somatic cells and ovulated cumulus masses as evidenced by delta 5-3 beta-HSDH activity.

The histochemical localization of delta 5-3 beta-HSDH in individual follicles isolated from the adult mouse ovary and in ovulated cumulus cell-oocyte masses recovered from the oviduct was examined using a new embedding technique. The procedure employed involves the histochemical staining of such tissue for delta 5-3 beta-HSDH with subsequent embedding in GMA (glycol methacrylate). This method not only permits the acquisition of sections as thin as 3 micron but also preserves the histological detail of the tissue allowing for the specific cellular localization of the enzyme. Results obtained from this technique far surpass those obtained from frozen material. Virgin female mice were injected with PMSG and sacrificed either 10 or 17 h later in order to acquire preovulatory or ovulated oocyte-cumulus cell masses, respectively. The sites of localization of delta 5-3 beta-HSDH corresponded to sites demonstrated by histochemical studies on frozen tissue sections; however, the present study revealed that not all cells of a specific type within the same follicle reacted with the same intensity. Granulosa cells lining the walls of vesicular follicles displayed different degrees of enzyme activity based on their distance from the basement membrane. Intrafollicular tranformed cumulus masses and cumulus cells of ovulated masses within the oviduct did not react uniformly in that some were positive for the enzyme and others were not. Such results indicate that not all cells of a given type in the ovary possess similar delta 5-3 beta-HSDH activity at a particular time. Thus, the cells comprising a specific cellular component of the ovary should be treated as individual entities and not as a homogeneous group with respect to their metabolic activities.