[Light and electronmicroscopic examinations on granulosa and theca of preovulatory and freshly ruptured follicles of human ovaries (author's transl)]

Abstract

In a first paper, the structural and functional relationship of granulosa and theca of follicles during early development stages was reported. On the special question of whether and from which moment these two tissue formations are involved in the steroidbiosynthesis, our electronmicroscopic examinations have given a further insight to this. Neither the granulosa nor the theca folliculi of primordial, primary and secondary follicles show definite morphologic submicroscopic criteria of the steriodbiosynthesis. In the resting tertiary follicle, the electronmicroscopy defines the theca cells as steroidbiosynthetic active cells, whereas the granulosa cells of this stages of follicle demonstrate the morphologic characteristics of protein-synthetic active cells. Our, under physiological conditions, systematically conducted light and electronmicroscopic studies of preovulatory and freshly ruptured follicles showed remarkable structural changes in the granulosa, as well as in the theca folliculi. For the follicle granulosa cells of the preovulatory follicle, the studies could demonstrate a structural transformation process of proteinsynthetic active to steroidbiosynthetic active cells. This transformation process can be seen in the nucleus. Especially recognizable is the continuous change from rough to smooth endoplasmatic reticulum in the cytoplasm of most of the follicle granulosa cells, which apart from that, often displayed whorle-like formations. Furthermore, we noticed striking changes of the paraplasmatic structures, especially of the fat, present in various stages in the cytoplasm of the follicle granulosa cells. We also noticed large mitochondria, which showed a lot of vesicular cristae. Numerous existing Golgi-fields contained many little homogenous fat-like droplets, which were surrounded by a thin osmiophilic membrane. This recognizable transformation process of the proteinsynthetic active granulosa cells to the steroid cells is quite completed in freshly ruptured follicles, according to our examinations. Although the theca cells have already been defined submicroscopically in the resting tertiary follicle as steroidbiosynthetic active cells, we see in this cellgroup in the preovulatory, as well as in the freshly ruptured follicle a remarkable conspicuous size-increase of the mitochondria. Apart from that, there are wide areas which are solely occupied by smooth endoplasmatic reticulum, whereas other structures, for example fat, are scarely seen. As our examinations have shown, there is a close relationship between the transformation process in the granulosa and the theca of preovulatory follicles and the theca of preovulatory follicles that, the increasing concentration of progesteron in serum, which begins prior to the ovulation can be regarded as a product of the follicle granulosa cells being transformed to steroid cells.