Morphological and hormonal changes following vasectomy in rats, suggesting a functional role for Leydig-cell associated macrophages.

The effects of bilateral vasectomy on hormone serum levels as well as Leydig cell and associated macrophage structure were analysed in parallel in rats 36 weeks following the operation. Serum testosterone was decreased in vasectomized rats (1.96 +/- 0.11 ng/ml) compared with control animals (3.44 +/- 0.22 ng/ml, p less than 0.05). Vasectomy also resulted in an increase in serum luteinizing hormone (LH) to 0.299 +/- 0.02 ng/ml compared to the control group (0.175 +/- 0.01 ng/ml, p less than 0.05). Also serum follicle-stimulating hormone (FSH) was increased following vasectomy (350.88 +/- 15.5 ng/ml) compared to 132.0 +/- 4.8 ng/ml in control animals (p less than 0.01). Morphometric analysis of Leydig cells showed hypertrophy with a 19% increase of total cell area, p less than 0.01 (cytoplasm 28%, nucleus 8% increase). On the ultrastructural level, leydig cells demonstrated massively dilated smooth endoplasmic reticulum characteristic for stimulated cells. There was also a significant hypertrophy of the Leydig cell-associated macrophages. The macrophage cell area was enlarged by 22%, p less than 0.01 (cytoplasm 25%, nucleus 18%). Vasectomy also led to remarkable ultrastructural changes of macrophages with a marked dilated and extended rough endoplasmic reticulum. Macrophages were found in apposition to Leydig cells with close cellular contact zones, and they frequently formed cell extensions on Leydig cells. Our data obtained following vasectomy indicate that, by their close contacts to Leydig cells, as well as the known influence on Leydig-cell steroidogenesis, macrophages may form the basis of a local immunoendocrine regulation of the pituitary-gonadal axis.

[Interrelationships between pars intermedia and posterior pituitary with regard to corticotrophic and thyrotrophic partial function in rats]. / Zum Verhalten von Pars Intermedia und Neurohypophyse im Rahmen der Wechselwirkung zwischen corticotroper und thyreotroper Partialfunktion bei Ratten.

Functional interrelationships between the pars intermedia and posterior pituitary were proved under different experimental conditions. After stimulation of the thyrotropical axis of rats by an acute intraperitoneal application of 50 microgram TRH/rat the nuclear sizes of the thyroid follicular and the anterior pituitary thyrotropical cells increased according to a monophasic time curve with maximal amplitude at the time of 30 minutes. Interestingly, the nuclear sizes of the posterior pituitary cells were also enhanced. Under the same experimental conditions the nuclear areas of the cells of the external layer of the adrenal zona fasciculata decreased as did the nuclei of the pars intermedia cells (without regard to the cell type or localization of the cells in the intermediate lobe). Stimulation of the adrenocorticotropical axis by an acute injection of 0.2 ml isotonic saline solution/rat was followed by a time-dependent increase of nuclear sizes of the fasciculata cells and pars intermedia, whereas the nuclear volumes of the thyroid follicular cells, the anterior pituitary thyrotropical cells and the posterior pituitary cells decreased. Thus the functional state of the pars intermedia was in accordance with that of the adrenal cortex. Also the posterior pituitary cells responded to stimuli applied to the thyrotropical axis at the same degree as the thyrotropic organs themselves. Between the nuclear sizes of the pars intermedia and posterior pituitary we established the same inverse functional relationships as between the adrenal cortex and the thyroid gland.