The use of tannic acid to preserve and promote the staining of protein constituents of the extracellular fluid is described. Its usefulness for delineating the extracellular compartment and detecting changes in capillary permeability is illustrated in experiments on the testis.

Animals↗

PubMed1976

The Sertoli cell occluding junctions and gap junctions in mature and developing mammalian testis.

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Animals↗

PubMed1976

Differentiation of cholesterol compartments in the immature chick testis.

The behaviour of testicular free and esterified cholesterol during early posthatching development and after stimulation with human chorionic gonadotrophin was studied in the immature chick using combined electron microscope and biochemical techniques. The interstitial cells represented about 65% of the testicular tissue and the lipid droplets in the cytoplasm of these cells were considerably depleted after HCG treatment. The lipid droplets isolated from 7-day-old testis contained about 95% of the total esterified cholesterol which was significantly reduced in the testis and isolated lipid droplets after HCG stimulation. The bulk of free cholesterol was associated with the microsomal fraction whose membranes and cholesterol content increased during normal maturation and after gonadotrophin-induced differentiation.

Animals↗

PubMed1975

Subcellular compartmentation of free and esterified cholesterol in the interstitial cells of the mouse testis.

The subcellular distribution of free and esterified cholesterol in mouse testis and the changes occurring in cholesterol content of whole testes and cell fractions after inhibition of gonadotropins with methallibure (ICI 33, 828) and restimulation with human chorionic gonadotropin (HCG) are reported in the present paper. In subcellular fractions, the bulk of free cholesterol is associated with organelles sedimented in the microsomal fraction while esterified cholesterol is mainly stored in isolated lipid droplets. The latter compartment increases in methallibure-treated mice 2.3 fold and is remarkably depleted after administration of HCG. There is a close parallelism between the changes in esterified cholesterol content and the variation in the numbers of lipid droplets found in electron micrographs of interstitial cells of mice receiving similar treatments. By contrast no significant changes were noticed in either free cholesterol concentrations of the microsomal fractions or in the fine structure of organelles associated with this fraction. The dynamic nature of steroidogenesis in the microsomal fraction requires the existence of a free cholesterol pool with a high turnover rate for use as an intermediate in androgen synthesis. On the other hand, the large content of free cholesterol in microsomes and its stability under different conditions suggest the presence of a cholesterol compartment with a slow turnover, as a constituent of the membranes.

Animals↗

PubMed1975

Impermeability of sertoli cell junctions to prolonged exposure to peroxidase.

The competence of the occluding junctional complexes between Sertoli cell has been studied after continuous exposure of the testis to a high concentration of peroxidase for periods of 30 minutes to 4 hours. Horseradish peroxidase in buffered saline solution (10 mg/ml) infused through an indwelling polyethelene tube implanted interstitially in the testis becomes widely distributed throughout the organ via the extensive system of lymphatic sinusoids. All the components of the testicular interstitium become heavily infiltrated. A large amount of peroxidase accumulates in the acellular layers of the lamina propria of the seminiferous tubules. Some traverses patent intercellular clefts between myoid cells and enters the interspaces of the basal compartment of the epithelium. The Sertoli cell junctions effectively prevent any further penetration of peroxidase toward the adluminal compartment and in no case was the tracer observed in the tubular lumen. The present study extends previous observations based on brief exposure to tracers and confirms the conclusion that the occluding Sertoli cell junctions are highly impermeable to small tracers and constitute the main structural component of the blood-testis barrier.

Animals↗

PubMed1975