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Connexin 43 (Cx43) is the most abundant and ubiquitously distributed gap junction protein in testicular cells. Lack of Cx43 expression results in male infertility. We investigated whether Cx43 is expressed and regulated in Leydig, Sertoli and germinal cells at different stages of postnatal development. Cx43 was detected using three different antibodies shown by immunoblotting to be highly specific. At different postnatal ages Cx43 localization was compared in serial or double labeled testicular cryosections with immunocytochemical distribution of steroidogenic enzyme, 3 ␤hidroxysteroid-dehydrogenase (3␤HSD), Mullerian inhibitory hormone (MIH), and germinal nuclear cell antigen (GNCA1), which are specific markers of interstitial Leydig, Sertoli and germinal cells, respectively. In the interstitium, round cell clumps (RCC) with lipid droplets positive for 3␤HSD and Cx43 were frequently found at intertubular areas at birth and Cx43 was mainly localized at cell membrane appositions. From day 3, the number and size of 3␤HSD-positive RCC started to decrease, and reached a minimum at 7-14 dpp; Cx43 expressed by them is progressively downregulated. From day 21 an increase in the size and number of RCC positive for Cx43 and 3␤HSD was found that continued at 24, 26 and 28 days and reached a maximum at 35 and 60 dpp. Biphasic expression of interstitial Cx43 and 3␤HSD was also found to be positively and temporally correlated with fluctuations in intratesticular testosterone content at all ages studied. In the seminiferous cord (SC), Cx43 was expressed at birth between adjacent Sertoli cells (MIH positive) localized at the periphery, as well as in their cytoplasm projections that surround centrally localized gonocytes. From days 3 to 7, Cx43 labeling increased in Sertoli cells mainly at their apical border. At day 14, Cx43 distribution in Sertoli cells changed from apical to basal in parallel to migration of germinal (GNCA1-positive) cells from the periphery to the center of the SC. At all these ages, Cx43 was also localized at cell borders between Sertoli and germinal cells. In conclusion, this study demonstrates that Cx43 in Leydig cells is regulated during postnatal development in an age and functional dependent manner. In the tubule, it is demonstrated that Cx43 is modulated in Sertoli cells during the neonatal and prepubertal period. We also provide evidence for the first time that Cx43-gap junctions communicate between Sertoli and germinal cells before and during the first wave of spermatogenesis. Anat Rec 264: [13][14][15][16][17][18][19][20][21][22][23][24] 2001.

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In the present studies we analysed the main physicochemical and biological properties of the several isoforms of human pituitary follicle-stimulating hormone (hFSH). Extracts of total anterior pituitary glycoproteins from adult donors were submitted to chromatofocusing and several forms of immunoactive hFSH with isoelectric points (pI) ranging from 7.6 to 3.8 were identified. An additional isoform was detected after passing through the chromatofocusing column a 1.0 M NaCl solution (salt peak). Each hFSH isoform or pool of neighbouring isoforms (pI value 7.6-7.1, pool I, 1.5 +/- 0.13% of total immunoactivity recovered; pI value 5.9-5.3, pool II, 8.9 +/- 1.6% of total; pI value 5.0-4.7, pool III, 14.4 +/- 1.4% of total; pI value 4.5-4.1, pool IV, 54.8 +/- 4.9% of total; pI value 3.9-3.8, pool V, 3.67 +/- 0.9% of total; salt peak, pool VI, 16.8 +/- 4.8% of total) eluted as single hFSH peaks after Sephadex G-100 exclusion chromatography (apparent Mr 60,000). Even though hFSH present within each pool was recognized by a receptor preparation, the receptor-binding activity expressed as the radioreceptor assay:radioimmunoassay (RRA/RIA) activity ratio varied with the pI value of the particular hFSH isoform tested; starting from a pI value of 5.9, the receptor-binding activity of hFSH decreased from 4.25 +/- 0.28 to 1.17 +/- 0.14, as the pI value of the corresponding isoform declined. A similar trend was observed when the potency of each isoform was assessed by an in vitro bioassay.(ABSTRACT TRUNCATED AT 250 WORDS)

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