The aim of this study was to explore the competence of the blood-testis barrier (BTB) using electron opaque tracers in diverse human testicular pathologies associated with Sertoli cell only syndrome. Two groups of patients were studied: (1) those with complete depletion (absence) of germ cells, and (2) those with severe germ cell depletion but with some germ cells left in the seminiferous epithelium. The first situation was associated with cryptorchidism with absence of germinal cells, idiopathic cases of aplasia of germ cells, peritumoral areas surrounding small seminomas where the seminiferous tubules were observed to contain a predominant population of Sertoli cells, or long estrogen treatment. The second was found also in cryptorchidism with early germ cells, idiopathic azoospermia, and oligospermia associated with sterility. In the first situation, seminiferous tubules lacked lumen and Sertoli cells had immature morphological characteristics, i.e., oval nuclei with smooth profiles, even heterochromatin distribution and a single, small nucleolus. Inter-Sertoli tight junctions were tortuous, interrupted, and mostly perpendicular to the basal lamina. Lanthanum hydroxide or nickel nitrate permeated most of the inter-Sertoli spaces, indicating disruption of the BTB. In the second situation, seminiferous tubules had a lumen, and Sertoli cells exhibited a mature appearance with large tripartite nucleoli and irregular, highly infolded nucle-olemma. Only spermatogonia or primary spermatocytes showing diverse degrees of cell involution were found. Numerous inter-Sertoli tight junctions, uninterrupted and parallel to the basal lamina, stopped the electron opaque intercellular tracers close to it; this meant the assembly of a competent BTB. Therefore, a close correlation was found between morphological parameters of Sertoli cell maturity, including their tight junction organization, and BTB integrity.

No abstract

The short-term effect of a subcutaneous injection of 3 mumol of cadmium chloride/100 g body weight were examined 90 min later in male rats. The main target of cadmium, as shown by electron microscopy, was the endothelial lining of capillaries of the caput epididymidis. Intercellular junctions between endothelial cells were disorganized, ranging from slight separation between cytoplasmic leaflets to wide gaps which communicated freely with the pericapillary tissue. Disruption of platelets and intravascular clotting followed these early endothelial lesions, and clotting was found in venules as an extension of clotting from the capillaries. Pre-treatment with zinc (300 mumol zinc chloride/100 g body weight) prevented all of the lesions described above.

Langerhans cells (LCs) are dendritic components of stratified epithelia, presenting antigens to other cells of the immune system that play a crucial role in local defense. The paucity of information about their significance in the esophageal mucosa was addressed by studying their distribution and morphology in this particular location. LCs were identified by immunohistochemical detection of CD1a, a cell-specific marker, using a monoclonal antibody, as well as by electron microscopic identification of characteristic Birbeck granules, among other typical morphological features. Cell counts carried out at 25 and 35 cm distal to the dental arch demonstrated significant differences in number and size between the two locations. The upper region contained 10.4 Ϯ 0.8 cells (mean Ϯ SEM) vs. 18.4 Ϯ 1.4 cells in the lower region. Also, cells in the lower region were larger and appeared to have longer dendritic processes. To our knowledge this is the first report of regional differences in number and morphology of LCs in human esophageal mucosa. Anat Rec 268: 360 -364, 2002.

Pregnant rats (day 13) received 10 mg/kg of Busulfan i.p. The seminiferous tubules of their offspring from post-natal age 1 day up to day 35 were examined with TEM after fixation plus intercellular tracers, and with freeze-fracture techniques. During this period, the inter-Sertoli tight junctions of controls increase both in number and in length. Between days 10 and 13 the seminiferous cords have numerous preleptotene and leptotene spermatocytes surrounded by tracer. The inter-Sertoli junctions are tortuous and predominantly perpendicular to the basal lamina. Between ages 13 and 20 days the seminiferous epithelium reaches zygotene-pachytene stages. The tracer is stopped at the inter-Sertoli junctions at this stage, whereas it still permeates tubules displaying preleptotene and leptotene spermatocytes. Freeze-fracture shows that the orientation of inter-Sertoli junctions has changed to parallel, both to each other and to the basal lamina. In the Busulfan-treated rats, the tubules continue having, up to post-natal day 30, only Sertoli cells and scanty spermatogonia. In these, lanthanum penetration goes as far as the apical Sertoli cell region; the inter-Sertoli junctions still show tortuous strands, and most are oriented perpendicular to the basal lamina. This indicates that formation of the first competent inter-Sertoli junctions is temporo-spatially simultaneous with the appearance of zygotene-pachytene spermatocytes.