Sertoli cell development of pig testis in the fetal and neonatal period

The Sertoli cells of pig fetuses from 35 days postcoitum until 1 mo after birth have been investigated by light and electron microscopy in decapitated animals and their control littermates, as well as in untreated animals. Until 52 days postcoitum, Sertoli cells change in form during the formation of sex cords but from then onwards they are rather uniform. They primarily display an elongated nonindented nucleus with one or more prominent nucleoli, a well-developed Golgi apparatus, and in the basal compartment below or beside the nucleus, a large lipid droplet. There are large quantities of rough endoplasmic reticulum (RER) from 52 days postcoitum onwards, often with complex whirl forms and a parallel arrangement of profiles with relatively few ribosomes. After birth their numbers seem to be somewhat less, and by 1 mo after birth the RER profiles are often shorter and almost free of ribosomes. Clustered ribosomes are found in large quantities throughout the period under investigation. Especially in the early fetal period, the endoplasmic reticulum (ER) profiles show prominently filled cisternae. Mitochondria are mostly long and slender, or small and ovoid. Most have lamellar cristae, but mixed lamellar-tubular cristae can also be seen. Between decapitated, control and untreated animals no obvious ultrastructural differences could be observed. The peritubular cell sheath surrounding the sex cords did not show signs of differentiation into a layer of myoid cells.     

The cell structure of the subcutis of the guinea pig

The cytological status of subcutis of five normal male guinea pigs was studied qualitatively and quantitatively on the basis of membranous preparations stained by the method of Jasswoin (1932). The major part of the cells are fibroblasts (70,27 +/- 0,58%). 88,17 +/- 3,02% of this cell type are monoplasmatic fibroblasts. The second frequent cell type are histiocytes (27,84 +/- 0,78%). Mastcells are present only on the neighbourship of vessels. Leucocytes are found in 1,89 +/- 0,57%.     

The permeability of the guinea pig cochlear capillaries to horseradish peroxidase

Summary Guinea pigs were given horseradish peroxidase intracardially. Examination of the cochlear capillaries 2 to 10 min after the injection revealed that the capillaries of the vascular stria are permeable to the peroxidase whereas the capillaries of the basilar membrane, the spiral ligament, and the spiral prominence are impermeable.

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Zusammenfassung Meerrettich-Peroxydase wurde Meerschweinchen intracardial verabfolgt. Die Untersuchung der Kapillaren der Schnecke 2–10 min nach der Injektion zeigte, daß die Kapillaren der Stria vascularis für die Peroxydase permeabel waren, jene der Membrana basilaris, des Ligamentum spirale und der Prominentia spiralis dagegen impermeabel sind.

     

The lymphatic capillaries of the middle ear mucosa in the guinea pig ultrastructure and permeability

Summary The middle ear mucosa has an extensive lymphatic capillary network. Horseradish peroxidase passes through the lymphatic intercellular clefts and is taken up into intracellular vesicles.     

The central effect of noradrenaline on thermoregulation in the neonatal guinea pig.

Noradrenaline (10 microgram) injected into the lateral cerebral ventricle of guinea pigs aged 2 to 12 days produced a rapid increase in oxygen consumption and in colonic temperature at an ambient temperature of 30 degrees C. The increase was most pronounced in the youngest animals and decreased with advancing age, but was still significant at 12 days of age. Species differences and the role of ambient temperature in the responses are discussed.     

A peculiar arteriovenous leptomeningeal complex in the guinea pig

In most areas of the body, arteries and veins run close together, often sharing a common connective tissue sheath. One exception to this is observed in the brain, where arteries come in from the base and veins collect over the convexity. Classically the larger blood vessels are formed by three coats: intima, media, and adventitia. Leptomeningeal vessels are further reinforced by a monolayer of pial cells. In the guinea pig, however, above the corpus callosum we found a group of blood vessels (an artery and several veins) enclosed in a common leptomeningeal sheath. The artery arises at the confluence of the anterior cerebral arteries; the veins drain into the straight sinus. The epithelial nature of the sheath is evident by the close apposition of cell membranes, the presence of junctional devices, and the existence of a basal lamina. The ultrastructural features of this epithelium are similar to those of the arachnoid-dural membrane. Whether this peculiar vascular complex has any specific function needs to be investigated further. The presence of these vessels apparently 'isolated' within a leptomeningeal subcompartment may provide a suitable model to study vascular-extravascular-cerebrospinal fluid substance exchange.