Localization of glyoxylic acid-induced histofluorescence in surgically isolated medial basal hypothalamus of the rat

Summary Examination of glyoxylic acid-induced catecholamine histofluorescence in the hypothalamic median eminence of adult male rats revealed a linear pattern of fine varicosities coursing through the ependymal and fibrous zones, suggestive of juxtaposition to tanycytes. In order to determine the origin of these terminals, adult rats were subjected to complete isolation of the medial basal hypothalamus, using a small Halasz-Pupp knife. As rapidly as 24h after this deafferentation degenerative axon profiles were observed dorsal, as well as anterior and lateral, to the knife track. Occasionally at three days postoperatively, and routinely by seven days after surgery, fine-sized new fibres were seen passing through the knife wound. The linear profiles of varicosities observed in the normal median eminence remained traceable in the experimental preparations; the site of origin for these terminals therefore appears to be neurons of the arcuate (A12) and rostral periventricular (A14) regions. The results also indicate that fibres innervating the isolated area are capable of morphologically demonstrable new growth. The observations bear functional implications in assessing endocrine regulation following MBH isolation of the type used in this study.This study was supported by USPHS Postdoctoral Fellowship 5-F₂2-HD00630 (CT) and USPHS Grant NS-11642 (JRS). The authors wish to express their appreciation to Yvonne Cheung and Patricia Walker for technical assistance     

The goblet cavity matrix in the larval midgut of Hyalophora cecropia

The larval midgut of the silkmoth Hyalophora cecropia was examined using scanning electron microscopy. Goblet cells were observed to contain within their cavities a matrix plug. This matrix material was extruded onto the lumen side of the epithelium when the tissue was stretched. The rôle of this matrix material in maintenance of the capacity of the midgut to transport ions in vivo and in vitro is discussed.     

Fate of spermatozoa that do not participate in fertilization in the domestic fowl

Summary The fate of spermatozoa that do not participate in fertilization was investigated by electron microscopy. After artificial insemination, we observed several spermatozoa between the fibers of the outer layer of the vitelline membrane of the ovum. One or more spermatozoa were also found in a phagocytic vesicle of macrophages located in the intercellular space of the mucosal epithelium of the infundibulum or in the outer layer of the vitelline membrane.From these observations, we assume that the superfluous spermatozoa in the lumen of the anterior part of the oviduct might be removed by inclusion into the outer layer of the vitelline membrane and by phagocytosis by macrophages.The authors are greatly indebted to Assoc. Prof. Osamu Koga for his invaluable advice. The authors also wish to thank Mr. Takayuki Mri for his helpful suggestions and technical advice. This investigation was supported by a grant from the Ministry of Education of Japan (156185)     

Scanning electron microscopic study of spermatozoa from gossypol-treated rats

Summary Spermatozoa from the cauda epididymidis of gossypol-treated rats exhibit distinctive departures from the morphology of spermatozoa from control rats: wrinkled and disorganized cell membrane in the head and tail regions, cell membrane missing from segments of the tail midpiece and principal piece regions, malformed heads, decapitate spermatozoa, retention of a cytoplasmic droplet at variable loci along tail midpieces, and looped tails. The observations suggest that gossypol exerts its contraceptive effect during spermatocytogenesis and spermiogenesis, including the posttesticular development and maturation of spermatozoa in the epididymis.     

The structure and distribution of satellite cells of cardiac muscles in decapod crustaceans

Summary The structure and distribution of satellite cells of cardiac muscles were examined in twenty-one species of animals chosen from each tribe within the order Decapoda (Arthropoda, Crustacea). The satellite cells were found in all animals observed. Most of them are morphologically identical with those described in different striated muscles of other species, but some cells have unusual features. The decapod satellite cell occasionally lies right over the region corresponding to the intercalated disc between the apposed cardiac muscle cells. The cell sends cytoplasmic processes into the adjacent muscle cells, enabling the plasma membrane to make close contact with the cleft opening of the intercalated disc, and with the myofibril at the level of the Z-line. Another characteristic feature is the presence of paired cells. Such cells are clearly separated from each other over most of the contact area by the respective plasma membranes, which are smooth in appearance and devoid of specialized regions. The significance of the presence of satellite cells in decapod cardiac muscle and its possible role are discussed and compared with those described for other species.     

Fluorescence Transients as Indicator for the Existence of Regulatory Mechanisms in Photosynthetic Electron Transport

In green algae several characteristic differences in the slope of the fast 685 nm fluorescence transient indicate the existence of different mechanisms for the regulation of the photosynthetic electron transport in vivo with respect to the requirements for ATP and NADPH. Autotrophically cultivated Chlamydobotrys stellata exhibits a normal time curve of the fluorescence yield. Anaerobiosis and C0₂-deficiency raise the O-, I- and S-level, whereas the P- level is lowered and the I-D-decay disappears. The readdition of oxygen increases the fluorescence significantly. Supplementation of aerobic cells with CO₂ restores the normal fluorescence transients. The replacement of carbon dioxide by acetate as a carbon source in the light lowers the overall fluorescence emission and abolishes the D-P-increase and the P-S-decline. The presence of DCMU increases fluorescence only at high intensities of incedent light. Anaerobiosis in these photoheterotrophic algae lowers the fluorescence emission. In this case DCMU increases fluorescence even at low light intensities. In Gonium multicoccum, which shows a normal fluorescence transient when cultivated autotrophically, CO₂-deficiency abolishes the O-level and increases the I- and S-niveau. Additional anaerobiosis in CO₂-deficient cells raises the steady state emission. Readdition of oxygen to these cells raises the I- and S-level even more and prevents the build up of the P-level. In Gonium     

Possible sites of ultrafiltration in Tubifex tubifex Müller (Annelida,Oligochaeta)

Summary The endothelia of Tubifex tubifex Müller consist of myoendothelial cells, chloragocytes, or podocytes. The latter seem to occur only as windows on the ventral vessel which has an endothelium of myoendothelial cells elsewhere. The podocytes are large cells, with several processes on the inner side which ramify into several pedicels. These are aligned upon the outside of the basement membrane which lines the inside of the endothelium. The gaps between adjacent pedicels are about 40 nm wide. In capillaries fenestrated endothelia occur with irregular spacings measuring up to 0.4–1 m. A diaphragm in podocytes or capillary fenestrations do not seem to exist. The basement membrane is the only continuous layer lining the blood vessels and capillaries of Tubifex with a rather uniform diameter in the range of 50 nm. It is the only permeability barrier between blood and coelomic fluid.