MORPHOLOGICAL OBSERVATIONS ON THE SPERMATOZOA OF ECHINOTHURID SEA URCHINS*

The morphology of the spermatozoa of three species of echinothurid sea urchins, Asthenosoma ijimai, Araeosoma owstoni, Hapalosoma gemmiferum, was investigated by means of transmission and scanning electron microscopy. The spermatozoa of these three species of echinothurid sea urchins have similar fine structure, but they differ in several features from the more familiar regular sea urchins. 1) The external anatomy of the head region of the echinothurid spermatozoon is diagnostic in that it has a highly elongated head. 2) The spermatozoon of echinothurid sea urchins has a very long slender nucleus, protruding on its proximal end, so that the shape of the nucleus resembles a sperhead. 3) The acrosomal granule in the acrosomal vesicle of the echinothurid spermatozoon is not a mass of homogenous particulate material but an electron opaque rod condensed in the central part of the acrosomal vesicle. Scanning electron microscopic examination revealed that echinothurid spermatozoa form acrosomal processes similar to those of other regular sea urchins. 4) The basal body is situated just beneath the middle of the posterior protrusion of the nucleus. The distal centriole is located beside the basal body almost in contact with it. The axis of the distal centriole is almost but not quite parallel to that of the basal body. A satellite complex can be recognized around the posterior part of the proximal centriole.     

DUAL INNERVATION OF THE FOLIATE PAPILLAE OF THE RAT: AN ELECTROPHYSIOLOGICAL STUDY

The dual innervation of the foliate papillae of the rat by thechorda tympani and the glossopharyngeal nerves was determinedin this electrophysiological study. The magnitude of the chordatympani response to the chemical stimulation of the foliatepapillae was small and variable in different animals. Summatedresponses of both the chorda tympani and the glossopharyngealnerves to the stimulation of the foliate papillae showed similarpatterns such as long latencies, slowly rising responses afteronset of stimulation and slow declines by water ringing. Therelative responsiveness to 5 different chemicals applied tothe foliate papillae were almost the same for the chorda tympaniand the glossopharyngeal nerves. However, these 2 nerves produceddifferent patterns of response to various chemicals appliedto the fungiform, foliate and circumvallate papillae.     

Three Groups of Teratocarcinoma Antigens Co-Expressed in the Visceral Endoderm are Located in Mutually Exclusive Sites in the Adult Kidney

Monoclonal rat antibodies were prepared against glycoproteins isolated from murine teratocarcinoma OTT6050 by affinity chromatography on Ricinus communis agglutinin (RCA). These antibodies defined three distinct groups of antigens (OR antigens) commonly expressed in teratocarcinoma cells and in restricted sites of the kidney. OR 17 antigen was a new glycoprotein antigen and the biochemical properties were different from any membrane glycoprotiens or matrix glycoproteins so far described in teratocarcinoma cells. In the kidney, the antigen was found in the glomerular basement membrane, and to lesser extent in the endothelium of the glomerulus and blood vessels. On the other hand, OR 8 antigen corresponded to "brushin" defined by conventional antibodies, while OR 4 and 19 antigens were carbohydrate antigens resembling "TC antigen". OR 8 antigen was detected in the tubular brush border and the epithelium of Bowman's capsule. OR 4 antigen was present in the collecting tubules and the thin loop of Henle. Although OR 19 antigen showed distribution similar to OR 4 antigen, there were genetic differences in the expression of the former antigen. All of the antigens were present in early postimplantation embryos of the mouse, notably in the visceral endoderm. These antigens are interesting subjects to study the mechanism of differentiation-dependent control of gene expression, since antigenic distribution is specialized as the result of differentiation.     

INHIBITORY EFFECT OF RABBIT SERUM FACTOR ON IN VITRO OOCYTE MATURATION OF THE TELEOST FISH,ORYZIAS LATIPES*

The present study indicates that a factor in rabbit serum inhibits the in vitro steroid- and gonadotropin-induced maturation of oocytes of the teleost fish, Oryzias latipes. Such inhibitory activity could not be recognized in the serum of this fish or in the fluids from mammalian follicles. Passage of the serum inhibitor through a cellulose membrane indicated that it has a molecular weight of less than 3,500. The inhibitory activity on steroid-induced oocyte maturation was not destroyed by heating, by repeated freezing and thawing or by treatment with proteolytic enzymes, lipase or amylases. However, its activity could be removed by extraction with charcoal but not with ethyl ether or toluene. The inhibitory action of the heat-stable and dialyzable serum factor was reversible. The factor appears to exert its inhibitory effect upon the oocyte itself in an early step of maturation, rather than upon the follicle cells.     

In Vitro Orientation of Fibroblasts and Myoblasts on Aligned Collagen Film

A collagen film in which the collagen fibers were aligned was prepared and characterized by scanning electron microscopy. Cell orientation on this film was studied in vitro using human fibroblasts and chick embryo myoblasts. Ninety-four percent of innoculated fibroblasts were aligned along the direction of the collagen fiber. The cell orientation was disturbed when cytochalasin B or colchicine was added to the culture medium. The myoblasts showed a similar alignment along the direction of collagen fiber. The scanning electron microscopic observation revealed that none of the cytoplasmic extensions had consistent relationships to the direction of collagen fiber. Myoblast fusion was accelerated on the aligned membrane as compared to a randomly oriented film, suggesting some role of contact guidance in muscle cell differentiation.     

EFFECTS OF ELECTRICAL STIMULATION OF CHORDA TYMPANI ON GLOSSOPHARYNGEAL NERVE RESPONSE TO THE FOLIATE PAPILLAE STIMULATION

The foliate papillae of the rat are dually innervated by thechorda tympani and the glossopharyngeal nerves. The effectsof electrical stimulation of the distal end of the cut chordatympani on the spontaneous discharges and the gustatory responsesof the glossopharyngeal nerve fibers were examined in the ratwhile gustatory stimuli were applied to the foliate papillae.Activities of 5 out of 35 taste units in the glossopharyngealnerve were influenced by this procedure. Three units showedan inhibitory effect, 1 unit showed an excitatory effect and1 unit changed its firing pattern. These facts may be derivedfrom alterations of the blood circulation in the vicinity ofthe taste receptor cells innervated by the glossopharyngealnerve fibers.