The eggs of 30 female chinook salmon, Oncorhynchus tshawytscha (Walbaum), were collected at spawning. Some eggs from each fish were collected for bacteriologic study. Two salmon produced eggs judged to be of poor quality which were not used. The remaining 28 of the 30 groups of eggs were fertilized from a single sperm pool and the eggs incubated in separate groups. Mortality data on the developing salmon were recorded regularly through the twelfth week on feed. Unfertihzed eggs from each group were surface-disinfected with an iodine solution, then crushed and subjected to a culture procedure designed to permit growth of as many bacterial types as possible. Bacteria were cultured and identified, and a comparison made of the types of organisms present in eggs from groups which later incurred high or low mortalities. Bacteria were recovered from both groups of salmon eggs. Although no single organism could be identified as a cause of increased mortality, the more frequent occurrence in the eggs of the 'high mortality' group of species of Vibrio, Listeria, Corynebacterium and Staphylococcus suggests that these bacteria may play a role. It is suggested that the cause of so-called early Ufestage disease of salmon is muUifactorial.

Recent investigators suggest that dermatomes extend as consecutive bands from the dorsal median line and question the existence of dorsal axial lines. Our observations were made on serial sections of human embryos and fetuses prepared with neurofibrillar stains.Cervical nerves 1, 6, 7 and 8 failed to have cutaneous branches in most cases, the remainder usually had cutaneous branches.With a few exceptions in T 1, all thoracic dorsal rami had cutaneous branches. Usually T 1, 2 and 3 became cutaneous through medial branches, while T 9 through 12 did so through lateral branches. However T 4 through 8 constitute a transition zone where many of these nerves became cutaneous through both medial and lateral branches. Thoracic 4, 5 and 6 tended to have cutaneous distribution through medial branches, but T 7 and 8 through lateral branches.All lumbar dorsal rami having cutaneous distribution did so through lateral branches, but independent branches became progressively less frequent below L 1.Lumbar 4 lacked direct cutaneous branches in most cases and succeeding nerves in all cases. These nerves form the dorsal sacral plexus. The deficit in cutaneous distribution of lower lumbar rami was not as pronounced as in the lower cervical region. A deficit is significant in relation to dorsal axial lines.

No abstract

Embryos from superovulated female mice that developed in vitro from the two-cell stage were compared with in vivo embryos with respect to yield of blastocytes, number and types of cells, morphology in histologic section, and DNA polymerase activities. Significantly more embryos developed into blastocytes in vitro (93%) than in vivo (18%). Inner cell mass (ICM) cells comprised approximately 30% of total cells in late morula/early blastocyst stage embryos developed either in vitro or in vivo. However, the in vitro embryos developed approximately half the number of total cells as in vivo embryos, did not develop endoderm, and did not develop abembryonic trophoblast cells with morphologic characteristics of late preimplantation in vivo embryos. DNA-dependent DNA polymerase activities in in vitro embryos decreased in correspondence with the decrease in cell number resulting in per cell levels comparable to in vivo embryos. In contrast, the poly (A).oligo(dT)-dependent DNA polymerase activity was the same in embryos developing either in vitro or in vivo, indicating different regulatory mechanisms for the two enzyme activities. A variety of nutrients and growth factors in the culture medium did not increase cell numbers or DNA polymerase activities in embryos cultured for 3 days; extending the culture an additional 24 hours resulted in a loss of ICM cells and decreases in both DNA polymerase activities. These results show that the retarded growth of embryos in vitro is equally distributed between ICM and trophoblast, is not reversed by culture conditions that include serum growth factors, and is not due to decreased cellular levels of DNA polymerase activities.

Serial sections of human embryos and fetuses reveal that the sacral nerves which contribute fibers to the pelvic plexus often have dorsal, ventral, and oblique communicating rami. The ventral rami resemble the white rami of upper thoracic nerves and some of their fibers pass close by or through the chain ganglia and into the pelvic plexus. The sizes of the ventral rami are often in inverse proportion to that of the pelvic splanchnic nerves. That is, when the pelvic splanchnic nerves are poorly developed, the ventral rami are large, and conversely, when the pelvic splanchnic nerves are well developed, these rarni are small. The pelvic plexus was found to receive fibers from the sympathetic trunk and its ganglia in addition to those from the hypogastric plexus and the pelvic splanchnic nerves.Analysis of the observations made in this study together with a review of the literature in light of the present day classification of nerve fibers raises serious doubts concerning the limits set for the outflow of preganglionic nerve fibers from the spinal cord and the distribution of gray and white rami as described in recent textbooks in terms of their histological and physiological significance.Nerve fibers from the pelvic plexus can be traced along the walls of the bladder and the urachus and along the umbilical arteries into the umbilical cord. In embryos, only a few scattered nerve fibers were found distal to the umbilicus, but in fetuses at term, distinct nerve bundles were identified in the cord. These bundles sent branches to the walls of the umbilical arteries; other branches terminated as "end-nets'' in Wharton's jelly. These nets appeared as fine fibers with nodular swellings at irregular intervals. Innervation of the umbilical arteries was richest within the first few inches of the cord. Beyond this region, the nerves rapidly decreased in number. "End-nets'' were present as far as four inches from the umbilicus. Granular cells resembling Langerhans' cells were found in the cord. Often these cells were closely associated with fine nerve fibers.This study is concerned mainly with the nerve contributions to the pelvic (inferior hypogastric) plexuses. Observations are included on the contributions from the pelvic plexus to the umbilical cord. The general pattern of the nerve pathways of sympathetic fibers through the lumbar splanchnic nerves and the hypogastric plexus and nerves and that of parasympathetic fibers by way of the pelvic splanchnic nerves to the pelvic plexuses are well recognized. However, certain aspects of these pathways are not so well understood.The pelvic plexuses lie in close relation to the lateral surfaces of the pelvic viscera. Each plexus may be divided into regional parts which are named according to the organs to which they are anatomically and physiologically related. Both sympathetic and parasympathetic ganglion cells are found in these plexuses. The AM. J. ANAT., 128: 485-498. parasympathetic cells are thought to have migrated from the sacral segments of the central nervous system...

This is one of a series of papers on the structure and development of the cranial and spinal nerves. These observations were made on serial sections of human embryos and fetuses cut in different planes and stained with various neurological methods. These include the protargol method of Bodian ('36) and the silver gelatin method of Pearson and O'Neill ('46 In accordance with the Nomina Anatomica as revised by the Seventh International Congress of Anatomists of 1963, the terms nervus accessorius (accessory nerve) and musculus sternocleidomastoideus ( sternocleidomastoid muscle) will be used. OBSERVATIONSThis study is primarily concerned with the course of the accessory nerve and its relation to the upper cervical nerves. Since the hypoglossal nerve in mammals represents phylogenetically a fusion of several of the most rostra1 spinal nerves in lower forms, a consideration of this nerve will also be included.A small, spindle shaped ganglion ( fig. 1 ) was found in relation to the hypoglossal nerve on each side of a 47 mm human fetus (no. 101). The peripheral root of each ganglion joined the caudal roots of the hypoglossal nerve on each side and the conjoined bundles passed through the hypoglossal canal. This ganglion lies ventral to the trunk of the spinal accessory nerve and is located just dorsal to the hypoglossal canal. It more closely resembles a dorsal root ganglion of a typical spinal nerve than it does the accessory ganglia along the trunk of the accessory nerve. This is the only human embryo in our collection and in those which we studied at the Carnegie Institution which possessed a ganglion of this type connected to the hypoglossal nerve.The first cervical nerves were studied on both sides in 25 human embryos and fetuses making a total of 50 first cervical nerves. The presence or absence of dorsal root ganglia were noted. When a ganglion was present it was recorded as being small, medium sized or large. These ganglia ranged in size from a small cluster of cells to a mass approximating the size of the dorsal root ganglia of the second cervical nerve. The former were classified as small while the latter were considered to be large. When the ganglia appeared to be about one-half to one-third of the size of the second cervical dorsal root ganglia they were classified as medium sized. Clusters of ganglion cells on some first cervical nerves were often so small that in the gross adult specimen they would probably not be seen without a microscopic examination. The ganglion cells frequently occurred in more than one group or cluster along the course of a dorsal root ( fig. 2 ) . Those located within the spinal dura mater or the

The development of the structural pattern of the lower sacral and coccygeal segments of the spinal cord in human, rabbit and monkey embryos and fetuses has been studied. The changes observed in serial sections from above downward are outlined, beginning with typical sections through the lower sacral cord. Among the changes, other than diminution in size of the spinal cord and reduction in size of the lower spinal nerves, there i s a gradual disappearance of the posterior funiculus. As this occurs the gray matter appears to spread dorsally and the central canal widens. The gray matter becomes reduced in size and the lateral funiculus extends farther dorsally. A little lower down, the gray matter of the alar plate is reduced further in size and there is corresponding enlargement of the central canal. This enlargement constitutes the terminal ventricle. The spinal cord rapidly becomes smaller as both the fibers and the gray matter are diminished. In some specimens, fibers decussate dorsal to the lower end of the terminal ventricle. Little remains of the lower end of the spinal cord except the ependymal wall of the central canal and the surrounding fiber bundles. The shape and size of the lower end of the central canal is subject to variations.In the lower part of the spinal cord a longitudinal bundle on each side is formed by fiber contributions from the anterior horn cells in the basal plates. This bundle contributes fibers to the fifth sacral and the first and second coccygeal nerves. It is designated the sacrococcygeal fasciculus.The general structural plan and development of the human spinal cord are described i n current textbooks of anatomy and embryology (Goss, '59; Romanes, '64; Arey, '65; Hamilton et al., '62; Patten, '46; Streeter, '12). However, certain aspects of the development and structure of the lower end of the spinal cord have not been adequately investigated or described. This paper is concerned mainly with the structural pattern of this region and the changes that take place in this pattern during the first few months of human development. MATERIALS AND METHODSThis study i s based on the serial sections of human embryos and fetuses which were stained with neurological methods. They include the protargol method of Bodian ( ' 3 6 ) , the silver gelatin method of Pearson and Whitlock ('49) and other methods developed in this laboratory by the authors. The material used in this study includes human specimens whose crown-rump lengths (CRL) range from 8 m m to 130 mm. Also included for study are rabbit and monkey embryos which had been sectioned serially and stained with silver methods. OBSERVATIONSThe caudal end of the spinal cord in the human embryo and fetus tapers into a cone-shaped structure which constitutes in the adult the conus medullaris and the filum terminale. The spinal nerves in lumbar and upper sacral levels are large compared with the lower sacral and coccygeal spinal nerves which become progressively smaller from above downward. The dorsal roots of these nerves diminish more ...

In human embryos and fetuses, a small bundle of nerve fibers from the anterior and posterior vagal trunks descends between the layers of the hepatogastric ligament. These fibers pass to the region of the junction of the umbilical vein with the ductus venosus. At this junction, there is a slight thickening of the muscular wall. Nerve fibers pass to this junction and the proximal portion of the umbilical vein.Fibers from the posterior vagal trunk follow the left gastric artery to the celiac plexus. Fibers from this plexus follow the hepatic artery into the lesser omentum and along the portal vein to the liver. Continuing along the left branch of the portal vein, fibers reach the proximal portion of the umbilical vein and its junction with the ductus venosus.Ganglion cells were observed along the course of vagus nerve fibers to the umbilical vein. In embryos these cells were observed on the lower end of the anterior vagal trunk near the attachment of the upper end of the lesser omentum to the lower end of the esophagus. In older fetuses they were found in a small ganglion in the connective tissue sunounding the distal end of the ductus venosus.This study is based on human embryos and fetuses which were sectioned serially and prepared with neurological stains. These include the protargol method of Bodian ('36), the silver method of Pearson and Whitlock ('49) and other staining procedures recently developed in this laboratory by Sauter.When blood returns from the placenta to the fetus through the umbilical vein, it passes through the abdominal wall and into the intra-abdominal portion of the umbilical vein. This vein joins the left branch of the portal vein where the latter crosses the left longitudinal fissure which separates the right and left lobes of the liver. From here returning blood may flow through either of two paths. One path leads through the sinusoids of the liver and the hepatic veins to reach the inferior vena cava. The other path leads through the ductus venosus and into the inferior vena cava.The proximal end of the umbilical vein is in close relation to the liver and is partly surrounded by it. Its walls contain some smooth muscle. The volume and rate of blood flow through the ductus venosus is thought to be partly governed by the size of the umbilical vein. When the smooth muscle fibers in the wall of the umbilical vein contract, the lumen of this vessel is diminished and the flow of blood is reduced. In fetal sheep a band of smooth muscle in AM. J. ANAT.. 125 345-352.